MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Vision Research' source. Wed, 08 Feb 2012 23:31:50 +0100 http://www.medworm.com/index.php?rid=5666061&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22306925%26dopt%3DAbstract We present a series of experiments that examined these effects in depth. Experiment 1 explored the time course of disengagement effects. Experiments 2 and 3 explored the generalizability of disengagement effects by testing whether they could be observed when participants searched for targets defined by form instead of color. Finally, Experiment 4 validated the disengagement paradigm as a measure of disengagement and ruled out alternative explanations for slowed saccadic reaction times. Results confirm and extend our understanding of the influence of features within the focus of attention on when and where attention will shift next. PMID: 22306925 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5666061 Sat, 28 Jan 2012 05:00:00 +0100 5666061 http://www.medworm.com/index.php?rid=5666064&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22306678%26dopt%3DAbstract Authors: Mayer KM, Vuong QC Abstract Objects consist of features such as shape, motion and color, all of which can be selectively used for different object processing tasks. The present study investigated whether task demands influenced how well participants attended to features of novel colored dynamic objects that were task-relevant while ignoring those that were task-irrelevant. To address this, we used tasks which had different perceptual, learning and memory demands. The unattended features were systematically changed to measure their effects on how well participants could process the attended feature. In Experiment 1, participants discriminated simultaneously presented objects on the basis their shape or motion. We found that changes to unattended motion and color did not aff... Vision Research journals http://www.medworm.com/rss/comments.php?id=5666064 Fri, 27 Jan 2012 05:00:00 +0100 5666064 http://www.medworm.com/index.php?rid=5666063&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22306679%26dopt%3DAbstract Authors: Chanceaux M, Vitu F, Bendahman L, Thorpe S, Grainger J Abstract A saccadic choice task (Kirchner & Thorpe, 2006) was used to measure word processing speed in peripheral vision. To do so, word targets were accompanied by distractor stimuli, which were random strings of consonants presented in the contralateral visual field. Participants were also tested with the animal stimuli of Kirchner and Thorpe's original study. The results obtained with the animal stimuli provide a straightforward replication of prior findings, with the estimated fastest saccade latencies to animal targets being 140ms. With the word targets, the fastest reliable saccades occurred with latencies of around 200ms. The results obtained with word targets provide a timing estimate for word processing in... Vision Research journals http://www.medworm.com/rss/comments.php?id=5666063 Fri, 27 Jan 2012 05:00:00 +0100 5666063 http://www.medworm.com/index.php?rid=5666062&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22306680%26dopt%3DAbstract Authors: Sun H, Cooper B, Lee BB Abstract Vernier thresholds are known to be elevated when a target pair has opposite contrast polarity. Polarity reversal is used to assess the role of luminance and chromatic pathways in hyperacuity performance. Psychophysical hyperacuity thresholds were measured for pairs of gratings of various combinations of luminance (Lum) and chromatic (Chr) contrast polarities, at different ratios of luminance to chromatic contrast. With two red-green gratings of matched luminance and chromatic polarity (+Lum+Chr), there was an elevation of threshold at isoluminance. When both luminance and chromatic polarity were mismatched (-Lum-Chr), thresholds were substantially elevated under all conditions. With the same luminance contrast polarity and opposite chromati... Vision Research journals http://www.medworm.com/rss/comments.php?id=5666062 Fri, 27 Jan 2012 05:00:00 +0100 5666062 http://www.medworm.com/index.php?rid=5666066&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22289646%26dopt%3DAbstract Authors: Banai K, Amitay S Abstract Stimulus uncertainty produced by variations in a target stimulus to be detected or discriminated, impedes perceptual learning under some, but not all experimental conditions. To account for those discrepancies, it has been proposed that uncertainty is detrimental to learning when the interleaved stimuli or tasks are similar to each other but not when they are sufficiently distinct, or when it obstructs the downstream search required to gain access to fine-grained sensory information, as suggested by the Reverse Hierarchy Theory (RHT). The focus of the current review is on the effects of uncertainty on the perceptual learning of speech and non-speech auditory signals. Taken together, the findings from the auditory modality suggest that in addition... Vision Research journals http://www.medworm.com/rss/comments.php?id=5666066 Wed, 25 Jan 2012 05:00:00 +0100 5666066 http://www.medworm.com/index.php?rid=5666065&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22289647%26dopt%3DAbstract Authors: Aberg KC, Herzog MH Abstract Perceptual learning is an implicit form of learning which induces long-lasting perceptual enhancements. Perceptual learning shows intriguing characteristics. For example, a minimal number of trials per session is needed for learning and the interleaved presentation of more than one stimulus type can hinder learning. Here, we show that these and other characteristics of perceptual learning are very similar to characteristics of long-term potentiation (LTP), the basic mechanism of memory formation. We outline these characteristics and discuss results of electrophysiological experiments which indirectly link LTP and perceptual learning. PMID: 22289647 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5666065 Wed, 25 Jan 2012 05:00:00 +0100 5666065 http://www.medworm.com/index.php?rid=5666067&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22289645%26dopt%3DAbstract Authors: Baker DH, Wallis SA, Georgeson MA, Meese TS Abstract We studied the rules by which visual responses to luminous targets are combined across the two eyes. Previous work has found very different forms of binocular combination for targets defined by increments and by decrements of luminance, with decrement data implying a severe nonlinearity before binocular combination. We ask whether this difference is due to the luminance of the target, the luminance of the background, or the sign of the luminance excursion. We estimated the pre-binocular nonlinearity (power exponent) by fitting a computational model to ocular equibrightness matches. The severity of the nonlinearity had a monotonic dependence on the signed difference between target and background luminance. For dual target... Vision Research journals http://www.medworm.com/rss/comments.php?id=5666067 Tue, 24 Jan 2012 05:00:00 +0100 5666067 http://www.medworm.com/index.php?rid=5629838&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22273999%26dopt%3DAbstract Authors: Bulthé J, Op de Beeck H Abstract The McCollough effect is a contingent color after effect induced by adapting to colored gratings for several minutes. It has been demonstrated that a long-lasting adaptation effect such as the McCollough effect can be diminished by exposure to achromatic versions of the induction stimuli. However, the orientation specificity of this effect of post-adaptation exposure is not known. Here we report the findings from two experiments conducted to determine the influence of achromatic gratings and their orientation on the strength of the McCollough effect. After adaptation to the McCollough stimuli, participants were exposed to achromatic gratings or to one of two control conditions (either waiting in the dark or different-orientation achromatic... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629838 Fri, 20 Jan 2012 05:00:00 +0100 5629838 http://www.medworm.com/index.php?rid=5629839&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22273998%26dopt%3DAbstract Authors: Xu JP, He ZJ, Ooi TL Abstract We previously designed a push-pull perceptual training protocol that effectively reduces sensory eye dominance (SED) and enhances binocular depth detection in human adults (Xu, He, & Ooi, 2010a). During the training, an attention cue precedes a pair of binocular competitive stimulus to induce dominance of the weak eye and suppression of the strong eye. To verify that the success of the protocol is due to the suppression of the signals evoked by the stimulus in the strong eye, rather than to the attention cueing per se, we employed two new push-pull training protocols that did not involve attention cueing. Instead, we used the specific configurations of the boundary contours of the binocular competitive stimulus to render the strong eye sup... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629839 Wed, 18 Jan 2012 05:00:00 +0100 5629839 http://www.medworm.com/index.php?rid=5629840&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22269189%26dopt%3DAbstract Authors: Choi H, Watanabe T Abstract Although feedback is considered to be an important factor in perceptual learning (PL), its role is normally considered limited to facilitation, rather than direct inducement, of PL. Recent studies, however, have suggested feedback to be more actively involved in the inducement of PL. The current study demonstrates an even more significant role for feedback in PL: feedback can evoke PL of a feature without any bottom-up processing of that feature. We use a "fake feedback" method, in which the feedback is related to an arbitrarily chosen feature, rather than actual performance. We find evidence of PL with this fake feedback method both when the learned feature is absent from the visual stimulus (Experiment 1) and when it conflicts with the visual ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629840 Mon, 16 Jan 2012 05:00:00 +0100 5629840 http://www.medworm.com/index.php?rid=5629843&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22260785%26dopt%3DAbstract Authors: Feng G Abstract In the saccadic literature, the voluntary control of eye movement involves inhibiting automatic saccadic plans. In contrast, the dominant view in reading is that linguistic processes trigger saccade planning. The present study explores the possibility of a common control mechanism, in which cognitively driven responses compete to inhibit automatic, perceptually driven saccade plans. A probabilistic model is developed to account for empirical distributions of saccadic response time in anti-saccade tasks (Studies 1 and 2) and fixation duration in reading and reading-like tasks (Studies 3 and 4). In all cases the distributions can be decomposed into a perceptually based component and a component sensitive to cognitive demands. Parametric similarities among the... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629843 Fri, 13 Jan 2012 05:00:00 +0100 5629843 http://www.medworm.com/index.php?rid=5629842&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22266193%26dopt%3DAbstract Authors: Hussain Z, Bennett PJ, Sekuler AB Abstract Perceptual learning of 10-AFC texture identification is stimulus specific: after practice, identification accuracy drops substantially when textures are rotated 180°, reversed in contrast polarity, or when a novel set of textures is presented. Here we asked if perceptual learning occurs without any repetition of items during training, and whether exposure to greater stimulus variation during training influences transfer of learning. We trained three groups of subjects in a 10-AFC texture identification task on 2days. The Standard group viewed a fixed set of 10 textures throughout training. The Variable group viewed 840 novel sets of textures. The Switch group viewed different fixed sets of 10 textures on Days 1 and 2. In all grou... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629842 Fri, 13 Jan 2012 05:00:00 +0100 5629842 http://www.medworm.com/index.php?rid=5629841&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22266194%26dopt%3DAbstract Authors: Khuu SK, Khambiye S Abstract The visual system is able to infer three-dimensional (3D) shape from the surface shading-gradient of objects. Using Global Dot Motion (GDM) stimuli, we investigated the influence of shape from shading on the perception of coherent local and global motion. In Experiment 1, we report that the visual system is unable to detect the local motion of dots that undergo a change in 3D shape (convex to concave shape) from frame to frame. For this condition, GDM detection thresholds were approximately four times higher than when dots do not change shape. However, when shaded dots were perceptually two-dimensional (as with bipartite and horizontally shaded dots) GDM the visual system was able to detect the global motion regardless of a change in shading di... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629841 Fri, 13 Jan 2012 05:00:00 +0100 5629841 http://www.medworm.com/index.php?rid=5629848&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245220%26dopt%3DAbstract We examined variation in the visual system both within and among seven species of darters, colorful freshwater fishes of the genus Etheostoma. Using microspectrophotometry, we found that darters possess rod photoreceptor cells, single cone photoreceptor cells containing middle wavelength sensitive (MWS) visual pigments, and twin photoreceptor cells containing (LWS) visual pigments. No variation in peak sensitivity was detected among species or individuals in the rod class. In the MWS class, significant variation was detected among species and a strong statistical trend suggests differences among individuals. By contrast, all differences in the LWS class could be attributed to variation among individuals. Patterns of variation detected among species, among individuals, and among cone classe... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629848 Sun, 08 Jan 2012 05:00:00 +0100 5629848 http://www.medworm.com/index.php?rid=5629847&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245708%26dopt%3DAbstract Authors: Chu CH, Deng L, Kee CS Abstract We determined effects of hemiretinal form deprivation (i.e., form-depriving half of the retina) on central refractive development and posterior eye shape in chicks. Seventy-seven White Leghorn chicks were randomly assigned to receive superior (SRD, "Superior Retinal Deprivation" or inferior visual field deprivation, same principle applies for the following abbreviations, n=17), inferior (IRD, n=14), temporal (TRD, n=23) or nasal hemiretinal (NRD, n=23) form deprivation monocularly from day 5 to day 26. Central refractive errors, expressed as interocular difference in spherical equivalent (M), J0 and J45 astigmatic components, were measured using Hartinger refractometer at the beginning and weekly after treatment for 3weeks. At the end of the... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629847 Thu, 05 Jan 2012 05:00:00 +0100 5629847 http://www.medworm.com/index.php?rid=5629846&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245709%26dopt%3DAbstract Authors: Breitmeyer BG, Jacob J Abstract Using metacontrast masking we examined the temporal dynamics of surface completion in object vision. By varying the stimulus onset asynchrony between the target object and the flanking mask(s), we obtained estimates of the time required for the entire surface contrast to fill out within the area delimited by the contours/edges of the target. The estimated speed of the filling-out process was 36.0deg/s. Using existing estimates of cortical magnification, the computed filling-out speed in terms of cortical distance is .385m/s, a value that approximates the estimated cortical filling-in speed and the speed of horizontal propagation in monkey V1. We discuss our results in relation to (1) prior findings of filling-in and filling-out phenomena, us... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629846 Thu, 05 Jan 2012 05:00:00 +0100 5629846 http://www.medworm.com/index.php?rid=5629845&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22245710%26dopt%3DAbstract Authors: Morgan MJ Abstract Prolonged inspection of moving stimuli causes stationary stimuli to appear moving in the opposite direction to the adapting stimulus (the Waterfall effect). It has been claimed that distracting the viewer's attention from the adapting stimulus by a secondary task reduces the strength of adaptation. However, the method used to show the effect of distraction (the duration of the aftereffect) is potentially susceptible to bias. The experiments reported here show no effect in genuinely naïve subjects, or in experienced observers using a variety of cancellation procedures to measure the effect. PMID: 22245710 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5629845 Thu, 05 Jan 2012 05:00:00 +0100 5629845 http://www.medworm.com/index.php?rid=5629844&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22248730%26dopt%3DAbstract Authors: Yue X, Biederman I, Mangini MC, Malsburg CV, Amir O Abstract Shape representation is accomplished by a series of cortical stages in which cells in the first stage (V1) have local receptive fields tuned to contrast at a particular scale and orientation, each well modeled as a Gabor filter. In succeeding stages, the representation becomes largely invariant to Gabor coding (Kobatake & Tanaka, 1994). Because of the non-Gabor tuning in these later stages, which must be engaged for a behavioral response (Tong, 2003; Tong et al., 1998), a V1-based measure of shape similarity based on Gabor filtering would not be expected to be highly correlated with human performance when discriminating complex shapes (faces and teeth-like blobs) that differ metrically on a two-choice, match-... Vision Research journals http://www.medworm.com/rss/comments.php?id=5629844 Thu, 05 Jan 2012 05:00:00 +0100 5629844 http://www.medworm.com/index.php?rid=5585575&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22230381%26dopt%3DAbstract Authors: Willmore BD, Bulstrode H, Tolhurst DJ Abstract Neuronal populations in the primary visual cortex (V1) of mammals exhibit contrast normalization. Neurons that respond strongly to simple visual stimuli - such as sinusoidal gratings - respond less well to the same stimuli when they are presented as part of a more complex stimulus which also excites other, neighboring neurons. This phenomenon is generally attributed to generalized patterns of inhibitory connections between nearby V1 neurons. The Bienenstock, Cooper and Munro (BCM) rule is a neural network learning rule that, when trained on natural images, produces model neurons which, individually, have many tuning properties in common with real V1 neurons. However, when viewed as a population, a BCM network is very different... