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Vision Research

Fakhri Shafai, Ipek Oruc
The other-race effect is the finding of diminished performance in recognition of other-race faces compared to those of own-race. It has been suggested that the other-race effect stems from specialized expert processes being tuned exclusively to own-race faces. In the present study, we measured recognition contrast thresholds for own- and other-race faces as well as houses for Caucasian observers. We have factored face recognition performance into two invariant aspects of visual function: efficiency, which is related to neural computations and processing demanded by the task, and equivalent input noise, related to signal degradation within the visual system...
December 30, 2017: Vision Research
Morgan E McIntyre, Derek H Arnold
When a moving surface alternates in colour and direction, perceptual couplings of colour and motion can differ from their physical correspondence. Periods of motion tend to be perceptually bound with physically delayed colours - a colour / motion perceptual asynchrony. This can be eliminated by motion transparency. Here we show that the colour / motion perceptual asynchrony is not invariably eliminated by motion transparency. Nor is it an inevitable consequence given a particular physical input. Instead, it can emerge when moving surfaces are perceived as alternating in direction, even if those surfaces seem transparent, and it is eliminated when surfaces are perceived as moving invariably...
December 28, 2017: Vision Research
Martin Rolfs, Nicholas Murray-Smith, Marisa Carrasco
Traditional perceptual learning protocols rely almost exclusively on long periods of uninterrupted fixation. Taking a first step towards understanding perceptual learning in natural vision, we had observers report the orientation of a briefly flashed stimulus (clockwise or counterclockwise from a reference orientation) presented strictly during saccade preparation at a location offset from the saccade target. For each observer, the saccade direction, stimulus location, and orientation remained the same throughout training...
December 22, 2017: Vision Research
Alexander Leube, Stephanie Kostial, Guy Alex Ochakovski, Arne Ohlendorf, Siegfried Wahl
The purpose of the study was to investigate the sign-dependent response to real and simulated spherical defocus on the visual acuity under monochromatic light conditions. The investigation included 15 myopic participants with a mean spherical equivalent error of -2.98 ± 2.17 D. Visual acuity (VA) was tested with and without spherical defocus using the source method (simulated defocus) and the observer method (lens-induced defocus) in a range of ± 3.0 D in 1.0 D steps. VA was assessed using Landolt Ćs, while the threshold was determined with an adaptive staircase procedure...
December 22, 2017: Vision Research
Isabelle Bülthoff, Betty J Mohler, Ian M Thornton
Viewing faces in motion or attached to a body instead of isolated static faces improves their subsequent recognition. Here we enhanced the ecological validity of face encoding by having observers physically moving in a virtual room populated by life-size avatars. We compared the recognition performance of this active group to two control groups. The first control group watched a passive reenactment of the visual experience of the active group. The second control group saw static screenshots of the avatars. All groups performed the same old/new recognition task after learning...
December 21, 2017: Vision Research
Jessica Galliussi, Lukasz Grzeczkowski, Walter Gerbino, Michael H Herzog, Paolo Bernardis
Perceptual learning can occur for a feature irrelevant to the training task, when it is sub-threshold and outside of the focus of attention (task-irrelevant perceptual learning, TIPL); however, TIPL does not occur when the task-irrelevant feature is supra-threshold. Here, we asked the question whether TIPL occurs when the task-irrelevant feature is sub-threshold but within the focus of spatial attention. We tested participants in three different discrimination tasks performed on a 3-dot stimulus: a horizontal Vernier task and a vertical bisection task (during pre- and post-training sessions), and a luminance task (during training)...
December 20, 2017: Vision Research
Olga A Korolkova
Recent studies suggest that video recordings of human facial expressions are perceived differently than linear morphing between the first and last frames of these records. Also, observers can differentiate dynamic expressions presented in normal versus time-reversed frame orders. To date, the simultaneous influence of dynamics (natural or linear) and timeline (normal or reversed) has not yet been tested on a wide range of dynamic emotional expressions and the transitions between them. We compared the perception of dynamic transitions between basic emotions in realistic (human-posed) and artificial (linearly morphed) stimuli which were presented in reversed or non-reversed order...
December 20, 2017: Vision Research
Wei-Lun Chou, Su-Ling Yeh
Encoding predictive information and allocating visual attention according to the probability distribution is one of the marvelous achievements of our visual system. Unlike previous studies on object-based attention in which the validity of location-based cues and that of object-based cues covaried, we differentiate the two and examine whether our visual system can calculate the usefulness of the cue based on, separately and independently, the probability distribution of location on one hand and object that contains multiple locations on the other...
December 19, 2017: Vision Research
Tobias Moehler, Katja Fiehler
Previous research on the spatiotemporal dynamics of exogenous and endogenous attentional allocation during saccade preparation yielded conflicting results. We hypothesize that this can be explained by the cueing type used to orient attention in a perceptual task. We investigated the time-course of attentional allocation as a function of cueing type (central vs peripheral), spatial congruency of the cued perceptual and saccade task locations, and cue validity in a dual-task paradigm. Participants performed a visual discrimination task during saccade preparation...
December 17, 2017: Vision Research
Xin-Yu Xie, Cong Yu
Location specific perceptual learning can transfer to a new location if the new location is trained with a secondary task that by itself does not impact the performance of the primary learning task (double training). Learning may also transfer to other locations when double training is performed at the same location. Here we investigated the mechanisms underlying double-training enabled learning and transfer with an external noise paradigm. Specifically, we measured the Vernier thresholds at various external noise contrasts before and after double training...
