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Vision Research

Derek H Arnold, Kirstie Petrie, Alan Johnston
Visual analyses of movement are disproportionately reliant on luminance contrast, as opposed to colour differences. One consequence is that if a moving pattern is defined solely by changes in colour (is equiluminant), people can report having no sensation of movement, despite still being able to 'see' the pattern. This is called motion standstill. To date there have been no formal reports of foveal motion standstill. Here we investigate whether this is because the conditions necessary for inducing motion standstill are particular to peripheral vision and therefore absent at the fovea...
March 23, 2017: Vision Research
J M Bosten, P T Goodbourn, G Bargary, R J Verhallen, A J Lawrance-Owen, R E Hogg, J D Mollon
A factor analysis was performed on 25 visual and auditory performance measures from 1060 participants. The results revealed evidence both for a factor relating to general perceptual performance, and for eight independent factors that relate to particular perceptual skills. In an unrotated PCA, the general factor for perceptual performance accounted for 19.9% of the total variance in the 25 performance measures. Following varimax rotation, 8 consistent factors were identified, which appear to relate to (1) sensitivity to medium and high spatial frequencies, (2) auditory perceptual ability (3) oculomotor speed, (4) oculomotor control, (5) contrast sensitivity at low spatial frequencies, (6) stereo acuity, (7) letter recognition, and (8) flicker sensitivity...
March 16, 2017: Vision Research
Judith Schomaker, Daniel Walper, Bianca C Wittmann, Wolfgang Einhäuser
In addition to low-level stimulus characteristics and current goals, our previous experience with stimuli can also guide attentional deployment. It remains unclear, however, if such effects act independently or whether they interact in guiding attention. In the current study, we presented natural scenes including every-day objects that differed in affective-motivational impact. In the first free-viewing experiment, we presented visually-matched triads of scenes in which one critical object was replaced that varied mainly in terms of motivational value, but also in terms of valence and arousal, as confirmed by ratings by a large set of observers...
March 14, 2017: Vision Research
Frank A Boutsen, Justin D Dvorak, Vinay K Pulusu, Elliott D Ross
Depending on a subject's attentional bias, robust changes in emotional perception occur when facial blends (different emotions expressed on upper/lower face) are presented tachistoscopically. If no instructions are given, subjects overwhelmingly identify the lower facial expression when blends are presented to either visual field. If asked to attend to the upper face, subjects overwhelmingly identify the upper facial expression in the left visual field but remain slightly biased to the lower facial expression in the right visual field...
March 13, 2017: Vision Research
Abinaya Priya Venkataraman, Peter Lewis, Peter Unsbo, Linda Lundström
Optimal temporal modulation of the stimulus can improve foveal contrast sensitivity. This study evaluates the characteristics of the peripheral spatiotemporal contrast sensitivity function in normal-sighted subjects. The purpose is to identify a temporal modulation that can potentially improve the remaining peripheral visual function in subjects with central visual field loss. High contrast resolution cut-off for grating stimuli with four temporal frequencies (0, 5, 10 and 15Hz drift) was first evaluated in the 10° nasal visual field...
March 13, 2017: Vision Research
Christoph Redies, Anselm Brachmann, Johan Wagemans
We asked whether "good composition" or "visual rightness" of artworks manifest themselves in a particular arrangement of basic image features, such as oriented luminance edges. Specifically, we analysed the layout of edge orientations in images from a collection of >1600 paintings of Western provenance by comparing pairwise the orientation of each edge in an image with the orientations of all other edges in the same image. From the resulting orientation histograms, we calculated Shannon entropy and parallelism (i...
March 10, 2017: Vision Research
Wolfgang Einhäuser, Philipp Methfessel, Alexandra Bendixen
When distinct stimuli are presented to the two eyes, their mental representations alternate in awareness. Here, such "binocular rivalry" was used to investigate whether audio-visual associations bias visual perception. To induce two arbitrary associations, each between a tone and a grating of a specific color and motion direction, observers were required to respond whenever this combination was presented, but not for other tone-grating combinations. After about 20min of this induction phase, each of the gratings was presented to one eye to induce rivalry, while either of the two tones or no tone was played...
