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Vision Research

Ezequiel M Salido, Leonardo N Servalli, Juan Carlos Gomez, Claudio Verrastro
The amount of available rhodopsin on the photoreceptor outer segment and its change over time is not considered in classic models of phototransduction. Thus, those models do not take into account the absorptance variation of the outer segment under different brightness conditions. The relationship between the light absorbed by a medium and its absorptance is well described by the Beer-Lambert law. This newly proposed model implements the absorptance variation phenomenon in a set of equations that admit photons per second as input and results in active rhodopsins per second as output...
January 13, 2017: Vision Research
Matteo Toscani, Matteo Valsecchi, Karl R Gegenfurtner
Humans are able to estimate the reflective properties of the surface (albedo) of an object despite the large variability in the reflected light due to shading, illumination and specular reflection. Here we first used a physically based rendering simulation to study how different statistics (i.e. percentiles) based on the luminance distributions of matte and glossy objects predict the overall surface albedo. We found that the brightest parts of matte surfaces are good predictors of the surface albedo. As expected, the brightest parts led to poor performance in glossy surfaces...
January 13, 2017: Vision Research
Laurie M Wilcox, Brittney Hartle, Aliya Solski, Kevin J Mackenzie, Deborah Giaschi
We report a series of experiments in which we assess depth discrimination performance in adults and children using a disparity-balanced target configuration to avoid the effects of anticipatory vergence eye movements. In our first study we found that children outperformed adults by a substantial margin, and the adults were consistently near chance. This was surprising given that we initially tested naïve adults to provide a benchmark for the children's data, and all observers met the criterion for stereoacuity...
January 11, 2017: Vision Research
C S Cowan, J Sabharwal, R L Seilheimer, S M Wu
The remarkable dynamic range of vision is facilitated by adaptation of retinal sensitivity to ambient lighting conditions. An important mechanism of sensitivity adaptation is control of the spatial and temporal window over which light is integrated. The retina accomplishes this by switching between parallel synaptic pathways with differing kinetics and degrees of synaptic convergence. However, the relative shifts in spatial and temporal integration are not well understood - particularly in the context of the antagonistic spatial surround...
January 10, 2017: Vision Research
Timothy D Sweeny, David Whitney
A person's gaze reveals much about their focus of attention and intentions. Sensitive perception of gaze is thus highly relevant for social interaction, especially when it is directed toward the viewer. Yet observers also tend to overestimate the likelihood that gaze is directed toward them. How might the visual system balance these competing goals, maximizing sensitivity for discriminating gazes that are relatively direct, while at the same time allowing many gazes to appear as if they look toward the viewer? Perceiving gaze is an emergent visual process that involves integrating information from the eyes with the rotation of the head...
January 10, 2017: Vision Research
Natela Shanidze, Stephen Heinen, Preeti Verghese
Macular degeneration results in heterogeneous central field loss (CFL) and often has asymmetrical effects in the two eyes. As such, it is not clear to what degree the movements of the two eyes are coordinated. To address this issue, we examined smooth pursuit quantitatively in CFL participants during binocular viewing and compared it to the monocular viewing case. We also examined coordination of the two eyes during smooth pursuit and how this coordination was affected by interocular ratios of acuity and contrast, as well as CFL-specific interocular differences, such as scotoma sizes and degree of binocular overlap...
January 9, 2017: Vision Research
Emese Maróti, Balázs Knakker, Zoltán Vidnyánszky, Béla Weiss
External periodic stimuli entrain brain oscillations and affect perception and attention. It has been shown that background music can change oculomotor behavior and facilitate detection of visual objects occurring on the musical beat. However, whether musical beats in different tempi modulate information sampling differently during natural viewing remains to be explored. Here we addressed this question by investigating how listening to naturalistic drum grooves in two different tempi affects eye movements of participants viewing natural scenes on a computer screen...
January 9, 2017: Vision Research
Roeland J Verhallen, Jenny M Bosten, Patrick T Goodbourn, Adam J Lawrance-Owen, Gary Bargary, J D Mollon
The ability to recognize faces varies considerably between individuals, but does performance co-vary for tests of different aspects of face processing? For 397 participants (of whom the majority were university students) we obtained scores on the Mooney Face Test, Glasgow Face Matching Test (GFMT), Cambridge Face Memory Test (CFMT) and Composite Face Test. Overall performance was significantly correlated for each pair of tests, and we suggest the term f for the factor underlying this pattern of positive correlations...
January 7, 2017: Vision Research
Kara J Emery, Vicki J Volbrecht, David H Peterzell, Michael A Webster
A longstanding and unresolved question is how observers construct a discrete set of color categories to partition and label the continuous variations in light spectra, and how these categories might reflect the neural representation of color. We explored the properties of color naming and its relationship to color appearance by analyzing individual differences in color-naming and hue-scaling patterns, using factor analysis of individual differences to identify separate and shared processes underlying hue naming (labeling) and hue scaling (color appearance)...
January 5, 2017: Vision Research
Sarah L Elliott, Kelly Chu, Jill Coleman
This study examined whether category boundaries between Black and White faces relate to individual attitudes about race. Fifty-seven (20 Black, 37 White) participants completed measures of explicit racism, implicit racism, collective self-esteem (CSE), and racial centrality. Category boundaries between Black and White faces were measured in three separate conditions: following adaptation to (1) a neutral gray background, a sequence of (2) Black or (3) White faces. Two additional conditions measured category boundaries for facial distortion to investigate whether attitudes relate to mechanisms of racial identity alone, or to more global mechanisms of face perception...