December 17, 2017: Vision Research
Gabriel Arnold, Malika Auvray
Sensory substitution devices aim at assisting a deficient sensory modality by means of another sensory modality. For instance, to perceive with visual-to-tactile devices, users learn to recognize visual stimuli through their tactile conversion. A crucial characteristic of learning lies in the ability to generalize, that is, the ability to extend the acquired perceptual abilities to both new stimuli and new perceptual conditions. The study reported here investigated the perceptual learning of tactile alphanumerical stimuli...
December 16, 2017: Vision Research
Zijiang J He, Teng Leng Ooi, Yong R Su
The visual system can represent a partially occluded 3-D surface from images of separated surface segments. The underlying amodal surface integration process accomplishes this by amodally extending each surface segment behind the occluder (amodal surface extension) and integrating the extended surfaces to form a whole surface representation. We conducted five experiments to investigate how depth cues, such as binocular disparity, half-occlusion, and monocular depth cues (T-junctions and L-junctions), contribute to amodal surface extension, and how the geometrical relationship and image similarity among the surface segments affects surface integration...
December 14, 2017: Vision Research
Baingio Pinna, Adam Reeves, Jan Koenderink, Andrea van Doorn, Katia Deiana
The problem of perceptual organization was studied by Gestalt psychologists in terms of figure-ground segregation. In this paper we explore a new principle of figure-ground segregation: accentuation. We demonstrate the effectiveness of accentuation relative to other Gestalt principles, and also considSubmitted to Vision ResearchSubmitted to Vision Researcher it autonomous as it can agree with or oppose them. We consider three dynamic aspects of the principle, namely: attraction, accentuation and assignment...
December 12, 2017: Vision Research
Maryam Ahmadi, Elizabeth A McDevitt, Michael A Silver, Sara C Mednick
Studies of visual cortical responses following visual perceptual learning (VPL) have produced diverse results, revealing neural changes in early and/or higher-level visual cortex as well as changes in regions responsible for higher cognitive processes such as attentional control. In this study, we investigated substrates of VPL in the human brain by recording visual evoked potentials with high-density electroencephalography (hdEEG) before (Session 1) and after (Session 2) training on a texture discrimination task (TDT), with two full nights of sleep between sessions...
December 7, 2017: Vision Research
Matthew Heath, Francisco L Colino, Jillian Chan, Olave E Krigolson
The visuomotor mental rotation (VMR) of a saccade requires a response to a region of space that is dissociated from a stimulus by a pre-specified angle, and work has shown a monotonic increase in reaction times as a function of increasing oblique angles of rotation. These results have been taken as evidence of a continuous process of rotation and have generated competing hypotheses. One hypothesis asserts that rotation is mediated via frontoparietal structures, whereas a second states that a continuous shift in the activity of direction-specific neurons in the superior colliculus (SC) supports rotation...
December 7, 2017: Vision Research
Charlotte J W Connell, Benjamin Thompson, Hayden Green, Rachel K Sullivan, Nicholas Gant
This study investigated the influence of five days of moderate intensity aerobic exercise on the acquisition and consolidation of visual perceptual learning using a motion direction discrimination (MDD) task. The timing of exercise relative to learning was manipulated by administering exercise either before or after perceptual training. Within a matched-subjects design, twenty-seven healthy participants (n = 9 per group) completed five consecutive days of perceptual training on a MDD task under one of three interventions: no exercise, exercise before the MDD task, or exercise after the MDD task...
December 2, 2017: Vision Research
Diako Mardanbegi, Rebecca Killick, Baiqiang Xia, Thomas Wilcockson, Hans Gellersen, Peter Sawyer, Trevor J Crawford
Recent research have shown that the eye movement data measured by an eye tracker does not necessarily reflect the exact rotations of the eyeball. For example, post-saccadic eye movements may be more reflecting the relative movements between the pupil and the iris rather than the eyeball oscillations. Since, accurate measurement of eye movements is important in many studies, it is crucial to identify different factors that influence the dynamics of the eye movements measured by an eye tracker. Previous studies have shown that deformation of the internal structure of the iris and size of the pupil directly affect the amplitude of the post-saccadic oscillations that are measured by video-based eye trackers that are pupil-based...
November 29, 2017: Vision Research
Emma E M Stewart, Alexander C Schütz
With every saccade, humans must reconcile the low resolution peripheral information available before a saccade, with the high resolution foveal information acquired after the saccade. While research has shown that we are able to integrate peripheral and foveal vision in a near-optimal manner, it is still unclear which mechanisms may underpin this important perceptual process. One potential mechanism that may moderate this integration process is visual attention. Pre-saccadic attention is a well documented phenomenon, whereby visual attention shifts to the location of an upcoming saccade before the saccade is executed...
November 25, 2017: Vision Research
Gesa Lange, Peter De Weerd
Substantial transfer of perceptual skill learning can be achieved across large distances in the visual field by a brief pre-test, training-plus-exposure, or a double-training paradigm (Current Biology 18 (2008) 1922-1926; Vision Research 50 (2010) 368-374; The Journal of Neuroscience 30 (2010) 12323-12328). Additionally, subliminal exposure has been shown to be beneficial for subsequent perceptual learning. Here, we tested the generalization of orientation discrimination learning from a fully trained location towards four other test locations, either in the same or opposite hemifield as the training location, which each were subjected to a different type of pre-conditioning...
November 24, 2017: Vision Research
Madhumitha S Mahadevan, Harold E Bedell, Scott B Stevenson
Visual spatial attention has been shown to influence both contrast detection and suprathreshold contrast perception, as well as manual and saccadic reaction times (SRTs). Because SRTs are influenced also by stimulus contrast, we investigated if the enhancement of perceived contrast that accompanies attention could account for the shorter SRTs observed for attended targets locations. We conducted two dual-task experiments to assess psychophysical and oculomotor responses to non-foveal targets of various contrast for different spatial-attention-cueing conditions...
November 24, 2017: Vision Research
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