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Vision Research

Sérgio M C Nascimento, João M M Linhares, Cristina Montagner, Catarina A R João, Kinjiro Amano, Catarina Alfaro, Ana Bailão
One hypothesis to explain the aesthetics of paintings is that it depends on the extent to which they mimic natural image statistics. In fact, paintings and natural scenes share several statistical image regularities but the colors of paintings seem generally more biased towards red than natural scenes. Is the particular option for colors in each painting, even if less naturalistic, critical for perceived beauty? Here we show that it is. In the experiments, 50 naïve observers, unfamiliar with the 10 paintings tested, could rotate the color gamut of the paintings and select the one producing the best subjective impression...
November 29, 2016: Vision Research
Carole Peyrin, Stephen Ramanoël, Alexia Roux-Sibilon, Sylvie Chokron, Ruxandra Hera
Age-related macular degeneration (AMD) is characterized by a central vision loss. Here, we investigated the ability of AMD patients to process the spatial frequency content of scenes in their residual vision, depending of the luminance contrast level. AMD patients and normally-sighted elderly participants (controls) performed a categorization task involving large scenes (outdoors vs. indoors) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and non-filtered scenes (NF). Luminance contrast of scenes was equalized between stimuli using a root-mean square (RMS) contrast normalization...
November 29, 2016: Vision Research
Vivek Labhishetty, William R Bobier
Children with a progressing myopia exhibit an abnormal pattern of high accommodative lags coupled with high accommodative convergence (AC/A) and high accommodative adaptation. This is not predicted by the current models of accommodation and vergence. Reduced accommodative plant gain and reduced sensitivity to blur have been suggested as potential causes for this abnormal behavior. These etiologies were tested by altering parameters (sensory, controller and plant gains) in the Simulink model of accommodation...
November 25, 2016: Vision Research
Joseph Manzone, Shirin Davarpanah Jazi, Robert L Whitwell, Matthew Heath
Work by our group and others employed the within-participants variability in peak grip aperture as a 'just-noticeable-difference' (JND) in grasping. Notably, our group reported that grasping responses with decoupled spatial relations between stimulus and response (i.e., pantomime-grasping) produced JNDs that increased linearly with increasing target object size (i.e., adherence to Weber's law) and interpreted that result as law-based evidence of aperture shaping via relative visual information. In contrast, Utz et al...
November 25, 2016: Vision Research
Hinze Hogendoorn, Frans A J Verstraten, Hamish MacDougall, David Alais
Certain visual stimuli can have two possible interpretations. These perceptual interpretations may alternate stochastically, a phenomenon known as bistability. Some classes of bistable stimuli, including binocular rivalry, are sensitive to bias from input through other modalities, such as sound and touch. Here, we address the question whether bistable visual motion stimuli, known as plaids, are affected by vestibular input that is caused by self-motion. In Experiment 1, we show that a vestibular self-motion signal biases the interpretation of the bistable plaid, increasing or decreasing the likelihood of the plaid being perceived as globally coherent or transparently sliding depending on the relationship between self-motion and global visual motion directions...
November 25, 2016: Vision Research
Peter Olsson, David Wilby, Almut Kelber
Color guides many important behaviors in birds. Previously we have shown that the intensity threshold for color discrimination in the chicken depends on the color contrast between stimuli and their brightness. The birds could discriminate larger color contrasts and brighter colors in lower light intensities. We suggested that chickens use spatial summation of cone signals to maintain color vision in low light levels. Here we tested this hypothesis by determining the intensity thresholds of color discrimination using similar stimuli, patterns of grey tiles of varying intensity interspersed with color tiles, adjusted for this specific aim...
November 25, 2016: Vision Research
Melissa A Wilk, Brandon M Wilk, Christopher S Langlo, Robert F Cooper, Joseph Carroll
Adaptive optics (AO) imaging tools enable direct visualization of the cone photoreceptor mosaic, which facilitates quantitative measurements such as cone density. However, in many individuals, low image quality or excessive eye movements precludes making such measures. As foveal cone specialization is associated with both increased density and outer segment (OS) elongation, we sought to examine whether OS length could be used as a surrogate measure of foveal cone density. The retinas of 43 subjects (23 normal and 20 albinism; aged 6-67 years) were examined...
November 22, 2016: Vision Research
Jim Maarseveen, Hinze Hogendoorn, Frans A J Verstraten, Chris L E Paffen
Adaptation to the duration of a visual stimulus causes the perceived duration of a subsequently presented stimulus with a slightly different duration to be skewed away from the adapted duration. This pattern of repulsion following adaptation is similar to that observed for other visual properties, such as orientation, and is considered evidence for the involvement of duration-selective mechanisms in duration encoding. Here, we investigated whether the encoding of duration - by duration-selective mechanisms - occurs early on in the visual processing hierarchy...
November 19, 2016: Vision Research
Matt Craddock, Frank Oppermann, Matthias M Müller, Jasna Martinovic
The organization of visual processing into a coarse-to-fine information processing based on the spatial frequency properties of the input forms an important facet of the object recognition process. During visual object categorization tasks, microsaccades occur frequently. One potential functional role of these eye movements is to resolve high spatial frequency information. To assess this hypothesis, we examined the rate, amplitude and speed of microsaccades in an object categorization task in which participants viewed object and non-object images and classified them as showing either natural objects, man-made objects or non-objects...