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585575 Tue, 03 Jan 2012 05:00:00 +0100 5585575 http://www.medworm.com/index.php?rid=5585574&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22239962%26dopt%3DAbstract Authors: Red SD, Patel SS, Sereno AB Abstract In a modified reflexive spatial attention paradigm, when the cue and the target are at the same spatial location, processing of the target is faster when the cue and the target have different shapes compared to same (shape effect). Recent physiological findings suggest distinct population level encoding of shape in ventral versus dorsal cortical visual streams in monkeys. In human observers, we tested whether the effect of shape on reflexive spatial attention could be attributed to ventral and/or dorsal stream encoding of shape. In the modified reflexive spatial attention paradigm, we varied the shapes of the cue and target. Based on data from monkey physiology (Lehky & Sereno, 2007), we selected four pairs of cue and target shapes.... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585574 Tue, 03 Jan 2012 05:00:00 +0100 5585574 http://www.medworm.com/index.php?rid=5585577&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227607%26dopt%3DAbstract Authors: Alexander RG, Zelinsky GJ Abstract Do the target-distractor and distractor-distractor similarity relationships known to exist for simple stimuli extend to real-world objects, and are these effects expressed in search guidance or target verification? Parts of photorealistic distractors were replaced with target parts to create four levels of target-distractor similarity under heterogenous and homogenous conditions. We found that increasing target-distractor similarity and decreasing distractor-distractor similarity impaired search guidance and target verification, but that target-distractor similarity and heterogeneity/homogeneity interacted only in measures of guidance; distractor homogeneity lessens effects of target-distractor similarity by causing gaze to fixate the tar... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585577 Mon, 02 Jan 2012 05:00:00 +0100 5585577 http://www.medworm.com/index.php?rid=5585576&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227608%26dopt%3DAbstract Authors: Mould MS, Foster DH, Amano K, Oakley JP Abstract There is no standard method for classifying eye fixations. Thresholds for speed, acceleration, duration, and stability of point of gaze have each been employed to demarcate data, but they have no commonly accepted values. Here, some general distributional properties of eye movements were used to construct a simple method for classifying fixations, without parametric assumptions or expert judgment. The method was primarily speed-based, but the required optimum speed threshold was derived automatically from individual data for each observer and stimulus with the aid of Tibshirani, Walther, and Hastie (2001). An optimum duration threshold, also derived automatically from individual data, was used to eliminate the effects of ins... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585576 Mon, 02 Jan 2012 05:00:00 +0100 5585576 http://www.medworm.com/index.php?rid=5585579&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227158%26dopt%3DAbstract Authors: Festman Y, Braun J Abstract We studied the spreading of feature-based attention from attended to ignored motion fields (linear, circular, and combinations). When observers attended one of two superimposed motion fields on one side of the visual midline, sub-threshold priming by an ignored motion field was altered significantly on the opposite side of the midline. This attentional spreading was observed only when attended and ignored motion fields conformed to a complex global flow, not when they shared the same linear motion. These findings corroborate an earlier study (Festman & Braun, 2010), which obtained similar results with a complementary methodology. We conclude that feature-based attention is more complex than hitherto appreciated in that it spreads preferentia... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585579 Thu, 29 Dec 2011 05:00:00 +0100 5585579 http://www.medworm.com/index.php?rid=5585578&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22227159%26dopt%3DAbstract In this study, we investigated whether mixing easy and difficult trials can lead to learning in the difficult conditions. We hypothesized that while feedback is necessary for significant learning in training regimes consisting solely of low training accuracy trials, training mixtures with sufficient proportions of high accuracy training trials would lead to significant learning without feedback. Thirty-six subjects were divided into one experimental group in which trials with high training accuracy were mixed with those with low training accuracy and no feedback, and five control groups in which high and low accuracy training were mixed in the presence of feedback; high and high training accuracy were mixed or low and low training accuracy were mixed with and without feedback trials. Contr... Vision Research journals http://www.medworm.com/rss/comments.php?id=5585578 Thu, 29 Dec 2011 05:00:00 +0100 5585578 http://www.medworm.com/index.php?rid=5542372&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22186224%26dopt%3DAbstract This study tests the hypothesis that the recognition of a face is facilitated when the face has previously been presented in a rapid rather than a slow view sequence. We used a sequential comparison task, in which a first face, rotating back and forth around a left or a right three-quarter view, was followed, after a 1-s delay, by a static view of a second face, with the same or a different viewpoint. We compared rapid (180ms per view) and slow (720ms per view) sequences to evaluate the timing constraints of temporal view association, and video and view sequences to evaluate the importance of motion smoothness. Response times were faster for rapid view sequences, showing the importance of perceiving the views in a short temporal window. When the views of a face are perceived in a rapid seq... Vision Research journals http://www.medworm.com/rss/comments.php?id=5542372 Tue, 13 Dec 2011 05:00:00 +0100 5542372 http://www.medworm.com/index.php?rid=5542371&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22186225%26dopt%3DAbstract CONCLUSIONS: In the afoveate chick, RRG lenses have an effect on central refraction and eye growth only if the central plano zone is small (<4mm). For the second type of RRG lens with a central plano zone of about 2mm, inhibitory effects on eye growth were detected in both the center and periphery even though the optical power of the lenses in the periphery was low. PMID: 22186225 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5542371 Tue, 13 Dec 2011 05:00:00 +0100 5542371 http://www.medworm.com/index.php?rid=5542370&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22186226%26dopt%3DAbstract We describe a perceptual asymmetry found in stereoscopic perception of overlaid random-dot surfaces. Specifically, the minimum separation in depth needed to perceptually segregate two overlaid surfaces depended on the distribution of dots across the surfaces. With the total dot density fixed, significantly larger inter-plane disparities were required for perceptual segregation of the surfaces when the front surface had fewer dots than the back surface compared to when the back surface was the one with fewer dots. We propose that our results reflect an asymmetry in the signal strength of the front and back surfaces due to the assignment of the spaces between the dots to the back surface by disparity interpolation. This hypothesis was supported by the results of two experiments designed to r... Vision Research journals http://www.medworm.com/rss/comments.php?id=5542370 Tue, 13 Dec 2011 05:00:00 +0100 5542370 http://www.medworm.com/index.php?rid=5542369&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22186227%26dopt%3DAbstract Authors: Megna N, Rocchi F, Baldassi S Abstract Visual attention is captured by transient signals in the periphery of the visual field, allowing enhanced perceptual representations in spatial tasks. However, it has been reported that the same cues impair performance in temporal tasks (e.g. Yeshurun, 2004; Yeshurun & Levy, 2003). This findings suggest that transient attention enhances the activity of slow, high-resolution channels, like parvocellular neurons, and/or shuts off faster channels better sensitive to low spatial frequencies, such as the ones of the magnocellular system. To test this idea, we have measured the spatio-temporal perceptive fields for transiently cued signals at various eccentricities using the Classification Images (CIs) technique. At near eccentricities ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5542369 Tue, 13 Dec 2011 05:00:00 +0100 5542369 http://www.medworm.com/index.php?rid=5501909&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22142786%26dopt%3DAbstract Authors: Daar M, Wilson H Abstract There is strong evidence that higher visual areas in the brain encode face viewpoint. The current study aims to shed light on the nature of this representation. Using a psychophysical adaptation paradigm based on Fang and He (2005), we compared the effects of adapting to full faces, head outline only, and internal features only, while testing with full faces in each case (12 subjects). We found reliable viewpoint aftereffects in all three conditions. The combined magnitude of the aftereffects from the two partial conditions was less than the aftereffect from full faces, suggesting a nonlinear combination of internal features and head outline. In a second experiment, we found that changing the direction of eye gaze did not modulate the viewpoint af... Vision Research journals http://www.medworm.com/rss/comments.php?id=5501909 Mon, 28 Nov 2011 05:00:00 +0100 5501909 http://www.medworm.com/index.php?rid=5501918&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22138335%26dopt%3DAbstract We examined whether subset search takes place when participants have less specific foreknowledge of the target (when the target is one of two possible items), measuring eye movements as well as reaction times. When there were unequal ratios of distractors, fixations were initially directed to the small subset. These initial eye movements were often directed between items with the same feature, suggesting guidance from pooled feature values. There was stronger guidance within color- than orientation-defined groups, although the features were balanced for salience. The results suggest that grouping of items by color operates more globally than grouping in orientation. PMID: 22138335 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5501918 Fri, 25 Nov 2011 05:00:00 +0100 5501918 http://www.medworm.com/index.php?rid=5501916&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22138530%26dopt%3DAbstract Authors: Motoyoshi I, Matoba H Abstract In contrast to the classical findings of lightness constancy, recent psychophysical studies show the strong dependency of the perceived reflectance of a surface on the structure of the natural illumination. The present study examined this inconstancy for systematic variations in the light field and an image-based explanation for it. Observers matched the specular and diffuse reflectance of a three-dimensional object in a complex scene under a fixed light field to that in the scene under different light fields with variable mean, contrast, and gamma. For the both specular and diffuse components, the matched reflectance was relatively constant against changes in the mean illuminance but varied extensively with changes in the contrast and gamma ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5501916 Fri, 25 Nov 2011 05:00:00 +0100 5501916 http://www.medworm.com/index.php?rid=5501919&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22133595%26dopt%3DAbstract Authors: Kojima H, Kawabata Y Abstract Luminance and color information are considered to be processed in parallel systems. The integration of information from these two separate systems is crucial for the visual system to produce a coherent percept. To investigate how luminance and color lights are perceived in time, we measured the perceived duration of light stimuli with and without colors in a paradigm involving simultaneous perception with presentation of two successive stimulus frames. Luminance contrast and color contrast of the stimuli were set with a chromatic substitution technique. In Experiment 1, the perceived duration of both chromatic stimuli and achromatic stimuli increased as the luminance contrast decreased. Experiment 2 tested if the duration of the percept was in... Vision Research journals http://www.medworm.com/rss/comments.php?id=5501919 Tue, 22 Nov 2011 05:00:00 +0100 5501919 http://www.medworm.com/index.php?rid=5501917&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22138529%26dopt%3DAbstract CONCLUSION: Opposed retinal luminances or colors were averaged out by binocular fusion, but could be retrieved by a special afterimage technique in Experiment 6. Conversely, in Experiment 7 dichoptic target spots flickered in counterphase but background spots flickered in-phase to the two eyes. RESULT: The targets were invisible monocularly but became visible as reduced-flicker when fused binocularly. We conclude that two eyes were worse than one eye when opposite colors or movements were fused (Experiments 1-6) but were better than one when binocular correlations could be extracted (Experiment 7). These experiments show how much of the visual information gets transmitted, gets discarded, can still be retrieved, or reaches conscious awareness. PMID: 22138529 [PubMed - as supplied by pu... Vision Research journals http://www.medworm.com/rss/comments.php?id=5501917 Tue, 22 Nov 2011 05:00:00 +0100 5501917 http://www.medworm.com/index.php?rid=5501914&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22142785%26dopt%3DAbstract Authors: Bosten JM, Mollon JD Abstract Kirschmann's Fourth Law states that the magnitude of simultaneous color contrast increases with the saturation of the inducing surround, but that the rate of increase reduces as saturation increases. Others since Kirschmann have agreed and disagreed. Here we show that the form of the relationship between simultaneous color contrast and inducer saturation depends on the method of measurement. Functions were measured by four methods: (i) asymmetric matching with a black surround, (ii) asymmetric matching with a surround metameric to equal energy white, (iii) dichoptic matching, and (iv) nulling an induced sinusoidal modulation. Results from the asymmetric matching conditions agreed with Kirschmann, whereas results from nulling and from dichoptic... Vision Research journals http://www.medworm.com/rss/comments.php?id=5501914 Sat, 19 Nov 2011 05:00:00 +0100 5501914 http://www.medworm.com/index.php?rid=5466882&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119774%26dopt%3DAbstract Authors: Herzog MH, Aberg KC, Frémaux N, Gerstner W, Sprekeler H Abstract Perceptual learning improves perception through training. Perceptual learning improves with most stimulus types but fails when certain stimulus types are mixed during training (roving). This result is surprising because classical supervised and unsupervised neural network models can cope easily with roving conditions. What makes humans so inferior compared to these models? As experimental and conceptual work has shown, human perceptual learning is neither supervised nor unsupervised but reward-based learning. Reward-based learning suffers from the so-called unsupervised bias, i.e., to prevent synaptic "drift", the average reward has to be exactly estimated. However, this is impossible when two or more stimul... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466882 Sat, 19 Nov 2011 05:00:00 +0100 5466882 http://www.medworm.com/index.php?rid=5466883&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22119039%26dopt%3DAbstract Authors: Anderson AJ, Wassnig SE Abstract Spatial frequency discrimination could simply reflect the ability to discriminate local differences in width when sinusoidal gratings are used. We introduced random fluctuations in the half-cycle widths of both extended 1c/° gratings and those restricted to 1.5 cycles (i.e. two bars of identical phase), as we hypothesised that discrimination for large gratings would be more robust to this distortion in the presence of a genuine spatial frequency sensitive mechanism that averaged information across a wide area. To exclude the possibility of a local mechanism that averaged through scanning eye movements, experiments were repeated with a short presentation time. We also repeated the experiment with a fixation point and the central 4° of the ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466883 Fri, 18 Nov 2011 05:00:00 +0100 5466883 http://www.medworm.com/index.php?rid=5466886&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100817%26dopt%3DAbstract Authors: Betts LR, Sekuler AB, Bennett PJ Abstract Contrast-dependent interactions between classical (CRF) and non-classical regions (nCRF) of visual neuron receptive fields are well documented in primate visual cortex. Physiological models that describe CRF and nCRF interactions in single neurons have recently been applied to psychophysical measures of spatial summation and suppression in motion perception of young adults (Tadin & Lappin, 2005). We wished to determine whether such models could account for the reduction in spatial suppression that occurs in normal aging (Betts et al., 2005). We applied three models to duration thresholds obtained in a simple motion discrimination task using drifting Gabor stimuli that ranged in spatial frequency from 0.5 to 4c/deg. We found tha... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466886 Tue, 15 Nov 2011 05:00:00 +0100 5466886 http://www.medworm.com/index.php?rid=5466889&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100814%26dopt%3DAbstract Authors: Huang CB, Lu ZL, Dosher BA Abstract Perceptual learning, even when it exhibits significant specificity to basic stimulus features such as retinal location or spatial frequency, may cause discrimination performance to improve either through enhancement of early sensory representations or through selective re-weighting of connections from the sensory representations to specific responses, or both. For most experiments in the literature (Ahissar & Hochstein, 1996; Fahle & Morgan, 1996; Wilson, 1986), the two forms of plasticity make similar predictions (Dosher & Lu, 2009; Petrov, Dosher, & Lu, 2005). The strongest test of the two hypotheses must use training and transfer tasks that rely on the same sensory representation with different task-dependent decision ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466889 Sat, 12 Nov 2011 05:00:00 +0100 5466889 http://www.medworm.com/index.php?rid=5466888&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100815%26dopt%3DAbstract Authors: Philip K, Martinez A, Ho A, Conrad F, Ale J, Mitchell P, Sankaridurg P Abstract Total ocular higher order aberrations and corneal topography of myopic, emmetropic and hyperopic eyes of 675 adolescents (16.9±0.7years) were measured after cycloplegia using COAS aberrometer and Medmont videokeratoscope. Corneal higher order aberrations were computed from the corneal topography maps and lenticular (internal) higher order aberrations derived by subtraction of corneal aberrations from total ocular aberrations. Aberrations were measured for a pupil diameter of 5mm. Multivariate analysis of variance followed by multiple regression analysis found significant difference in the fourth order aberrations (SA RMS, primary spherical aberration coefficient) between the refractive error g... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466888 Sat, 12 Nov 2011 05:00:00 +0100 5466888 http://www.medworm.com/index.php?rid=5466887&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100816%26dopt%3DAbstract In conclusion, our results suggest that visual-field related parameters per se are inadequate in predicting successful collision avoidance. Individualized approaches which also consider compensatory strategies by means of eye and head movements should be introduced. PMID: 22100816 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5466887 Sat, 12 Nov 2011 05:00:00 +0100 5466887 http://www.medworm.com/index.php?rid=5466885&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100834%26dopt%3DAbstract Authors: Ho WC, Wong OY, Chan YC, Wong SW, Kee CS, Chan HH Abstract The purpose of this study was to investigate the effect of optical defocus on changes of electrical response as a function of retinal region. Twenty-three subjects (aged 19-25year) with normal ocular health were recruited for global flash multifocal electroretinogram (mfERG) recordings under control (fully corrected) condition, and short-term positive defocus (+2D and +4D) and negative defocus (-2D and -4D) conditions. The amplitudes and implicit times of direct (DC) and induced (IC) components of mfERG responses were pooled into six concentric rings for analyses. The mfERG responses demonstrated more significant changes in amplitude in paracentral retinal regions than in the central regions under defocused conditi... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466885 Sat, 12 Nov 2011 05:00:00 +0100 5466885 http://www.medworm.com/index.php?rid=5466884&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22100835%26dopt%3DAbstract Authors: Thie J, Sriram P, Klistorner A, Graham SL Abstract This paper describes a method to reliably estimate latency of multifocal visual evoked potential (mfVEP) and a classifier to automatically separate reliable mfVEP traces from noisy traces. We also investigated which mfVEP peaks have reproducible latency across recording sessions. The proposed method performs cross-correlation between mfVEP traces and second order Gaussian wavelet kernels and measures the timing of the resulting peaks. These peak times offset by the wavelet kernel's peak time represents the mfVEP latency. The classifier algorithm performs an exhaustive series of leave-one-out classifications to find the champion mfVEP features which are most frequently selected to infer reliable traces from noisy traces. Mo... Vision Research journals http://www.medworm.com/rss/comments.php?id=5466884 Sat, 12 Nov 2011 05:00:00 +0100 5466884 http://www.medworm.com/index.php?rid=5430368&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22086075%26dopt%3DAbstract Authors: Abrams J, Nizam A, Carrasco M Abstract Performance in visual tasks is limited by the low-level mechanisms that sample the visual field. It is well documented that contrast sensitivity and spatial resolution decrease as a function of eccentricity and that those factors impair performance in "higher level" tasks, such as visual search. Performance also varies consistently at isoeccentric locations in the visual field. Specifically, at a fixed eccentricity, performance is better along the horizontal meridian than the vertical meridian, and along the lower than the upper vertical meridian. Whether these asymmetries in visual performance fields are confined to the vertical meridian or extend across the whole upper versus lower visual hemifield has been a matter of debate. Here,... Vision Research journals http://www.medworm.com/rss/comments.php?id=5430368 Wed, 09 Nov 2011 05:00:00 +0100 5430368 http://www.medworm.com/index.php?rid=5430370&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079315%26dopt%3DAbstract Authors: Yu D, Akau MM, Chung ST Abstract Word reading speed in peripheral vision is slower when words are in close proximity of other words (Chung, 2004). This word crowding effect could arise as a consequence of interaction of low-level letter features between words, or the interaction between high-level holistic representations of words. We evaluated these two hypotheses by examining how word crowding changes for five configurations of flanking words: the control condition - flanking words were oriented upright; scrambled - letters in each flanking word were scrambled in order; horizontal-flip - each flanking word was the left-right mirror-image of the original; letter-flip - each letter of the flanking word was the left-right mirror-image of the original; and vertical-flip - ea... Vision Research journals http://www.medworm.com/rss/comments.php?id=5430370 Mon, 07 Nov 2011 05:00:00 +0100 5430370 http://www.medworm.com/index.php?rid=5430369&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079358%26dopt%3DAbstract Authors: Pritchard SJ, Hammett ST Abstract Perceived speed is modulated by a range of stimulus attributes such as contrast, luminance and adaptation duration. It has been suggested that such changes in perceived speed may influence driving behaviour. In order to evaluate the effect of luminance on driving speed we have measured subjects' driving speed in a driving simulator for a range of luminance and speed over time. The results indicate that reducing luminance results in a decrease in driving speed for all speeds measured. This reduction in driving speed at low luminance is consistent with previous findings that perceived speed increases at low luminance. However, the results also indicated that driving speed remained stable over a 30s period. The stability of driving speed over... Vision Research journals http://www.medworm.com/rss/comments.php?id=5430369 Thu, 03 Nov 2011 04:00:00 +0100 5430369 http://www.medworm.com/index.php?rid=5430371&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22067604%26dopt%3DAbstract Authors: Marlow P Abstract One function of the visual system is to combine the different views of the two eyes so that each object appears in a single direction. Using pairs of isolated dots, previous studies have found that binocular fusion gives way to diplopia if the disparity gradient between the dots is steep. This paper evaluates whether fusion is possible in the presence of steep disparity gradients if those gradients occur between the edges of two surfaces, not isolated dots. Two target squares with a steep disparity gradient were presented alone, or were incorporated into separate surfaces - one foreground, the other background. The addition of surfaces, or support texture, restored fusion, overcoming the disparity gradient constraint on fusion. Visual direction was the av... Vision Research journals http://www.medworm.com/rss/comments.php?id=5430371 Mon, 31 Oct 2011 04:00:00 +0100 5430371 http://www.medworm.com/index.php?rid=5385415&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22056519%26dopt%3DAbstract Authors: Calabro FJ, Beardsley SA, Vaina LM Abstract Estimation of time-to-arrival for moving objects is critical to obstacle interception and avoidance, as well as to timing actions such as reaching and grasping moving objects. The source of motion information that conveys arrival time varies with the trajectory of the object raising the question of whether multiple context-dependent mechanisms are involved in this computation. To address this question we conducted a series of psychophysical studies to measure observers' performance on time-to-arrival estimation when object trajectory was specified by angular motion ("gap closure" trajectories in the frontoparallel plane), looming (colliding trajectories, TTC) or both (passage courses, TTP). We measured performance of time-to-arri... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385415 Wed, 26 Oct 2011 04:00:00 +0100 5385415 http://www.medworm.com/index.php?rid=5385416&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22051893%26dopt%3DAbstract Authors: Bosworth RG, Petrich JA, Dobkins KR Abstract In order to investigate differences in the effects of spatial attention between the left visual field (LVF) and the right visual field (RVF), we employed a full/poor attention paradigm using stimuli presented in the LVF vs. RVF. In addition, to investigate differences in the effects of spatial attention between the dorsal and ventral processing streams, we obtained motion thresholds (motion coherence thresholds and fine direction discrimination thresholds) and orientation thresholds, respectively. The results of this study showed negligible effects of attention on the orientation task, in either the LVF or RVF. In contrast, for both motion tasks, there was a significant effect of attention in the LVF, but not in the RVF. These d... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385416 Sun, 23 Oct 2011 04:00:00 +0100 5385416 http://www.medworm.com/index.php?rid=5385420&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037361%26dopt%3DAbstract Authors: Griffiths H, Whittle J, Buckley D Abstract This paper reports two experiments to determine the contribution of the suppressing eye to the generation of saccadic eye movements in constant strabismus. Eye movements were recorded using a Skalar infra-red recorder. Experiment 1 tested six participants with constant strabismus, pathological suppression and no clinically demonstrable binocular single vision (BSV). We explored the effect of visual distractors presented monocularly (to either the fixing eye or the strabismic eye) and binocularly, on saccade latency and accuracy. Saccade latency significantly increased when distractors were presented to the strabismic eye compared to the no distractor condition. In all participants the effect on latency, with distractors presented ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385420 Fri, 21 Oct 2011 04:00:00 +0100 5385420 http://www.medworm.com/index.php?rid=5385418&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037363%26dopt%3DAbstract We examined the neural correlates of this deficit using functional MRI. Attentive tracking of 1, 2 or 4 moving targets was compared to passive viewing and to baseline fixation in an amblyopic group and an age-matched control group in six regions of interest: V1, middle temporal complex (MT+), superior parietal lobule (SPL), frontal eye fields (FEF), anterior intraparietal sulcus (IPS), and posterior IPS. Activation in all regions of interest, except V1, increased with attentional load in both groups. MT+ was less active in both eyes of the amblyopic group relative to controls for passive viewing and each of the tracking conditions. Anterior IPS and FEF were less active with amblyopic eye viewing when tracking four targets. These results implicate both the low-level passive and high-level a... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385418 Fri, 21 Oct 2011 04:00:00 +0100 5385418 http://www.medworm.com/index.php?rid=5385417&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22040596%26dopt%3DAbstract Authors: Seno T, Palmisano S, Ito H Abstract We added simulated vertical viewpoint jitter and oscillation to radial optic flow displays designed to induce forward vection. Display jitter and oscillation were both found to increase vection strength during, and reduce motion aftereffects (MAE) following, exposure to the optic flow (compared to no-jitter controls). Display jitter, which induced the strongest vection of all the conditions tested, was also found to increase the duration of vection aftereffects (VAE). PMID: 22040596 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5385417 Fri, 21 Oct 2011 04:00:00 +0100 5385417 http://www.medworm.com/index.php?rid=5385424&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037304%26dopt%3DAbstract Authors: Ivanov IV, Mullen KT Abstract Shape processing involves a progression from a local to global analysis. A key aspect of this is the binding of distributed local features into an overall form followed by the extraction of the shape independently of its local contrast and spatial scales, so enabling the shape to be encoded based on its proportions without reference to its exact size or retinal location. Here we use contour- and surface-defined radial frequency (RF) patterns in a shape discrimination task, previously thought to reflect a global processing stage that has reached contrast and scale invariance. We compare performance across different spatial scales for a wide range of RF patterns (contour spatial frequencies of 0.7-10.0cpd, pattern radii of 0.5-10.5°), and sharp... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385424 Thu, 20 Oct 2011 04:00:00 +0100 5385424 http://www.medworm.com/index.php?rid=5385423&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037305%26dopt%3DAbstract Authors: Gilliam JC, Wensel TG Abstract In order to identify candidate cation channels important for retinal physiology, 28 TRP channel genes were surveyed for expression in the mouse retina. Transcripts for all TRP channels were detected by RT-PCR and sequencing. Northern blotting revealed that mRNAs for 12 TRP channel genes are enriched in the retina. The strongest signals were observed for TRPC1, TRPC3, TRPM1, TRPM3, and TRPML1, and clear signals were obtained for TRPC4, TRPM7, TRPP2, TRPV2, and TRPV4. In situ hybridization and immunofluorescence revealed widespread expression throughout multiple retinal layers for TRPC1, TRPC3, TRPC4, TRPML1, PKD1, and TRPP2. Striking localization of enhanced mRNA expression was observed for TRPC1 in the photoreceptor inner segment layer, for T... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385423 Thu, 20 Oct 2011 04:00:00 +0100 5385423 http://www.medworm.com/index.php?rid=5385421&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037360%26dopt%3DAbstract Authors: Lev M, Polat U Abstract Collinear facilitation is a common phenomenon in the fovea, but it has been recently challenged at the human periphery. Since physiological studies show that facilitation is found at the periphery but only from outside the receptive field, our hypothesis was that facilitation at the periphery exists but from larger target-flanker separations than the fovea. Here, we applied a recent paradigm (Polat & Sagi, 2007) to probe facilitation at the periphery. We used a Yes/No detection task by measuring the false-positive reports (false-alarm, pfa) and hit-rate (phit) for a low-contrast Gabor target (between two flankers) that appeared randomly at the fovea or at the periphery (2° or 4°) to the right or left side. We used different target-flanker sepa... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385421 Thu, 20 Oct 2011 04:00:00 +0100 5385421 http://www.medworm.com/index.php?rid=5385419&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037362%26dopt%3DAbstract Authors: Kavšek M Abstract In a looking-time study, 24 infants 6months of age were presented with continuously folding and unfolding patterns of stripes. The luminances in the dynamic lightness constancy pattern were changed in such way that adults attribute them to changes of the various regions' orientation relative to the light source (lightness constancy display). The "reversed" lightness constancy stimulus consisted of a continuously folding and unfolding pattern, in which the luminance changes were not consistent with a striped surface illuminated from one side. The only difference between the animations was the relationship between the change in surface orientation and the change of luminances. The infants looked significantly longer at the reversed lightness constancy anim... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385419 Thu, 20 Oct 2011 04:00:00 +0100 5385419 http://www.medworm.com/index.php?rid=5385425&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037303%26dopt%3DAbstract Authors: Tapia E, Breitmeyer BG, Jacob J Abstract We examine metacontrast masking with texture-defined second-order stimuli. Our results reveal that (1) the monotonic type A as well as the nonmonotonic (U-shaped) type B metacontrast effect, which has been extensively examined with first-order luminance-defined stimuli, can be obtained with texture-defined second-order stimuli; and (2) while variations of luminance contrast are known to affect the magnitude of metacontrast with first-order stimuli, neither the size nor orientation contrast between texture elements defining the second-order stimuli have a significant impact on the magnitude or shape of metacontrast. These findings bear on theories of metacontrast masking by showing that the mechanism giving rise to nonmonotonic maski... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385425 Wed, 19 Oct 2011 04:00:00 +0100 5385425 http://www.medworm.com/index.php?rid=5385422&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22037306%26dopt%3DAbstract Authors: Sterkin A, Yehezkel O, Polat U Abstract Our recent neurophysiological findings provided evidence for collinear facilitation in detecting low-contrast Gabor patches (GPs) and for the abolishment of these collinear interactions by backward masking (BM) (Sterkin et al., 2008; Sterkin, Yehezkel, Bonneh, et al., 2009). We suggested that the suppression induced by the BM eliminates the collinear facilitation. Moreover, our recent study showed that training on a BM task overcomes the BM effect, hence, improves the processing speed (Polat, 2009). Here we applied training on detecting a target that is followed by BM in order to study whether reinforced facilitatory interactions can overcome the suppressive effects induced by BM. Event-Related Potentials (ERPs) were recorded before ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385422 Wed, 19 Oct 2011 04:00:00 +0100 5385422 http://www.medworm.com/index.php?rid=5385426&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22027344%26dopt%3DAbstract Authors: Guzzon D, Casco C Abstract The effect of visual experience is usually investigated through active (task dependent) training in a discrimination task. In contrast, the current work explored the psychophysical and electrophysiological correlates of passive (task independent) visual experience in texture segmentation by using an inattentional blindness-like paradigm (Mack et al., 1992). The psychophysical and electrophysiological responses to a segmented line-texture bar, with texture elements oriented either congruently (parallel) or noncongruently (orthogonal) to bar orientation, were collected after both short and long passive experience, with the texture presented on the background while subjects performed a primary task. Subjects were not able to distinguish the orientat... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385426 Mon, 17 Oct 2011 04:00:00 +0100 5385426 http://www.medworm.com/index.php?rid=5385427&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22024049%26dopt%3DAbstract Authors: Porter KB, Caplovitz GP, Kohler PJ, Ackerman CM, Tse PU Abstract Do the mechanisms that underlie the perception of translational and rotational object motion show evidence of independent processing? By probing the perceived speed of translating and/or rotating objects, we find that an object's form contributes in independent ways to the processing of translational and rotational motion: In the context of translational motion, it has been shown that the more elongated an object is along its direction of motion, the faster it is perceived to translate; in the context of rotational motion, it has been shown that the sharper the maxima of curvature along an object's contour, the faster it appears to rotate. Here we demonstrate that such rotational form-motion interactions are ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385427 Sat, 15 Oct 2011 04:00:00 +0100 5385427 http://www.medworm.com/index.php?rid=5385428&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22019797%26dopt%3DAbstract Authors: Benard Y, Lopez-Gil N, Legras R Abstract We optimize the subjective depth of focus (DoF) with combinations of spherical aberration (SA4) and secondary spherical aberration (SA6) in various levels. Subjective DoF was defined as the visual interval for which three 20/50 high-contrast letters was perceived acceptable (objectionable blur limits). We used an adaptive optics system to dynamically correct the observer's aberrations and control their accommodation. DoF was measured with a 0.18-D step on three non-presbyopic subjects. The target seen by the subjects was modified to include 25 combinations of SA4 and SA6 (i.e. 0, ±0.15 and ±0.30μm) for 3, 4.5 and 6mm of pupil diameter. We found a mean DoF of 1.97D with a 3mm pupil size, which decreased by 28% with a 4.5mm pupil a... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385428 Fri, 14 Oct 2011 04:00:00 +0100 5385428 http://www.medworm.com/index.php?rid=5385431&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22005388%26dopt%3DAbstract Authors: Bowns L Abstract Standard biologically inspired spatio-temporal energy models of how humans perceive moving two-dimensional patterns often have two critical stages. In the first stage, suitable filters are convolved with the pattern over time to extract information at the "component" level. Motion energy' is then computed for each component. The second stage typically computes pattern velocity using the intersection of constraints rule (IOC). This paper describes a new implementation of the Component Level Feature Model (Bowns, 2002) that computes motion direction that is similar to these two stages except that it does not compute motion energy. Here the model computes direction for 200 randomly generated plaids. The output linearly matched that predicted by the IOC. The m... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385431 Sat, 08 Oct 2011 04:00:00 +0100 5385431 http://www.medworm.com/index.php?rid=5385430&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22005389%26dopt%3DAbstract Authors: Meijer F, Van der Lubbe RH Abstract Several studies demonstrated that active exploration as compared to passive observation of a variety of objects leads to improved performance concerning these actively studied objects later on. These results may be specifically due to an improvement in perceptual recognition but in principle they may also be due to a speeding up of responses to actively studied objects. Recently, however, it was suggested that the benefit of active exploration on perceptual recognition may be restricted to a specific class of (biologically relevant) stimuli. By employing measures derived from signal detection theory we were able to show in all our three experiments that active exploration of virtual 3D objects leads to improved perceptual sensitivity in ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385430 Sat, 08 Oct 2011 04:00:00 +0100 5385430 http://www.medworm.com/index.php?rid=5385429&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22008980%26dopt%3DAbstract Authors: Zhao L, Bentin S Abstract We explored perceptual factors that might account for the other-race classification advantage (ORCA) in classifying faces by race. Testing Chinese participants in China and Israeli participants in Israel we show that: (a) The distinction between Chinese and Israeli faces is highly accurate even on the basis of isolated eyes or faces with eyes concealed, but full faces are categorized faster. (b) The ORCA is similarly robust for full faces and for face parts. (c) The ORCA was larger when the configuration of the inner-face components was distorted, reflecting delayed categorization of own-race distorted faces relative to own-race normally configured faces but no conspicuous distortion effect on other-race faces. These data demonstrate that perceptu... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385429 Sat, 08 Oct 2011 04:00:00 +0100 5385429 http://www.medworm.com/index.php?rid=5385432&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21989227%26dopt%3DAbstract Authors: Xu JP, He ZJ, Ooi TL Abstract Sensory eye dominance (SED) reflects an imbalance of interocular inhibition in the binocular network. Extending an earlier work (Ooi & He, 2001) that measured global SED within the central 6°, the current study measured SED locally at 17 locations within the central 8° of the binocular visual field. The eccentricities (radius) chosen for this, "binocular perimetry", study were 0° (fovea), 2° and 4°. At each eccentricity, eight concentric locations (polar angle: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°) were tested. The outcome, an SED map, sets up comparison between local SED and other visual functions [monocular contrast threshold, binocular disparity threshold, reaction time to detect depth, the dynamics of binocular r... Vision Research journals http://www.medworm.com/rss/comments.php?id=5385432 Sun, 02 Oct 2011 04:00:00 +0100 5385432 http://www.medworm.com/index.php?rid=5270111&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21951519%26dopt%3DAbstract This study used the gap-overlap paradigm to examine the timing of the gaze movements by four hominid species: humans, chimpanzees, gorillas, and orangutans. The saccade latency involved in shifting the gaze from central to peripheral stimuli was measured and compared under two conditions, gap and overlap. The central stimulus disappeared shortly before the onset of the peripheral stimulus under the gap condition, but it remained under the overlap condition. Although all species demonstrated similar saccade latencies under the gap condition, the species clearly differed from one another under the overlap condition, which may suggest their similar perceptual and motor mechanism of making a saccade on the one hand and their differential strategies for coping with the competition between two a... Vision Research journals http://www.medworm.com/rss/comments.php?id=5270111 Sat, 17 Sep 2011 04:00:00 +0100 5270111 http://www.medworm.com/index.php?rid=5270114&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945645%26dopt%3DAbstract Authors: Schofield AJ, Rock PB, Georgeson MA Abstract People readily perceive smooth luminance variations as being due to the shading produced by undulations of a 3-D surface (shape-from-shading). In doing so, the visual system must simultaneously estimate the shape of the surface and the nature of the illumination. Remarkably, shape-from-shading operates even when both these properties are unknown and neither can be estimated directly from the image. In such circumstances humans are thought to adopt a default illumination model. A widely held view is that the default illuminant is a point source located above the observer's head. However, some have argued instead that the default illuminant is a diffuse source. We now present evidence that humans may adopt a flexible illumination ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5270114 Fri, 16 Sep 2011 04:00:00 +0100 5270114 http://www.medworm.com/index.php?rid=5270113&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945994%26dopt%3DAbstract Authors: Ohl S, Brandt SA, Kliegl R Abstract We examine how the size of saccadic under-/over-shoot and target eccentricity influence the latency, amplitude and orientation of secondary (micro-)saccades. In our experiment, a target appeared at an eccentricity of either 6° or 14° of visual angle. Subjects were instructed to direct their gaze as quickly as possible to the target and hold fixation at the new location until the end of the trial. Typically, increasing saccadic error is associated with faster and larger secondary saccades. We show that secondary saccades at distant in contrast to close targets have in a specific error range a shorter latency, larger amplitude, and follow more often the direction of the primary saccade. Finally, we demonstrate that an undershooting prima... Vision Research journals http://www.medworm.com/rss/comments.php?id=5270113 Fri, 16 Sep 2011 04:00:00 +0100 5270113 http://www.medworm.com/index.php?rid=5270112&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945995%26dopt%3DAbstract Authors: Morgan MJ, Chubb C, Solomon JA Abstract Adaptation to a moving stimulus changes the perception of a stationary grating and also reduces contrast sensitivity to the adaptor. We determined whether the first effect could be predicted from the second. The contrast discrimination (T vs C) function for a drifting 7.5Hz grating test stimulus was determined when observers were adapted to a low contrast (0.075) grating of the same spatial and temporal frequency, moving in either the same or the opposite direction as the test. The effect of an adaptor moving in the same direction was to move the T vs C function upwards and to the right, in a manner consistent with an increase in divisive inhibition. We also measured the effect of adaptation on the motion-null point for a counterphas... Vision Research journals http://www.medworm.com/rss/comments.php?id=5270112 Fri, 16 Sep 2011 04:00:00 +0100 5270112 http://www.medworm.com/index.php?rid=5270115&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945482%26dopt%3DAbstract Authors: Yang SN, Tai YC, Laukkanen H, Sheedy JE Abstract Transverse chromatic aberration (TCA) smears the retinal image of peripheral stimuli. We previously found that TCA significantly reduces the ability to recognize letters presented in the near fovea by degrading image quality and exacerbating crowding effect from adjacent letters. The present study examined whether TCA has a significant effect on near foveal and peripheral word identification, and whether within-word orthographic facilitation interacts with TCA effect to affect word identification. Subjects were briefly presented a 6- to 7-letter word of high or low frequency in each trial. Target words were generated with weak or strong horizontal color fringe to attenuate the TCA in the right periphery and exacerbate it in ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5270115 Sat, 10 Sep 2011 04:00:00 +0100 5270115 http://www.medworm.com/index.php?rid=5236198&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930142%26dopt%3DAbstract Authors: Nemes VA, Whitaker D, Heron J, McKeefry DJ Abstract Current models of short-term visual perceptual memory invoke mechanisms that are closely allied to low-level perceptual discrimination mechanisms. The purpose of this study was to investigate the extent to which human visual perceptual memory for spatial frequency is based upon multiple, spatially tuned channels similar to those found in the earliest stages of visual processing. To this end we measured how performance on a delayed spatial frequency discrimination paradigm was affected by the introduction of interfering or 'memory masking' stimuli of variable spatial frequency during the delay period. Masking stimuli were shown to induce shifts in the points of subjective equality (PSE) when their spatial frequencies were ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5236198 Sat, 10 Sep 2011 04:00:00 +0100 5236198 http://www.medworm.com/index.php?rid=5236199&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21925198%26dopt%3DAbstract Authors: Reuter T Abstract This review celebrates the adaptation studies published in Vision Research during the past half a century, and it is thus a complement to the anniversary issues which are focusing on more recent work (Vision Research, 51(7 and 8), 2011). Throughout the text, the discussion often starts out from a work presented in Vision Research, but the discussion is not restricted by the journals used for publication. To date, in Vision Research alone, around 500 papers related to light/dark adaptation have been published; this review tries to follow up just a few discussions within the field of vertebrate dark adaptation. The main topics are: (1) the legacies of Wald and Barlow; (2) the Dowling-Rushton relation between regenerated rhodopsin and log threshold; (3) the ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5236199 Tue, 06 Sep 2011 04:00:00 +0100 5236199 http://www.medworm.com/index.php?rid=5223603&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21911001%26dopt%3DAbstract Authors: Su J, Chen C, He D, Fang F Abstract Learning is critical for fast and efficient object recognition. However, the neural implementation of object learning in the human brain remains largely unknown. Using combined psychophysics and electroencephalogram (EEG), we investigated the effects of perceptual learning on face processing. Human subjects were trained to discriminate face views at an in-depth face orientation (i.e. 30°) over eight daily sessions, which resulted in a significant improvement in sensitivity to the trained face view. Psychophysical results showed that this improvement was highly specific to the trained view. Before and after training, we recorded subjects' EEG signals responding to the trained and the untrained face views. Analyses of event-related potent... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223603 Thu, 01 Sep 2011 04:00:00 +0100 5223603 http://www.medworm.com/index.php?rid=5223602&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21911002%26dopt%3DAbstract Authors: Hayward J, Truong G, Partanen M, Giaschi D Abstract We determined the effect of dot speed on the typical and atypical development of motion-defined form perception. Monocular motion coherence thresholds for orientation discrimination of motion-defined rectangles were determined at slow (0.1deg/s), medium (0.9deg/s) and fast (5.0deg/s) dot speeds. First we examined typical development from age 4 to 31years. We found that performance was most immature at the slow speed and in the youngest group of children (4-6years). Next we measured motion-defined form perception in the amblyopic and fellow eyes of patients with amblyopia. Deficits were found in both eyes and were most pronounced at the slow speed. These results demonstrate the importance of dot speed to the development of... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223602 Thu, 01 Sep 2011 04:00:00 +0100 5223602 http://www.medworm.com/index.php?rid=5223608&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21906613%26dopt%3DAbstract Authors: Autrusseau F, Thibos L, Shevell SK Abstract The first physiological process influencing visual perception is the optics of the eye. The retinal image is affected by diffraction at the pupil and several kinds of optical imperfections. A model of the eye (Thibos & Bradley, 1999), which takes account of pupil aperture, chromatic aberration and wavefront aberrations, was used to determine wavelength-dependent point-spread functions, which can be convolved with any stimulus specified by its spectral distribution of light at each point. The resulting retinal spectral distribution of light was used to determine the spatial distribution of stimulation for each cone type (S, M and L). In addition, individual differences in retinal-image quality were assessed using a statistical... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223608 Wed, 31 Aug 2011 04:00:00 +0100 5223608 http://www.medworm.com/index.php?rid=5223604&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21907229%26dopt%3DAbstract Authors: Lugtigheid AJ, Welchman AE Abstract Many every-day activities necessitate an estimate of the time remaining until an object will hit us: the time-to-contact (TTC). Observers' skill in estimating TTC has been studied by considering the use and combination of key visual signals (e.g. looming and disparity). However, establishing observers' proficiency in estimating TTC can be complicated, as the variable of interest (time) is typically highly correlated with other signals (e.g. target velocity or displacement). As a result, observers' responses may be based on correlates of TTC rather than on TTC itself. Here we evaluate two widely-used TTC tasks: one absolute task in which observers pressed a button to indicate the estimated TTC, and a relative task in which TTC was judged ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223604 Wed, 31 Aug 2011 04:00:00 +0100 5223604 http://www.medworm.com/index.php?rid=5223607&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21906614%26dopt%3DAbstract Authors: Zannoli M, Mamassian P Abstract The majority of natural scenes contains zones that are visible to one eye only. Past studies have shown that these monocular regions can be seen at a precise depth even though there are no binocular disparities that uniquely constrain its location in depth. In the so-called da Vinci stereopsis configuration, the monocular region is a vertical line placed next to a binocular rectangular occluder. The opacity of the occluder has been mentioned to be a necessary condition to obtain da Vinci stereopsis. However, this opacity constraint has never been empirically tested. In the present study, we tested whether da Vinci stereopsis and perceptual transparency can interact using a classical da Vinci configuration in which the opacity of the occluder... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223607 Sun, 28 Aug 2011 04:00:00 +0100 5223607 http://www.medworm.com/index.php?rid=5223606&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21906615%26dopt%3DAbstract Authors: Amir O, Biederman I, Hayworth KJ Abstract Several dimensions of shape, such as curvature or taper, can be regarded as extending from a singular (S) or 0 value (e.g., a straight contour with 0 curvature or parallel contours with a 0 angle of convergence) to an infinity of non-singular (NS) values (e.g., curves and non-parallel contours). As orientation in depth is varied, an S value remains S, and a NS value will vary but remains NS. Infant and adult human participants viewed pairs of geons where one member had an S and the other had a NS value on a given shape dimension, e.g., a cylinder vs. a cone. Both adults and infants looked first, and adults looked longer at the NS geons. The NS geons also produced greater fMRI activation in shape selective cortex (LOC), a result con... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223606 Sun, 28 Aug 2011 04:00:00 +0100 5223606 http://www.medworm.com/index.php?rid=5223605&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21906616%26dopt%3DAbstract Authors: Dearing RR, Harris LR Abstract We determined the relative effectiveness of different areas of the visual field in determining the perceptual upright. The perceptual upright was measured using the character 'p', the identity of which depended on its perceived orientation (the Oriented Character Recognition Test). The visual field was divided into left and right, upper and lower and centre and peripheral halves, with different backgrounds presented in each area. The left and right visual fields contributed equally to the perceptual upright while the lower visual field demonstrated a larger effect on the perceptual upright as compared to the upper visual field. The centre and peripheral visual fields interacted with one another in a complex manner, although a separate experim... Vision Research journals http://www.medworm.com/rss/comments.php?id=5223605 Sun, 28 Aug 2011 04:00:00 +0100 5223605 http://www.medworm.com/index.php?rid=5205944&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21893077%26dopt%3DAbstract This study quantified normal age-related changes to the photoreceptor axons in the central macula using the birefringent properties of the Henle fiber layer. A scanning laser polarimeter was used to acquire 15°×15° macular images in 120 clinically normal subjects, ranging in age from the third decade to the eighth. Raw image data of the macular cross were used to compute phase retardation maps associated with Henle fiber layer. Annular regions of interest ranging from 0.25° to 3° eccentricity and centered on the fovea were used to generate intensity profiles from the phase retardation data, which were then analyzed using sine curve fitting and Fast Fourier Transform (FFT). The amplitude of a 2f sine curve was used as a measure of macular phase retardation magnitude. For FFT analysis, ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5205944 Sat, 27 Aug 2011 04:00:00 +0100 5205944 http://www.medworm.com/index.php?rid=5205943&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21893078%26dopt%3DAbstract We present a theoretical model to estimate the influence of photopigment optical density (OD) on the color vision of anomalous trichromats. Photopigment spectral sensitivities are generated using the Lamb (1995) template, which we correct for OD and pre-receptoral filters. Sixteen hyperspectral images (Foster, Nascimento, & Amano, 2004; Nascimento, Ferreira, & Foster, 2002) are analyzed, and the signals produced in the post-receptoral channels calculated. In the case of anomalous trichromats whose two longer-wavelength cones have peak sensitivities that lie close together in the spectrum, color vision can be substantially enhanced if the cones differ in optical density by a realistic amount. PMID: 21893078 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5205943 Sat, 27 Aug 2011 04:00:00 +0100 5205943 http://www.medworm.com/index.php?rid=5182572&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21875612%26dopt%3DAbstract Authors: Donk M, van Zoest W Abstract The present study aimed to investigate whether people can selectively use salience information in search for a target. Observers were presented with a display consisting of multiple homogeneously oriented background lines and two orientation singletons. The orientation singletons differed in salience, where salience was defined by their orientation contrast relative to the background lines. Observers had the task to make a speeded eye movement towards a target, which was either the most or the least salient element of the two orientation singletons. The specific orientation of the target was either constant or variable over a block of trials such that observers had varying knowledge concerning the target identity. The results demonstrated that ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5182572 Sun, 21 Aug 2011 23:00:00 +0100 5182572 http://www.medworm.com/index.php?rid=5182574&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21871476%26dopt%3DAbstract Authors: Zhang B, Pansell T, Ygge J, Bolzani R Abstract A slow oscillatory movement (SOM) has previously been discovered superimposed on the three well known components of fixational eye movements. The purpose of the present study was to explore the visual influence on the control mechanism of the SOM. Three tests with different fixation targets and backgrounds were prepared. The eye position during a fixation task on healthy test subjects has been recorded by the Chronos eye tracking device. The visual stimuli with no or less information triggered larger SOM amplitudes. None of the investigated conditions significantly influenced on SOM frequency. PMID: 21871476 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5182574 Wed, 17 Aug 2011 23:00:00 +0100 5182574 http://www.medworm.com/index.php?rid=5182573&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21871912%26dopt%3DAbstract Authors: Gias C, Vugler A, Lawrence J, Carr AJ, Chen LL, Ahmado A, Semo M, Coffey PJ Abstract The purpose of the current study was to determine the progress of cortical functional degeneration in the Royal College of Surgeons (RCS) rat. Cortical responses were measured with optical imaging of intrinsic signals using gratings of various spatial frequencies. Subsequently, electrophysiological recordings were also taken across cortical layers in response to a pulse of broad-spectrum light. We found significant degeneration in the cortical processing of visual information as early as 4weeks of age. These results show that degeneration in the cortical response of the RCS rat starts before development has been properly completed. PMID: 21871912 [PubMed - as supplied by publisher] (So... Vision Research journals http://www.medworm.com/rss/comments.php?id=5182573 Wed, 17 Aug 2011 23:00:00 +0100 5182573 http://www.medworm.com/index.php?rid=5168752&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864558%26dopt%3DAbstract Authors: Chui TY, Zhong Z, Burns SA Abstract We evaluated the relationship between the size of the peripapillary crescent and the axial length (AL) of the eye as well as the fine structure of the peripapillary crescent in selected eyes. Infrared fundus imaging and spectral domain optical coherence tomography (SDOCT) (Spectralis HRA+OCT, Heidelberg Engineering, Germany) centered at the fovea were performed on 72 healthy adults. On the infrared fundus images, we measured (a) the distance between the foveola and the temporal edge of the optic disc (FOD) and (b) the distance between the foveola and the temporal edge of the peripapillary crescent (FOC) (if present). A peripapillary crescent presented at the nasal margin of the disc in 64% of the subjects. The FOD and FOC were 4.22mm±0.... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168752 Mon, 15 Aug 2011 23:00:00 +0100 5168752 http://www.medworm.com/index.php?rid=5168751&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864559%26dopt%3DAbstract Authors: Ozbek M, Bindemann M Abstract The identification of unfamiliar faces has been studied extensively with matching tasks, in which observers decide if pairs of photographs depict the same person (identity matches) or different people (mismatches). In experimental studies in this field, performance is usually self-paced under the assumption that this will encourage best-possible accuracy. Here, we examined the temporal characteristics of this task by limiting display times and tracking observers' eye movements. Observers were required to make match/mismatch decisions to pairs of faces shown for 200, 500, 1000, or 2000ms, or for an unlimited duration. Peak accuracy was reached within 2000ms and two fixations to each face. However, intermixing exposure conditions produced a cont... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168751 Mon, 15 Aug 2011 23:00:00 +0100 5168751 http://www.medworm.com/index.php?rid=5168750&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864560%26dopt%3DAbstract Authors: Bavelier D, Achtman RL, Mani M, Föcker J Abstract Over the past few years, the very act of playing action video games has been shown to enhance several different aspects of visual selective attention. Yet little is known about the neural mechanisms that mediate such attentional benefits. A review of the aspects of attention enhanced in action game players suggests there are changes in the mechanisms that control attention allocation and its efficiency (Hubert-Wallander, Green, & Bavelier, 2010). The present study used brain imaging to test this hypothesis by comparing attentional network recruitment and distractor processing in action gamers versus non-gamers as attentional demands increased. Moving distractors were found to elicit lesser activation of the visual moti... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168750 Mon, 15 Aug 2011 23:00:00 +0100 5168750 http://www.medworm.com/index.php?rid=5168749&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864561%26dopt%3DAbstract Authors: Kogo N, Galli A, Wagemans J Abstract A model that computes the border-ownership (BOWN) and the depth map of the image (DISC model, Kogo et al., 2010) is applied to investigate the stochastic nature of perception in "face or vase" stimuli. The 2-D integration of BOWN signals determines the figure-ground relationships in the image. In the present application of the model, BOWN signals are made stochastic and feedback connections are established between the higher level depth perception and the lower level BOWN signals. This feedback modifies the BOWN signals to further enhance the figure-ground segregation. Adaptation results in a decay of the response which leads to alternation. This triggers recovery of the adaptation. The alternation rate decreases in response to the incr... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168749 Mon, 15 Aug 2011 23:00:00 +0100 5168749 http://www.medworm.com/index.php?rid=5168753&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21856327%26dopt%3DAbstract Authors: Petrov AA, Van Horn NM Abstract The representation modification hypothesis of perceptual learning attributes the practice-induced improvements in sensitivity and/or discriminability to changes in the early visual areas. We used motion aftereffects (MAE) to probe the representations of motion direction. In two experiments, four practice sessions on a fine direction-discrimination task caused large stimulus-specific improvements in d' but no significant stimulus-specific changes in either static or dynamic MAE duration at posttest relative to a pretest. Power analysis indicated that the data were approximately 100 times more likely given the hypothesis of no MAE change than the hypothesis of a 10% relative change. In light of converging evidence in the MAE literature, this s... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168753 Thu, 11 Aug 2011 23:00:00 +0100 5168753 http://www.medworm.com/index.php?rid=5168755&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21854801%26dopt%3DAbstract Authors: Meinhardt-Injac B, Persike M, Meinhardt G Abstract Faces are perceived holistically, even when they are presented briefly (Hole, 1994; Richler, Mack, et al., 2009). Results obtained with a context congruency paradigm supports dominance of holistic processing for brief timings, but indicates that larger viewing times enable observers to regulate contextual influences, and to use a feature selective focus (Meinhardt-Injac, Persike, & Meinhardt, 2010). Here we provide further evidence for this claim, and illuminate the role of feedback. With trial by trial feedback observers show poor performance in incongruent facial contexts at brief timings, but become quite effective in suppressing information that interferes with the correct judgements at larger viewing times. Withou... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168755 Tue, 09 Aug 2011 23:00:00 +0100 5168755 http://www.medworm.com/index.php?rid=5168754&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21855560%26dopt%3DAbstract Authors: Amiaz R, Zomet A, Polat U Abstract Collinear flankers increase the reports of the target present, an effect attributed to excitatory activation induced by the flankers on the target location, which consequently induces the filling-in effect (Polat & Sagi, 2007). Repetitive transcranial magnetic stimulation (rTMS) is a powerful tool for non-invasive investigation of neural processing in the human brain. We explored how rTMS over the left dorsolateral prefrontal cortex (LDLPFC) affects filling-in perception in normal controls. Active and Sham rTMS were used over the DLPFC (90% of the subjects' motor threshold (MT)) using 10-Hz pulses for 5- and 20-s intertrain intervals. We used the filling-in paradigm to probe hit rates (pHit) and false-positive reports (false alarm, pF... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168754 Tue, 09 Aug 2011 23:00:00 +0100 5168754 http://www.medworm.com/index.php?rid=5168757&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21854799%26dopt%3DAbstract This study examined the relationship between cerebral white matter microstructure, evaluated by diffusion tensor imaging (DTI), and visual function, in 30 preterm born adolescents with very low birth weight (VLBW=birth weight⩽1500g) and an age-matched group of 45 term born controls. Visual acuity correlated positively with fractional anisotropy (FA) in corpus callosum and in frontal white matter areas in the VLBW participants, but not in the control participants. Callosal visual connections may play a more important role in the development of good visual acuity than previously acknowledged in preterm born children. PMID: 21854799 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5168757 Mon, 08 Aug 2011 23:00:00 +0100 5168757 http://www.medworm.com/index.php?rid=5168756&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21854800%26dopt%3DAbstract Authors: Kwon M, Legge GE Abstract It is well known that object recognition requires spatial frequencies exceeding some critical cutoff value. People with central scotomas who rely on peripheral vision have substantial difficulty with reading and face recognition. Deficiencies of pattern recognition in peripheral vision, might result in higher cutoff requirements, and may contribute to the functional problems of people with central-field loss. Here we asked about differences in spatial-cutoff requirements in central and peripheral vision for letter and face recognition. The stimuli were the 26 letters of the English alphabet and 26 celebrity faces. Each image was blurred using a low-pass filter in the spatial frequency domain. Critical cutoffs (defined as the minimum low-pass filte... Vision Research journals http://www.medworm.com/rss/comments.php?id=5168756 Mon, 08 Aug 2011 23:00:00 +0100 5168756 http://www.medworm.com/index.php?rid=5146212&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21846478%26dopt%3DAbstract Authors: Pavan A, Casco C, Mather G, Bellacosa RM, Cuturi LF, Campana G Abstract A series of experiments investigated the extent to which the spatial orientation of a signal line affects discrimination of its trajectory from the random trajectories of background noise lines. The orientation of the signal line was either parallel (iso-) or orthogonal (ortho-) to its motion direction and it was identical in all respects to the noise (orientation, length and speed) except for its motion direction, rendering the signal line indistinguishable from the noise on a frame-to-frame basis. We found that discrimination of ortho-trajectories was generally better than iso-trajectories. Discrimination of ortho-trajectories was largely immune to the effects of spatial jitter in the trajectory, and... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146212 Mon, 08 Aug 2011 23:00:00 +0100 5146212 http://www.medworm.com/index.php?rid=5146213&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21843544%26dopt%3DAbstract Authors: Norman LJ, Heywood CA, Kentridge RW Abstract Regions of visual texture can be automatically segregated from one another when they abut but also discriminated from one another if they are separated in space or time. A difference in mean orientation between two textures serves to facilitate their segmentation, whereas a difference in orientation variance does not. The present study further supports this notion, by replicating the findings of Wolfson and Landy (1998) in showing that judgments (odd-one-out) made for textures that differ in mean orientation were more accurate (and more rapid) when the textures were abutting than when separated, whereas judgments of variance were made no more accurately for abutting relative to separated textures. Interestingly, however, respons... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146213 Fri, 05 Aug 2011 23:00:00 +0100 5146213 http://www.medworm.com/index.php?rid=5146216&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21840332%26dopt%3DAbstract Authors: Xu S, Zhang S, Geng H Abstract The automaticity of gaze-induced joint attention is well known in relatively easy cognitive tasks; but its role in harder tasks had never been examined. This encouraged us to study automaticity in hard tasks, tasks presenting the subjects with high perceptual loads. The Rapid Serial Visual Presentation (RSVP) paradigm was used to present participants with two streams of bilaterally displayed digit-flows while they fixated at the center of a synthetic representation of a human face. The face was presented both above (Experiments 1 and 2) and below (Experiment 3) the face's visual threshold (henceforth called "supraliminal" and "subliminal", respectively). Interocular suppression was used to make the face stimulus invisible (subliminal). In the... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146216 Thu, 04 Aug 2011 23:00:00 +0100 5146216 http://www.medworm.com/index.php?rid=5146215&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21840333%26dopt%3DAbstract Authors: Norman JF, Holmin JS, Bartholomew AN Abstract Three experiments compared younger (mean age was 23.7years) and older (mean age was 72.1years) observers' ability to visually discriminate line length using both explicit and implicit standard stimuli. In Experiment 1, the method of constant stimuli (with an explicit standard) was used to determine difference thresholds, whereas the method of single stimuli (where the knowledge of the standard length was only implicit and learned from previous test stimuli) was used in Experiments 2 and 3. The study evaluated whether increases in age affect older observers' ability to learn, retain, and utilize effective implicit visual standards. Overall, the observers' length difference thresholds were 5.85% of the standard when the method of... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146215 Thu, 04 Aug 2011 23:00:00 +0100 5146215 http://www.medworm.com/index.php?rid=5146214&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21840334%26dopt%3DAbstract Authors: Simmers AJ, Ledgeway T, Hutchinson CV, Knox PJ Abstract It is well established that amblyopes exhibit deficits in processing first-order (luminance-defined) patterns. This is readily manifest by measuring spatiotemporal sensitivity (i.e. the "window of visibility") to moving luminance gratings. However the window of visibility to moving second-order (texture-defined) patterns has not been systematically studied in amblyopia. To address this issue monocular modulation sensitivity (1/threshold) to first-order motion and four different varieties of second-order motion (modulations of either the contrast, flicker, size or orientation of visual noise) was measured over a five-octave range of spatial and temporal frequencies. Compared to normals amblyopes are not only impaired i... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146214 Thu, 04 Aug 2011 23:00:00 +0100 5146214 http://www.medworm.com/index.php?rid=5146217&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21839107%26dopt%3DAbstract Authors: Morgan MJ Abstract We determined whether distracting the observer's attention from an adapting stimulus could decrease the motion after-effect. Unlike previous studies we used a relatively bias-free 2AFC procedure to measure the strength of adaptation. The strength of motion adaptation was measured by the effects of a moving grating on the contrast discrimination (T vs. C) function for gratings moving in the same or opposite direction. As in previous reports, the effect of adaptation was to move the T vs. C function upwards and rightwards, consistent with an increase in the C50 (semi-saturation) response in the transduction function of the neural mechanism underlying the discrimination. On the other hand, manipulating the attentional load of a distracting task during adapt... Vision Research journals http://www.medworm.com/rss/comments.php?id=5146217 Sat, 30 Jul 2011 23:00:00 +0100 5146217 http://www.medworm.com/index.php?rid=5126328&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21801742%26dopt%3DAbstract Authors: Sasaki R, Uka T Human judgment is frequently impaired by distracters extending across our field of view. How we extract relevant information from a spatially restricted region in a complex scene in spite of this impairment is an important issue in vision. Recently, it has been shown that this impairment can be reduced by increasing the number of surrounding distracters without changing the density, thus increasing the total area covered by the distracters. Little, however, is known regarding the underlying mechanism(s). Here, we tested the hypothesis that visual impairment by distracters is due to integration of irrelevant information across space, and that further addition of distracters produces contraction of the spatial integration field. Human subjects were instructed to ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126328 Tue, 26 Jul 2011 23:00:00 +0100 5126328 http://www.medworm.com/index.php?rid=5126288&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21820002%26dopt%3DAbstract Authors: Fesi JD, Yannes MP, Brinckman DD, Norcia AM, Ales JM, Gilmore RO Motion contrast contributes to the segregation of a two-dimensional figure from its background, yet many questions remain about its neural mechanisms. We measured steady-state visual evoked potential (SSVEP) responses to moving dot displays in which figure regions emerged from and disappeared into the background at a specific temporal frequency (1.2Hz, F1), based on regional differences of dot direction and global direction coherence. The goal was to measure the cortical response function across a range of motion contrast magnitudes. In two experiments using both a low channel count electrode array (Experiment 1) and a high density array (Experiment 2), we observed two distinct phase-locked evoked responses that ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126288 Mon, 25 Jul 2011 23:00:00 +0100 5126288 http://www.medworm.com/index.php?rid=5126279&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21820003%26dopt%3DAbstract Authors: Underwood G, Humphrey K, van Loon E Evidence from eye-tracking experiments has provided mixed support for saliency map models of inspection, with the task set for the viewer accounting for some of the discrepancies between predictions and observations. In the present experiment viewers inspected pictures of road scenes with the task being to decide whether or not they would enter a highway from a junction. Road safety observations have concluded that highly visible road users are less likely to be involved in crashes, suggesting that saliency is important in real-world tasks. The saliency of a critical vehicle was varied in the present task, as was the type of vehicle and the preferred vehicle of the viewer. Decisions were influenced by saliency, with more risky decisions when... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126279 Mon, 25 Jul 2011 23:00:00 +0100 5126279 http://www.medworm.com/index.php?rid=5126269&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21820004%26dopt%3DAbstract Authors: Wang R, Zhang JY, Klein SA, Levi DM, Yu C Location-specific perceptual learning can be rendered transferrable to a new location with double training, in which feature training (e.g., contrast) is accompanied by additional location training at the new location even with an irrelevant task (e.g. orientation). Here we investigated the impact of relevancy (to feature training) and demand of location training tasks on double training enabled learning transfer. We found that location training with an irrelevant task (Gabor vs. letter judgment, or contrast discrimination) limited transfer of Vernier learning to the trained orientation only. However, performing a relevant suprathreshold orthogonal Vernier task prompted additional transfer to an untrained orthogonal orientation. In add... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126269 Mon, 25 Jul 2011 23:00:00 +0100 5126269 http://www.medworm.com/index.php?rid=5126297&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21810439%26dopt%3DAbstract Authors: Leclercq V, Seitz AR The basic phenomenon of task-irrelevant perceptual learning (TIPL) is that the stimulus features of a subject's task will be learned when they are consistently presented at times of reward or behavioral success. Recent progress in studies of TIPL has been made by the discovery of a fast form of TIPL (fast-TIPL), which can be observed with as little as a single trial of exposure. In the present study, we investigated the task-conditions required to observe fast-TIPL. We had participants perform a target detection task at fixation while scenes to memorize were presented peripherally. In some experiments the target was presented in a sequence of distractors (Experiments 2 and 4) and in others alone (Experiments 1 and 3). In each experiment we assessed whether... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126297 Sat, 23 Jul 2011 23:00:00 +0100 5126297 http://www.medworm.com/index.php?rid=5126322&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807016%26dopt%3DAbstract Authors: Bower JD, Andersen GJ In the present study we examined the use of perceptual learning to improve motion processing in older and younger individuals. Using the Perceptual Template Model (Lu & Dosher, 1998, 1999), age-related differences in baseline perceptual inefficiencies and changes due to training were assessed for additive internal noise, tolerance to external noise, and internal multiplicative noise. In Experiments 1 and 2 we trained participants by manipulating contrast in noise embedded sine-wave gratings and Random Dot Cinematograms (RDCs). The results indicate that older observers have higher additive internal noise and lower tolerance to external noise compared to younger observers. The rate of perceptual learning in older observers was found to be similar to tha... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126322 Fri, 22 Jul 2011 23:00:00 +0100 5126322 http://www.medworm.com/index.php?rid=5126316&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21807017%26dopt%3DAbstract Authors: Daddaoua N, Dicke PW, Thier P To investigate the effect of head roll tilt on the binocular coordination of ocular counterroll in non-human primates, we measured binocular ocular counterroll in two rhesus monkeys fixating a straight ahead target, while adopting different head roll tilt positions. We used two infrared cameras to take snapshots of the left and the right eye in order to measure the resulting ocular counterroll responses. The horizontal and vertical components of the position of one of the two eyes where measured using an implanted 2D-search coil in one monkey and video-based eye tracking in the second one. We consistently observed disconjugate ocular counterroll responses to static head roll in both monkeys. Invariably, the eye positioned further away from ground ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126316 Fri, 22 Jul 2011 23:00:00 +0100 5126316 http://www.medworm.com/index.php?rid=5126306&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21810438%26dopt%3DAbstract Authors: Zhao C, Seriès P, Hancock PJ, Bednar JA Visual aftereffects have been found for a wide variety of stimuli, ranging from oriented lines to human faces, but previous results suggested that face aftereffects were qualitatively different from orientation (tilt) aftereffects. Using computational models, we predicted that these differences were due to the limited range of faces used in previous studies. Here we report psychophysical results verifying this prediction. We used the same paradigm to test tilt aftereffects (TAE) and face gender aftereffects (FAE) and found that they exhibited qualitatively similar aftereffect curves, when a sufficiently large range of test faces was used. Overall, the results suggest that similar adaptation mechanisms may underlie both high-level and lo... Vision Research journals http://www.medworm.com/rss/comments.php?id=5126306 Fri, 22 Jul 2011 23:00:00 +0100 5126306 http://www.medworm.com/index.php?rid=5078248&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21784095%26dopt%3DAbstract Authors: Foulsham T, Walker E, Kingstone A How do people distribute their visual attention in the natural environment? We and our colleagues have usually addressed this question by showing pictures, photographs or videos of natural scenes under controlled conditions and recording participants' eye movements as they view them. In the present study, we investigated whether people distribute their gaze in the same way when they are immersed and moving in the world compared to when they view video clips taken from the perspective of a walker. Participants wore a mobile eye tracker while walking to buy a coffee, a trip that required a short walk outdoors through the university campus. They subsequently watched first-person videos of the walk in the lab. Our results focused on where people d... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078248 Wed, 20 Jul 2011 23:00:00 +0100 5078248 http://www.medworm.com/index.php?rid=5078250&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21784093%26dopt%3DAbstract Authors: Lamy D, Zivony A, Yashar A Previous research has shown that intertrial repetition of target and distractors task-relevant properties speeds visual search performance, an effect known as priming of pop-out (PoP). Recent accounts suggest that such priming results, at least in part, from a mechanism that speeds post-selectional, response-related processes, the marker of which is an interaction between repetition of the target and distractor features and repetition of the response from the previous trial. However, this response-based component of inter-trial priming has been elusive, and it remains unclear what its boundary conditions might be. In addition, what information is represented in the episodic memory traces that underlie the response-based component has not yet been cha... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078250 Mon, 18 Jul 2011 23:00:00 +0100 5078250 http://www.medworm.com/index.php?rid=5078249&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21784094%26dopt%3DAbstract Authors: Pilz KS, Konar Y, Vuong QC, Bennett PJ, Sekuler AB Object recognition is an important visual process. We are not only required to recognize objects across a variety of lighting conditions and variations in size, but also across changes in viewpoint. It has been shown that reaction times in object matching increase as a function of increasing angular disparity between two views of the same object, and it is thought that this is related to the time it takes to mentally rotate an object. Recent studies have shown that object rotations for familiar objects affect older subjects differently than younger subjects. To investigate the general normalization effects for recognizing objects across different viewpoints regardless of visual experience with an object, in the current study w... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078249 Mon, 18 Jul 2011 23:00:00 +0100 5078249 http://www.medworm.com/index.php?rid=5078246&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21787801%26dopt%3DAbstract Authors: Thurgood C, Whitfield TW, Patterson J The human visual system is very adept at extracting categorical information from complex scenes with only the briefest of exposure. Here we show that information from visual scenes can be processed to the level of identification with formally unattainable, ultra-brief (1ms) presentations. This brief presentation time is afforded by a new instrument, the light-emitting diode (LED) tachistoscope, in which a liquid crystal display (LCD) is illuminated externally by a brief LED flash after LCD steady-state is reached, such that image onset and offset timing can be precisely controlled. Photographs of animals were presented with or without backgrounds for 1ms and 10ms. The results indicate that visual recognition of objects benefits from presen... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078246 Mon, 18 Jul 2011 23:00:00 +0100 5078246 http://www.medworm.com/index.php?rid=5078251&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21782839%26dopt%3DAbstract Authors: Brascamp JW, Pels E, Kristjánsson A When target-color repeats in pop-out visual search performance is faster than otherwise. While various characteristics of such priming of pop-out (PoP) are well known, relatively little is known about the temporal character of the memory traces underlying the effect. Recent findings on the perception of ambiguous stimuli show that the percept at any given moment is affected by perception over a long period, as well as by immediately preceding percepts. Intrigued by the existence of various parallels between this perceptual priming phenomenon and PoP, we here investigate whether similar multiplicity in timescales is seen for PoP. We contrasted long-term PoP build-up of a particular target color against shorter-term build-up for a different c... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078251 Sun, 17 Jul 2011 23:00:00 +0100 5078251 http://www.medworm.com/index.php?rid=5078254&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21777599%26dopt%3DAbstract Authors: Holmes SA, Mulla A, Binsted G, Heath M The 'just noticeable difference' (JND) represents the minimum amount by which a stimulus must change to produce a noticeable variation in one's perceptual experience and is related to initial stimulus magnitude (i.e., Weber's law). The goal of the present study was to determine whether aperture shaping for visually derived and memory-guided grasping elicit a temporally dependent or temporally independent adherence to Weber's law. Participants were instructed to grasp differently sized objects (20, 30, 40, 50 and 60mm) in conditions wherein vision of the grasping environment was available throughout the response (i.e., closed-loop), when occluded at movement onset (i.e., open-loop), and when occluded for a brief (i.e., 0ms) or longer (i.e.... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078254 Wed, 13 Jul 2011 23:00:00 +0100 5078254 http://www.medworm.com/index.php?rid=5078253&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21777600%26dopt%3DAbstract Authors: Raidvee A, Averin K, Kreegipuu K, Allik J Six observers were asked to indicate in which of two opposite directions, to the right or to the left, an entire display appeared to move, based on the proportion of right vs leftward motion elements, each of which was distinctly visible. The performance of each observer was described by Thurstone's discriminative processes and Bernoulli trial models which described empirical psychometric functions equally well. Although formally it was impossible to discriminate between these two models, treating observer as a counting device which measures a randomly selected subsample of all available motion elements had certain advantages. According to the Bernoulli trial model decisions about the global motion direction in a range of 12-800 elemen... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078253 Wed, 13 Jul 2011 23:00:00 +0100 5078253 http://www.medworm.com/index.php?rid=5078252&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21777601%26dopt%3DAbstract Authors: Martin J, Vasudevan B, Himebaugh N, Bradley A, Thibos L To identify unbiased methods for estimating the target vergence required to maximize visual acuity based on wavefront aberration measurements. Experiments were designed to minimize the impact of confounding factors that have hampered previous research. Objective wavefront refractions and subjective acuity refractions were obtained for the same monochromatic wavelength. Accommodation and pupil fluctuations were eliminated by cycloplegia. Unbiased subjective refractions that maximize visual acuity for high contrast letters were performed with a computer controlled forced choice staircase procedure, using 0.125 diopter steps of defocus. All experiments were performed for two pupil diameters (3mm and 6mm). As reported in the ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078252 Wed, 13 Jul 2011 23:00:00 +0100 5078252 http://www.medworm.com/index.php?rid=5078258&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21763711%26dopt%3DAbstract Authors: Beardsley SA, Sikoglu EM, Hecht H, Vaina LM We assessed the effect of the coherence of optic flow on time-to-passage judgments in order to investigate the strategies that observers use when local expansion information is reduced or lacking. In the standard display, we presented a cloud of dots whose image expanded consistent with constant observer motion. The dots themselves, however, did not expand and were thus devoid of object expansion cues. Only the separations between the dots expanded. Subjects had to judge which of two colored target dots, presented at different simulated depths and lateral displacements would pass them first. Image velocities of the target dots were chosen so as to correlate with time-to-passage only some of the time. When optic flow was mainly incohe... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078258 Thu, 07 Jul 2011 23:00:00 +0100 5078258 http://www.medworm.com/index.php?rid=5078256&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21763713%26dopt%3DAbstract Authors: Pell PJ, Richards A Increasing evidence suggests that the visual representations of different emotional facial expressions overlap. Here we used an adaptation paradigm to investigate overlap of anger, disgust and fear expressions. In Experiment 1, participants categorized faces morphed from neutral to anger or neutral to disgust after adaptation to expressions of anger, disgust, and fear. Adaptation to expressions of both anger and disgust was found to bias perception of anger expressions away from anger. For disgust expressions, adaptation to disgust biased perception away from disgust, whereas fear adaptation biased perception towards disgust. Adaptation to anger had no measurable effect. In Experiment 2, covering the mouth-region of the disgust adaptation face was found to ... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078256 Thu, 07 Jul 2011 23:00:00 +0100 5078256 http://www.medworm.com/index.php?rid=5078255&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21767561%26dopt%3DAbstract Authors: Aydın M, Herzog MH, Oğmen H When objects move in the environment, their retinal images can undergo drastic changes and features of different objects can be inter-mixed in the retinal image. Notwithstanding these changes and ambiguities, the visual system is capable of establishing correctly feature-object relationships as well as maintaining individual identities of objects through space and time. Recently, by using the Ternus-Pikler display, we have shown that perceived motion correspondences serve as the medium for non-retinotopic attribution of features to objects. The purpose of the work reported in this manuscript was to assess whether perceived motion correspondences provide a sufficient condition for feature attribution. Our results show that the introduction of a sta... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078255 Thu, 07 Jul 2011 23:00:00 +0100 5078255 http://www.medworm.com/index.php?rid=5078259&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21763339%26dopt%3DAbstract Authors: Blakeslee B, McCourt ME Brightness induction refers to a class of visual illusions in which the perceived intensity of a region of space is influenced by the luminance of surrounding regions. These illusions are significant because they provide insight into the neural organization of the visual system. A novel quadrature-phase motion cancelation technique was developed to measure the magnitude of the grating induction brightness illusion across a wide range of spatial frequencies, temporal frequencies and test field heights. Canceling contrast is greatest at low frequencies and declines with increasing frequency in both dimensions, and with increasing test field height. Canceling contrast scales as the product of inducing grating spatial frequency and test field height (the nu... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078259 Wed, 06 Jul 2011 23:00:00 +0100 5078259 http://www.medworm.com/index.php?rid=5078257&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21763712%26dopt%3DAbstract In this study, we designed a 9-channel microelectrode array and implanted it between dura mater and pia mater of rabbit ONs by lateral orbitotomy. We recorded the current thresholds and evaluated the efficacy of the array using electrically evoked potentials (EEPs). Spatial discrimination of approximately 20° was verified by EEP maps over visual cortex. A large area of visual field (over 130° along horizontal meridian) could be activated by this microelectrode array. Visual evoked potentials (VEPs) and different pathological examinations were used to examine possible damage of ONs. One year post implantation, we did not notice significant damages to both ONs and the microelectrode arrays. EEPs were successfully recorded up to 6months post implantations. However, further studies are still... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078257 Wed, 06 Jul 2011 23:00:00 +0100 5078257 http://www.medworm.com/index.php?rid=5078260&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21762715%26dopt%3DAbstract Authors: Howard CJ, Masom D, Holcombe AO In the multiple object tracking (MOT) task, observers can typically keep track of up to four moving objects. Little is known however about the extent to which object motion is used by observers during MOT. For example, direction and speed might be used to anticipate future positions. We here ask to what extent position reports lag behind targets or instead correspond to extrapolated positions. Using a range of different motion trajectory patterns, observers tracked 1-4 targets among distracters and reported the final position of one of the targets. On average, reports corresponded to previous positions rather than the final position. This lag varied across conditions from around 10 to 70ms of the object's trajectory. Although some have suggested... Vision Research journals http://www.medworm.com/rss/comments.php?id=5078260 Tue, 05 Jul 2011 23:00:00 +0100 5078260 http://www.medworm.com/index.php?rid=5078247&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21784239%26dopt%3DAbstract Authors: Shevell S, Hood D, Martin P, Morrone C, Levi D PMID: 21784239 [PubMed - in process] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5078247 Thu, 30 Jun 2011 23:00:00 +0100 5078247 http://www.medworm.com/index.php?rid=5029487&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21745493%26dopt%3DAbstract Authors: Jainta S, Bucci MP, Wiener-Vacher S, Kapoula Z Vergence insufficiency is frequent in many populations including children with vertigo in the absence of measurable vestibular dysfunction. Orthoptic exercises are typically used to improve vergence and the clinical practice suggests that simple repetition of vergence movements improves it. Objective eye movement recordings were used to asses the dynamics and spatial-temporal properties of convergence (8.7°) and divergence (2.7°) along the midline while these movements were repeated 80 times. Eight children, aged on average 13years and showing vertigo symptoms accompanied with vergence insufficiency, participated. For both, convergence and divergence the velocity increased and the overall duration decreased; the amplitude of the... Vision Research journals http://www.medworm.com/rss/comments.php?id=5029487 Thu, 30 Jun 2011 23:00:00 +0100 5029487 http://www.medworm.com/index.php?rid=5029486&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21745494%26dopt%3DAbstract Authors: D'Antona AD, Kremers J, Shevell SK The percept of a time-varying light depends on the temporal properties of light within the surrounding area. The locus of the neural mechanism mediating this lateral interaction is controversial; neural mechanisms have been posited at the LGN (Kremers et al., 2004) or cortical level (D'Antona & Shevell, 2007). To determine the neural locus, changes in perceived temporal variation were compared with ipsilateral versus contralateral surrounding context. In both cases, a temporally varying central field was viewed within a temporally varying surround; relative phase between center and surround was varied. Perceived modulation depth in the central field depended strongly on the relative phase between center and surround, in both the ipsilater... Vision Research journals http://www.medworm.com/rss/comments.php?id=5029486 Thu, 30 Jun 2011 23:00:00 +0100 5029486 http://www.medworm.com/index.php?rid=5029488&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21723311%26dopt%3DAbstract Authors: Ries AJ, Hopfinger JB Previous studies have provided conflicting evidence regarding whether the magnocellular (M) or parvocellular (P) visual pathway is primarily responsible for triggering involuntary orienting. Here, we used event-related potentials (ERPs) to provide new evidence that both the M and P pathways can trigger attentional capture and bias visual processing at multiple levels. Specifically, cued-location targets elicited enhanced activity, relative to uncued-location targets, at both early sensory processing levels (indexed by the P1 component) and later higher-order processing stages (as indexed by the P300 component). Furthermore, the present results show these effects of attentional capture were not contingent on the feature congruency between the cue and expec... Vision Research journals http://www.medworm.com/rss/comments.php?id=5029488 Wed, 22 Jun 2011 23:00:00 +0100 5029488 http://www.medworm.com/index.php?rid=5029489&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21722662%26dopt%3DAbstract This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3μm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelber... Vision Research journals http://www.medworm.com/rss/comments.php?id=5029489 Tue, 21 Jun 2011 23:00:00 +0100 5029489 http://www.medworm.com/index.php?rid=5029490&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21722661%26dopt%3DAbstract In this study, we measured static (SVA) and dynamic visual acuity (DVA) in the central and peripheral visual field on healthy, young emmetropic subjects using stationary and drifting Gabor patches. There were no differences between SVA and DVA in the peripheral visual field; however, SVA was superior to DVA in the fovea for both velocities tested. In addition, there was a clear naso-temporal asymmetry for both SVA and DVA for isoeccentric locations in the visual field beyond 10° eccentricity. The lack of difference in visual acuity between static and dynamic stimuli found in this study may reflect the use of drift-motion as opposed to displacement motion used in previous studies. PMID: 21722661 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=5029490 Mon, 20 Jun 2011 23:00:00 +0100 5029490 http://www.medworm.com/index.php?rid=4983814&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21703293%26dopt%3DAbstract Authors: Michael L, Hesselmann G, Kiefer M, Niedeggen M The conscious perception of simple visual stimuli can be modulated by the presence of distractors. In the motion blindness paradigm, the detection of coherent motion is impaired when task-irrelevant motion distractors are presented prior to the target. Aim of this study was to examine the feature specificity of the distractor effect. For this reason, targets were either defined by motion coherence ("motion blindness") or orientation changes ("orientation blindness"). In a series of three experiments we show that distractors have to share the feature characteristics of the target in order to reduce its detectability. However, independent inhibition sets for visual features can be activated if the targets' characteristics are ambigu... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983814 Wed, 15 Jun 2011 23:00:00 +0100 4983814 http://www.medworm.com/index.php?rid=4983810&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704056%26dopt%3DAbstract Authors: Bell J, Gheorghiu E, Hess RF, Kingdom FA Radial Frequency (RF) patterns can be used to study the processing of familiar shapes, e.g. triangles and squares. Opinion is divided over whether the mechanisms that detect these shapes integrate local orientation and position information directly, or whether local orientations and positions are first combined to represent extended features, such as curves, and that it is local curvatures that the shape mechanism integrates. The latter view incorporates an intermediate processing stage, the former does not. To differentiate between these hypotheses we studied the processing of micro-patch sampled RF patterns as a function of the luminance polarity of successive elements on the contour path. Our first study measures shape after effects ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983810 Wed, 15 Jun 2011 23:00:00 +0100 4983810 http://www.medworm.com/index.php?rid=4983809&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704057%26dopt%3DAbstract Authors: Gardiner SK, Demirel S, Johnson CA, Swanson WH Currently, global indices that summarize the visual field combine sensitivities on a logarithmic (decibel) scale. Recent structure-function models for glaucoma suggest that contrast sensitivity should be converted to a linear scale before averaging across visual field locations, to better relate sensitivity with the number of surviving retinal ganglion cells (RGCs). New indices designed to represent the number of RGCs already lost are described. At least one was found to be a significantly better predictor of subsequent rate of change than traditional Mean Deviation (p=0.014) in participants with glaucomatous optic neuropathy. Issues concerning the creation of optimal global indices are discussed. PMID: 21704057 [PubMed - as s... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983809 Wed, 15 Jun 2011 23:00:00 +0100 4983809 http://www.medworm.com/index.php?rid=4983808&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704058%26dopt%3DAbstract Authors: Tavassoli T, Latham K, Bach M, Dakin SC, Baron-Cohen S Previously reported superior visual acuity (VA) in autism spectrum conditions (ASC) may have resulted from methodological settings used (Ashwin, Ashwin, Rhydderch, Howells, & Baron-Cohen, 2009). The current study re-tested whether participants with (N=20) and without (N=20) ASC differ on psychophysical measures of VA. Participants' vision was corrected before acuity measurement, minimising refractive blur. VA was assessed with an ETDRS chart as well as the Freiburg Visual Acuity and Contrast Test (FrACT). FrACT testing was undertaken at 4m (avoiding limitations of pixel-size), using 36 trials (avoiding fatigue). Best corrected VA was significantly better than the initial habitual acuity in both groups, but adults with ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983808 Wed, 15 Jun 2011 23:00:00 +0100 4983808 http://www.medworm.com/index.php?rid=4983807&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704059%26dopt%3DAbstract Authors: Rhodes G, Jeffery L, Evangelista E, Ewing L, Peters M, Taylor L Perceptual adaptation not only produces striking perceptual aftereffects, but also enhances coding efficiency and discrimination by calibrating coding mechanisms to prevailing inputs. Attention to simple stimuli increases adaptation, potentially enhancing its functional benefits. Here we show that attention also increases adaptation to faces. In Experiment 1, face identity aftereffects increased when attention to adapting faces was increased using a change detection task. In Experiment 2, figural (distortion) face aftereffects increased when attention was increased using a snap game (detecting immediate repeats) during adaptation. Both were large effects. Contributions of low-level adaptation were reduced using fr... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983807 Wed, 15 Jun 2011 23:00:00 +0100 4983807 http://www.medworm.com/index.php?rid=4983806&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704060%26dopt%3DAbstract We examined whether different contexts with similar directional changes (straight vs. reversed motion) influence the kappa effect in four experiments. The object's motion appeared to depict only forces under the natural laws of physics on a slope (Experiment 1) or on a horizontal plane (Experiment 2) in virtual 3D space. In Experiments 3 and 4, the motion appeared to be subjected to external or self-driving forces additionally influenced by internal forces on a slope (Experiment 3) or a horizontal plane (Experiment 4). The results demonstrated that the directional effect on the kappa effect was observed only in Experiment 1, and not in Experiments 2 and 3, while the kappa effect was preserved. Furthermore, not even the kappa effect was observed in the reversed motion of Experiment 4. The r... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983806 Wed, 15 Jun 2011 23:00:00 +0100 4983806 http://www.medworm.com/index.php?rid=4983805&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21704061%26dopt%3DAbstract In this study, we measured gaze behavior during curve driving, with the general hypothesis that gaze is not static, when exposed to a global optical flow due to self-motion. In order to study spatio-temporal aspects of gaze during curve driving, we used a driving simulator coupled to a gaze recording system. Ten participants drove seven runs on a track composed of eight curves of various radii (50, 100, 200 and 500m), with each radius appearing in both right and left directions. Results showed that average gaze position was, as previously described, located in the vicinity of the tangent point. However, analysis also revealed the presence of a systematic optokinetic nystagmus (OKN) around the tangent point position. The OKN slow phase direction does not match the local optic flow direction... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983805 Wed, 15 Jun 2011 23:00:00 +0100 4983805 http://www.medworm.com/index.php?rid=4983860&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21684303%26dopt%3DAbstract Authors: O'Hare L, Hibbard PB Images created from noise filtered to have an approximately 1/f amplitude spectrum were altered by adding excess energy concentrated at various spatial frequencies. The effects of this manipulation on judgements of visual discomfort were studied. Visual noise with a 1/f amplitude spectrum (typical of natural images) was judged more comfortable than any image with a relative increase in contrast energy within a narrow spatial frequency band. A peak centred on 0.375-1.5cycles/degree of spatial frequency was consistently judged as more uncomfortable than a peak at a higher spatial frequency. This finding was robust to slight differences in eccentricity, and when stimuli were matched for perceived contrast across spatial frequency. These findings are consisten... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983860 Sun, 12 Jun 2011 23:00:00 +0100 4983860 http://www.medworm.com/index.php?rid=4983837&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21689673%26dopt%3DAbstract Authors: Xu JP, He ZJ, Ooi TL A push-pull training protocol is applied to reduce sensory eye dominance in the foveal region. The training protocol consists of cueing the weak eye to force it to become dominant while the strong eye is suppressed when a pair of dichoptic orthogonal grating stimulus is subsequently presented to it (Ooi & He, 1999). We trained with four pairs of dichoptic orthogonal gratings (0°/90°, 90°/0°, 45°/135° and 135°/45° at 3cpd) to affect the interocular inhibitory interaction tuned to the four trained orientations (0°, 45°, 90° and 135°). After a 10-day training session, we found a significant learning effect (reduced sensory eye dominance) at the trained orientations as well as at two other untrained orientations (22.5° and 67.5°). This sugges... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983837 Sun, 12 Jun 2011 23:00:00 +0100 4983837 http://www.medworm.com/index.php?rid=4983873&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21683730%26dopt%3DAbstract Authors: Calvo MG, Nummenmaa L Saccadic and manual responses were used to investigate the speed of discrimination between happy and non-happy facial expressions in two-alternative-forced-choice tasks. The minimum latencies of correct saccadic responses indicated that the earliest time point at which discrimination occurred ranged between 200 and 280ms, depending on type of expression. Corresponding minimum latencies for manual responses ranged between 440 and 500ms. For both response modalities, visual saliency of the mouth region was a critical factor in facilitating discrimination: The more salient the mouth was in happy face targets in comparison with non-happy distracters, the faster discrimination was. Global image characteristics (e.g., luminance) and semantic factors (i.e., cate... Vision Research journals http://www.medworm.com/rss/comments.php?id=4983873 Sat, 11 Jun 2011 23:00:00 +0100 4983873 http://www.medworm.com/index.php?rid=4928993&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664919%26dopt%3DAbstract Authors: Vincent BT What is the mechanism underlying search phenomena such as search asymmetry? Two-stage models such as Feature Integration Theory and Guided Search propose parallel pre-attentive processing followed by serial post-attentive processing. They claim search asymmetry effects are indicative of finding pairs of features, one processed in parallel, the other in serial. An alternative proposal is that a 1-stage parallel process is responsible, and search asymmetries occur when one stimulus has greater internal uncertainty associated with it than another. While the latter account is simpler, only a few studies have set out to empirically test its quantitative predictions, and many researchers still subscribe to the 2-stage account. This paper examines three separate parallel m... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928993 Wed, 08 Jun 2011 23:00:00 +0100 4928993 http://www.medworm.com/index.php?rid=4928992&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664920%26dopt%3DAbstract Authors: Hautala J, Hyönä J, Aro M In previous eye movement research on word length effects, spatial width has been confounded with the number of letters. McDonald (2006) unconfounded these factors by rendering all words in sentences in constant spatial width. In the present study, the Arial font with proportional letter spacing was used for varying the number of letters while equating for spatial width, while the Courier font with monospaced letter spacing was used to measure the contribution of spatial width to the observed word length effect. Number of letters in words affected single fixation duration on target words, whereas words' spatial width determined fixation locations in words and the probability of skipping a word. The results support the existence of distinct subsystems... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928992 Wed, 08 Jun 2011 23:00:00 +0100 4928992 http://www.medworm.com/index.php?rid=4928994&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21663755%26dopt%3DAbstract Authors: Hartwig A, Gowen E, Neil Charman W, Radhakrishnan H The aim of the study was to compare head posture in young, adult emmetropes and corrected myopes during a reading task. Thirty-two (32) myopes (mean spherical equivalent: -3.46±2.35D) and 22 emmetropes (mean spherical equivalent: -0.03±0.36D) participated in the study. Of the myopes, 16 were progressing (rate of progression ⩾-0.5D over the previous 2years), 12 were stable (changes of -0.25D or less over 2years) and four could not be classified. Seated subjects were asked to read a text binocularly in their habitual posture. To measure head posture, two simultaneous images were recorded from different directions. In a separate study with the same subjects and conditions, a motion monitor was used to track head posture for ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928994 Tue, 31 May 2011 23:00:00 +0100 4928994 http://www.medworm.com/index.php?rid=4928998&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21640747%26dopt%3DAbstract Authors: To MP, Gilchrist ID, Troscianko T, Tolhurst DJ We conducted suprathreshold discrimination experiments to compare how natural-scene information is processed in central and peripheral vision (16° eccentricity). Observers' ratings of the perceived magnitude of changes in naturalistic scenes were lower for peripheral than for foveal viewing, and peripheral orientation changes were rated less than peripheral colour changes. A V1-based Visual Difference Predictor model of the magnitudes of perceived foveal change was adapted to match the sinusoidal grating sensitivities of peripheral vision, but it could not explain why the ratings for changes in peripheral stimuli were so reduced. Perceived magnitude ratings for peripheral stimuli were further reduced by simultaneous presentation ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928998 Thu, 26 May 2011 23:00:00 +0100 4928998 http://www.medworm.com/index.php?rid=4928997&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21651926%26dopt%3DAbstract Authors: Tsirlin I, Wilcox LM, Allison RS Monocular occlusions have been shown to play an important role in stereopsis. Among other contributions to binocular depth perception, monocular occlusions can create percepts of illusory occluding surfaces. It has been argued that the precise location in depth of these illusory occluders is based on the constraints imposed by occlusion geometry. Tsirlin et al. (2010) proposed that when these constraints are weak, the depth of the illusory occluder can be biased by a neighboring disparity-defined feature. In the present work we test this hypothesis using a variety of stimuli. We show that when monocular occlusions provide only partial constraints on the magnitude of depth of the illusory occluders, the perceived depth of the occluders can be bi... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928997 Thu, 26 May 2011 23:00:00 +0100 4928997 http://www.medworm.com/index.php?rid=4928996&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21658403%26dopt%3DAbstract Authors: Xu JP, He ZJ, Ooi TL Perceptual learning is an important means for the brain to maintain its agility in a dynamic environment. Top-down focal attention, which selects task-relevant stimuli against competing ones in the background, is known to control and select what is learned in adults. Still unknown, is whether the adult brain is able to learn highly visible information beyond the focus of top-down attention. If it is, we should be able to reveal a purely stimulus-driven perceptual learning occurring in functions that are largely determined by the early cortical level, where top-down attention modulation is weak. Such an automatic, stimulus-driven learning mechanism is commonly assumed to operate only in the juvenile brain. We performed perceptual training to reduce sensory ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928996 Thu, 26 May 2011 23:00:00 +0100 4928996 http://www.medworm.com/index.php?rid=4928999&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21640746%26dopt%3DAbstract Authors: Harris WF Pascal's ring is a hexagon each of whose corners represents one of the six cardinal points of an optical system and whose sides represent relationships of relative axial position of the cardinal points. Changes to the ring represent the axial displacements of the cardinal points of the visual optical system of an eye that are caused when a spectacle lens compensates for the ametropia. Pascal's schema was described some 70years ago with little theoretical justification. The purpose of this paper is to derive expressions for the axial locations of the cardinal points of a compound system consisting of an optical instrument and a visual optical system and for the shift caused by the instrument, and to provide theoretical justification for Pascal's schema. The cardinal p... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928999 Mon, 23 May 2011 23:00:00 +0100 4928999 http://www.medworm.com/index.php?rid=4928995&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21658404%26dopt%3DAbstract Authors: Augusteyn RC, Mohamed A, Nankivil D, Veerendranath P, Arrieta E, Taneja M, Manns F, Ho A, Parel JM The purpose of this study was to study the age-dependence of the optomechanical properties of human lenses during simulated disaccommodation in a mechanical lens stretcher, designed to determine accommodative forces as a function of stretch distance, to compare the results with in vivo disaccommodation and to examine whether differences exist between eyes harvested in the USA and India. Postmortem human eyes obtained in the USA (n=46, age=6-83years) and India (n=91, age=1day-85years) were mounted in an optomechanical lens stretching system and dissected to expose the lens complete with its accommodating framework, including zonules, ciliary body, anterior vitreous and a segmented... Vision Research journals http://www.medworm.com/rss/comments.php?id=4928995 Mon, 23 May 2011 23:00:00 +0100 4928995 http://www.medworm.com/index.php?rid=4885061&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21624383%26dopt%3DAbstract Authors: Olk B, Garay-Vado AM Attention may be biased towards faces but a face advantage may be linked to the upright orientation of a face. Three experiments, employing a flanker and a cuing paradigm, investigated effects of face orientation, perceptual load and allocation of attention. Experiment 1 demonstrated that, irrespective of load, attention is biased towards upright face distractors while inverted face distractors are easy to ignore. Experiment 2 verified that inverted face distractors can interfere provided that they are attended to volitionally, likely because the volitional allocation of attention promotes face processing and gender classification (Experiment 3). PMID: 21624383 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=4885061 Sun, 22 May 2011 23:00:00 +0100 4885061 http://www.medworm.com/index.php?rid=4885062&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21609729%26dopt%3DAbstract Authors: Yi F, Robert Iskander D, Collins M It is known that the depth of focus (DOF) of the human eye can be affected by the higher order aberrations. We estimated the optimal combinations of primary and secondary Zernike spherical aberration to expand the DOF and evaluated their efficiency in real eyes using an adaptive optics system. The ratio between increased DOF and loss of visual acuity was used as the performance indicator. The results indicate that primary or secondary spherical aberration alone shows similar effectiveness in extending the DOF. However, combinations of primary and secondary spherical aberration with different signs provide better efficiency for expanding the DOF. This finding suggests that the optimal combinations of primary and secondary spherical aberration ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4885062 Mon, 16 May 2011 23:00:00 +0100 4885062 http://www.medworm.com/index.php?rid=4885064&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21605587%26dopt%3DAbstract Authors: Popova E, Kupenova P The effect of dopamine D(1) receptor blockade by SCH 23390 on the V-logI function of the ERG b- and d-waves was investigated in dark and light adapted frog eyes. We obtained that the blocker enhanced the amplitude of the b- and d-waves in both conditions of adaptation. The enhancing effect of the blocker was more pronounced on the rod- than cone-dominated responses for the both ERG waves. The absolute sensitivity of the b-wave was not altered, but that of the d-wave was significantly increased. The intensity-response function of the b-wave, but not that of the d-wave, was shifted to the left along the intensity axis. The b-wave V-logI function had steeper slope and narrower dynamic range in both dark and light adapted eyes after the D(1) receptor blockade.... Vision Research journals http://www.medworm.com/rss/comments.php?id=4885064 Fri, 13 May 2011 23:00:00 +0100 4885064 http://www.medworm.com/index.php?rid=4885063&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21605588%26dopt%3DAbstract Authors: Rhys Davies J, Freeman TC Simultaneously adapting to retinal motion and non-collinear pursuit eye movement produces a motion aftereffect (MAE) that moves in a different direction to either of the individual adapting motions. Mack, Hill and Kahn (1989, Perception, 18, 649-655) suggested that the MAE was determined by the perceived motion experienced during adaptation. We tested the perceived-motion hypothesis by having observers report perceived direction during simultaneous adaptation. For both central and peripheral retinal motion adaptation, perceived direction did not predict the direction of subsequent MAE. To explain the findings we propose that the MAE is based on the vector sum of two components, one corresponding to a retinal MAE opposite to the adapting retinal motion... Vision Research journals http://www.medworm.com/rss/comments.php?id=4885063 Fri, 13 May 2011 23:00:00 +0100 4885063 http://www.medworm.com/index.php?rid=4885065&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21601590%26dopt%3DAbstract Authors: Khan MI, Barlow RB, Weinstock RS The goal of this pilot study was to assess the effects of acute hypoglycemia on retinal function and contrast sensitivity in individuals with and without diabetes. Hyperinsulinemic hypoglycemic and euglycemic clamp procedures were performed in subjects without diabetes (n=7) and with controlled type 1 diabetes (n=5). Mean age was 28years, and none had retinal disease. During euglycemia (glucose 95-110mg/dl) and acute hypoglycemia (glucose 50-55mg/dl), contrast sensitivity was measured and spatial retinal responses were recorded with multifocal electroretinograms (mfERG), a rapid technique for mapping sensitivity from the foveal, macular and peripheral areas of the retina. During hypoglycemia, retinal responses (mfERG P1 wave) were decreased in ... Vision Research journals http://www.medworm.com/rss/comments.php?id=4885065 Wed, 11 May 2011 23:00:00 +0100 4885065 http://www.medworm.com/index.php?rid=4885066&cid=s_35430_30_f&fid=35430&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21596053%26dopt%3DAbstract Authors: Williams DR A quarter century ago, we were limited to a macroscopic view of the retina inside the living eye. Since then, new imaging technologies, including confocal scanning laser ophthalmoscopy, optical coherence tomography, and adaptive optics fundus imaging, transformed the eye into a microscope in which individual cells can now be resolved noninvasively. These technologies have enabled a wide range of studies of the retina that were previously impossible. PMID: 21596053 [PubMed - as supplied by publisher] (Source: Vision Research) Vision Research journals http://www.medworm.com/rss/comments.php?id=4885066 Mon, 09 May 2011 23:00:00 +0100 4885066