March 6, 2017: Vision Research
Lisa Hamm, Zidong Chen, Jinrong Li, Joanna Black, Shuan Dai, Junpeng Yuan, Minbin Yu, Benjamin Thompson
In patients with anisometropic or strabismic amblyopia, interocular suppression can be minimized by presenting high contrast stimulus elements to the amblyopic eye and lower contrast elements to the fellow eye. This suggests a structurally intact binocular visual system that is functionally suppressed. We investigated whether suppression can also be overcome by contrast balancing in children with deprivation amblyopia due to childhood cataracts. To quantify interocular contrast balance, contrast interference thresholds were measured using an established dichoptic global motion technique for 21 children with deprivation amblyopia, 14 with anisometropic or mixed strabismic/anisometropic amblyopia and 10 visually normal children (mean age mean=9...
March 5, 2017: Vision Research
Xue Dong, Jianying Bai, Min Bao
A new illusion is described. Randomly positioned dots moved radially within an imaginary annular window. The dots' motion periodically changed the direction, leading to an alternating percept of expanding and contracting motion. Strikingly, the apparent size of the enclosed circular region shrank during the dots' expanding phases and dilated during the contracting phases. We quantitatively measured the illusion, and found that the presence of energy at the local kinetic edge could not account for the illusion...
February 27, 2017: Vision Research
Brian D Krawitz, Shelley Mo, Lawrence S Geyman, Steven A Agemy, Nicole K Scripsema, Patricia M Garcia, Toco Y P Chui, Richard B Rosen
Given the complexity of the current system used to stage diabetic retinopathy (DR) and the risks and limitations associated with intravenous fluorescein angiography (IVFA), noninvasive quantification of DR severity is desirable. We examined the utility of acircularity index and axis ratio of the foveal avascular zone (FAZ), metrics that can noninvasively quantify the severity of diabetic retinopathy without the need for axial length to correct for individual retinal magnification. A retrospective review was performed of type 2 diabetics and age-matched controls imaged with optical coherence tomography angiography (OCTA)...
February 26, 2017: Vision Research
Nathalie Guyader, Alan Chauvin, Muriel Boucart, Carole Peyrin
The visual perception of human faces by man is fast and efficient compared to that of other categories of objects. Using a saccadic choice task, recent studies showed that participants were able to initiate fast reliable saccades in just 100-110ms toward an image of a human face, when this was presented alongside another image without a face. This extremely fast saccadic reaction time is barely predicted using classical models of visual perception. Thus, the present research investigates whether this result might be explained by the low spatial frequency content of images...
February 26, 2017: Vision Research
Dylan Rose, Peter Bex
Individuals with pathological or simulated central visual field loss can be trained to use a preferred retinal locus (PRL) as a substitute for their non-functioning fovea. The functional benefits of a stable PRL are well documented, but little is known about oculomotor adaptations during PRL acquisition or transfer of training to another location in response to real or simulated disease progression. In this study, eight normally-sighted observers were trained to use a pseudo-PRL (pPRL) at one of two locations by guiding an eccentrically placed, gaze-contingent ring over a fixation target...
February 25, 2017: Vision Research
Min-Suk Kang, Sori Kim, Kyoung-Min Lee
We often shift our eyes to an interesting stimulus, but it is important to inhibit that eye movement in some environments (e.g., a no-look pass in basketball). Here, we investigated participants' ability to inhibit eye movements when they had to process a peripheral target with a requirement to maintain strict fixation. An array of eight letters composed of four characters was briefly presented and a directional cue was centrally presented to indicate the target location. The stimulus onset asynchrony (SOA) between the cue and the stimulus array was chosen from six values, consisting of pre-cue conditions (-400 and -200ms), a simultaneous cue condition (0ms), and post-cue conditions (200, 400, and 800ms)...