November 19, 2016: Vision Research
Atanu Ghosh, Len Zheleznyak, Antoine Barbot, HaeWon Jung, Geunyoung Yoon
In the presence of optical blur at the fovea, blur adaptation can improve visual acuity (VA) and perceived image quality over time. However, little is known regarding blur adaptation in the peripheral retina. Here, we examined neural adaptation to myopic defocus at the fovea and parafovea (10° temporal retina) in both emmetropes and myopes. During the 60-min adaptation period, subjects (3 emmetropes and 3 myopes) watched movies with +2 diopters of defocus blur through a 6-mm artificial pupil in two separate, counter balanced sessions for each retinal location...
November 8, 2016: Vision Research
Philipp Nikolaus Hesse, Frank Bremmer
The existence of an association between numbers and space is known for a long time. The most prominent demonstration of this relationship is the spatial numerical association of response codes (SNARC) effect, describing the fact that participants' reaction times are shorter with the left hand for small numbers and with the right hand for large numbers, when being asked to judge the parity of a number (Dehaene et al., J. Exp. Psychol., 122, 371-396, 1993). The SNARC effect is commonly seen as support for the concept of a mental number line, i...
November 8, 2016: Vision Research
Francesca Pei, Stefano Jeffrey J Baldassi 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 (5-17 years) 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...
November 5, 2016: Vision Research
Oliver Braddick, Janette Atkinson, Natacha Akshoomoff, Erik Newman, Lauren B Curley, Marybel Robledo Gonzalez, Timothy Brown, Anders Dale, Terry Jernigan
Reduced global motion sensitivity, relative to global static form sensitivity, has been found in children with many neurodevelopmental disorders, leading to the "dorsal stream vulnerability" hypothesis (Braddick et al., 2003). Individual differences in typically developing children's global motion thresholds have been shown to be associated with variations in specific parietal cortical areas (Braddick et al., 2016). Here, in 125 children aged 5-12years, we relate individual differences in global motion and form coherence thresholds to fractional anisotropy (FA) in the superior longitudinal fasciculus (SLF), a major fibre tract communicating between parietal lobe and anterior cortical areas...
October 26, 2016: Vision Research
Ann E Elsner, Toco Y P Chui, Lei Feng, Hong Xin Song, Joel A Papay, Stephen A Burns
Large individual differences in cone densities occur even in healthy, young adults with low refractive error. We investigated whether cone density follows a simple model that some individuals have more cones, or whether individuals differ in both number and distribution of cones. We quantified cones in the eyes of 36 healthy young adults with low refractive error using a custom adaptive optics scanning laser ophthalmoscope. The average cone density in the temporal meridian was, for the mean ± SD, 43216 ± 6039, 27466 ± 3496, 14996 ± 1563, and 12207 ± 1278 cones /mm(2) for 270, 630, 1480, and 2070 microns from the foveal center...
October 25, 2016: Vision Research
Jutta Billino, Jürgen Hennig, Karl R Gegenfurtner
The neural circuits involved in oculomotor control are well described; however, neuromodulation of eye movements is still hardly understood. Memory guided saccades have been extensively studied and in particular neurophysiological evidence from monkey studies points to a crucial functional role of prefrontal dopamine activity. We exploited individual differences in dopamine regulation due to the well established COMT (catechol-O-methyltransferase) Val(158)Met polymorphism to explore the link between prefrontal dopamine activity and memory guided saccades in healthy subjects...
October 25, 2016: Vision Research
Kevin C Dieter, Jocelyn L Sy, Randolph Blake
Normal binocular vision emerges from the combination of neural signals arising within separate monocular pathways. It is natural to wonder whether both eyes contribute equally to the unified cyclopean impression we ordinarily experience. Binocular rivalry, which occurs when the inputs to the two eyes are markedly different, affords a useful means for quantifying the balance of influence exerted by the eyes (called sensory eye dominance, SED) and for relating that degree of balance to other aspects of binocular visual function...
October 17, 2016: Vision Research
David P McGovern, Kevin S Walsh, Jason Bell, Fiona N Newell
Both spatial and temporal context influence our perception of visual stimuli. For instance, both nearby moving stimuli and recently viewed motion can lead to biases in the perceived direction of a moving stimulus. Due to similarities in the spatial tuning properties of these spatial and temporal context-dependent effects, it is often assumed that they share a functional goal in motion processing and arise from common neural mechanisms. However, the psychophysical evidence concerning this assumption is inconsistent...
October 17, 2016: Vision Research
Mark A Georgeson, Andrew J Schofield
Combination of signals from the two eyes is the gateway to stereo vision. To gain insight into binocular signal processing, we studied binocular summation for luminance-modulated gratings (L or LM) and contrast-modulated gratings (CM). We measured 2AFC detection thresholds for a signal grating (0.75c/deg, 216ms) shown to one eye, both eyes, or both eyes out-of-phase. For LM and CM, the carrier noise was in both eyes, even when the signal was monocular. Mean binocular thresholds for luminance gratings (L) were 5...
October 14, 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...
October 13, 2016: Vision Research
Reshanne R Reeder
Visually perceiving a stimulus activates a pictorial representation of that item in the brain, but how pictorial is the representation of a stimulus in the absence of visual stimulation? Here I address this question with a review of the literatures on visual imagery (VI), visual working memory (VWM), and visual preparatory templates, all of which require activating visual information in the absence of sensory stimulation. These processes have historically been studied separately, but I propose that they can provide complimentary evidence for the pictorial nature of their contents...
October 7, 2016: Vision Research
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