January 4, 2017: Vision Research
Stephen A Burns, John S Werner, William Merigan, Susana Marcos
No abstract text is available yet for this article.
January 3, 2017: Vision Research
David P M Northmore
Only ray-finned fishes possess a torus longitudinalis (TL), a paired, elongated body attached to the medial margins of the optic tectum. Its granule cells project large numbers of fine fibers running laterally over adjacent tectum, synapsing excitatorily on the spiny dendrites of pyramidal cells. Sustained TL activity is evoked visuotopically by dark stimuli; TL bursting is a corollary discharge of saccadic eye movements. To suggest a function for this ancient structure, neural network models were constructed to show that: (1) pyramidal cells could form an attentional locus, selecting one out of several moving objects to track, but rapid image shifts caused by saccades disrupt tracking; (2) TL could supply both the pre-saccade position of a locus, and the shift predicted from a saccade so as to prime pyramidal dendrites at the target location, ensuring the locus stays with the attended object; (3) that the specific pattern of synaptic connections required for such predictive priming could be learned by an unsupervised rule; (4) temporal and spatial filtering of visual pattern input to TL allows learning from a complex scene...
January 3, 2017: Vision Research
Kara J Emery, Vicki J Volbrecht, David H Peterzell, Michael A Webster
Observers with normal color vision vary widely in their judgments of color appearance, such as the specific spectral stimuli they perceive as pure or unique hues. We examined the basis of these individual differences by using factor analysis to examine the variations in hue-scaling functions from both new and previously published data. Observers reported the perceived proportion of red, green, blue or yellow in chromatic stimuli sampling angles at fixed intervals within the LM and S cone-opponent plane. These proportions were converted to hue angles in a perceptual-opponent space defined by red vs...
January 3, 2017: Vision Research
John E Sparrow, Joseph A LaBarre, Brianna Sargent Merrill
Motion-induced blindness (MIB; Bonneh, Cooperman, & Sagi, 2001) is a visual phenomenon in which salient, stationary high-contrast targets are perceived to disappear and reappear when viewed within a moving background mask. The present study examined the effects of depth ordering (three levels) and mask motion coherence (0%, 50%, and 100% coherence of the mask elements), as well as the interaction effects between these two variables, especially taking note of between-subject variation. It is clear that individuals experience different amounts of MIB, indexed using average, cumulative, and normalized measures...
January 2, 2017: Vision Research
Francesca C Fortenbaugh, Lynn C Robertson, Michael Esterman
Visual spatial attention is a critical process that allows for the selection and enhanced processing of relevant objects and locations. While studies have shown attentional modulations of perceived location and the representation of distance information across multiple objects, there remains disagreement regarding what influence spatial attention has on the underlying structure of visual space. The present study utilized a method of magnitude estimation in which participants must judge the location of briefly presented targets within the boundaries of their individual visual fields in the absence of any other objects or boundaries...
December 30, 2016: Vision Research
Amit Lerner, Ron Shmulevitz, Howard I Browman, Nadav Shashar
Polarized light detection has been documented in only a small number of fish species. The benefit of polarization vision for fish is not fully understood, nor is the transduction mechanism that underlies it. Past studies proposed that one possible advantage of polarization vision is that it enhances the contrast of zooplankton targets by breaking their transparency. Here, we used an optomotor apparatus to test the responses of the planktivorous Hardyhead silverside fish Atherinomorus forskalii (Atherinidae) to vertical unpolarized (intensity) and polarized gratings...
December 30, 2016: Vision Research
Benjamin Balas, Alyson Saville
Face exposure during development determines adults' abilities to recognize faces and the information they use to process them. Individual differences in the face categories represented in the visual environment can lead to category-specific deficits for recognizing faces that are atypical of observer's experience (e.g. the other-race effect). But what happens when observers have limited opportunities to learn about faces in general? In previous work, we found that observers from depopulated areas have poorer face recognition performance than observers from larger communities, suggesting that impoverished face experience limits face processing broadly...
December 23, 2016: Vision Research
Jamie K Opper, Vicki J Volbrecht
Hue perception has been shown to differ for the same stimulus when presented to the temporal and the nasal areas of the retina. The present study investigated perceptual differences in stimuli viewed binocularly or monocularly in the peripheral retina to determine how hue information combines across the two retinas for a stimulus falling on the temporal retina of one eye and the nasal retina of the other. A hue-scaling procedure was utilized to ascertain hue perception for three color- and binocular-normal observers viewing monochromatic stimuli (450-670nm, 20nm steps) ranging in size from 1...
December 22, 2016: Vision Research
Greta Vilidaite, Daniel H Baker
Internal noise is a fundamental limiting property on visual processing. Internal noise has previously been estimated with the equivalent noise paradigm using broadband white noise masks and assuming a linear model. However, in addition to introducing noise into the detecting channel, white noise masks can suppress neural signals, and the linear model does not satisfactorily explain data from other paradigms. Here we propose estimating internal noise from a nonlinear gain control model fitted to contrast discrimination data...
December 22, 2016: Vision Research
Muhammad A J Qadri, Robert G Cook
The biological mechanisms used to categorize and recognize behaviors are poorly understood in both human and non-human animals. Using animated digital models, we have recently shown that pigeons can categorize different locomotive animal gaits and types of complex human behaviors. In the current experiments, pigeons (go/no-go task) and humans (choice task) both learned to conditionally categorize two categories of human behaviors that did not repeat and were comprised of the coordinated motions of multiple limbs...
December 22, 2016: Vision Research
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