February 17, 2017: Vision Research
Mika Koivisto, Ella Kahila
Top-down processes are widely assumed to be essential in visual awareness, subjective experience of seeing. However, previous studies have not tried to separate directly the roles of different types of top-down influences in visual awareness. We studied the effects of top-down preparation and object substitution masking (OSM) on visual awareness during categorization of objects presented in natural scene backgrounds. The results showed that preparation facilitated categorization but did not influence visual awareness...
February 17, 2017: Vision Research
Alain Jacot-Guillarmod, Yunjiao Wang, Claudia Pedroza, Haluk Ogmen, Zachary Kilpatrick, Krešimir Josić
Levelt's Propositions are central to understanding a wide range of multistable perceptual phenomena, but it is unclear whether they extend to perceptual multistability involving interocular grouping. We presented split-grating stimuli with complementary halves of the same color (either red or green) to human subjects. The subjects reported four percepts in alternation: the two stimuli presented to each eye (half red and half green), as well as the two single color (all red or all green), interocularly grouped percepts...
February 17, 2017: Vision Research
Susann Meyberg, Petra Sinn, Ralf Engbert, Werner Sommer
Microsaccades - i.e., small fixational saccades generated in the superior colliculus (SC) - have been linked to spatial attention. While maintaining fixation, voluntary shifts of covert attention toward peripheral targets result in a sequence of attention-aligned and attention-opposing microsaccades. In most previous studies the direction of the voluntary shift is signaled by a spatial cue (e.g., a leftwards pointing arrow) that presents the most informative part of the cue (e.g., the arrowhead) in the to-be attended visual field...
February 17, 2017: Vision Research
Stephen Jachim, Emma Gowen, Paul A Warren
Collinear facilitation refers to the increase in sensitivity found for a target when aligned between nearby, brighter flankers. Many studies have explored the spatial and temporal aspects of this arrangement, and there is a consensus that two mechanisms could be responsible for this phenomenon; lateral excitation within V1 and extra-striate feedback to V1. There is some debate as to whether facilitation can still occur if the target is presented before the flankers, a manipulation known as backward masking, which could rely on feedback to V1...
February 17, 2017: Vision Research
Tara L Alvarez, Eun H Kim, Chang Yaramothu, Bérangère Granger-Donetti
A paucity of research exists to investigate whether the normal aging process influences the ability to adapt disparity vergence and phoria. Vergence eye movements and dissociated phoria were recorded from 49 healthy subjects (ages 20-70years) using an objective eye movement tracking system. Four-degree vergence responses were modified using a double-step protocol. Dynamics of vergence were quantified via peak velocity. The phoria adaptation experiment measured the magnitude (net change in phoria level) and rate (magnitude divided by the time constant) of phoria adaption during 5min of sustained fixation on a binocular target (40cm/8...
February 16, 2017: Vision Research
Chengwen Luo, Edwin Burns, Hong Xu
Prolonged exposure to a happy face makes subsequently presented faces appear sadder: the facial emotion aftereffect (FEA). People with autism spectrum disorders and their relatives have diminished holistic perception of faces. Levels of autism can be measured continuously in the general population by autistic traits using the autism-quotient (AQ). Prior work has not found any association between AQ and FEA in adults, possibly due to non-holistic processing strategies employed by those at the higher end of the spectrum...
February 16, 2017: Vision Research
Francesca Pei, Stefano Baldassi, Jeffrey J Tsai, Holly E Gerhard, Anthony M Norcia
Contrast sensitivity is regulated by neural mechanisms that flexibly adjust responsiveness to optimize stimulus encoding across different environments. Here we studied the developmental status of gain control mechanisms in school-age children (5-17years) and adults using a visual masking paradigm. A variable contrast, spatially random 2-D noise test pattern was masked by the presence of a superimposed independent noise pattern presented at 0, 12 and 40% contrast. Frequency-tagged steady state visual evoked potentials were used to separately record responses to the test (5...
February 16, 2017: Vision Research
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