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Vision Research

Chloe Callahan-Flintoft, Brad Wyble
The visual system is able to detect targets according to a variety of criteria, such as by categorical (letter vs digit) or featural attributes (color). These criteria are often used interchangeably in rapid serial visual presentation (RSVP) studies but little is known about how rapidly they are processed. The aim of this work was to compare the time course of attentional selection and memory encoding for different types of target criteria. We conducted two experiments where participants reported one or two targets (T1, T2) presented in lateral RSVP streams...
September 16, 2017: Vision Research
L Becker, D T Smith, T Schenk
The familiarity effect (FE) refers to the phenomenon that it is easier to find an unfamiliar element on a background of familiar elements than vice versa. In this study, we examined the FE in texture segmentation while recording event-related brain potentials with the aim to find out which processing stages were influenced by familiarity. In two experiments, with different levels of texture homogeneity, the N1, the N2p and the P3 components were investigated. It was found that the FE in texture segmentation is associated with a modulation of the early N1 and of the intermediate N2p component for homogeneous textures...
September 14, 2017: Vision Research
Michael J Simpson
The region of far peripheral vision, beyond 60 degrees of visual angle, is important to the evaluation of peripheral dark shadows (negative dysphotopsia) seen by some intraocular lens (IOL) patients. Theoretical calculations show that the limited diameter of an IOL affects ray paths at large angles, leading to a dimming of the main image for small pupils, and to peripheral illumination by light bypassing the IOL for larger pupils. These effects are rarely bothersome, and cataract surgery is highly successful, but there is a need to improve the characterization of far peripheral vision, for both pseudophakic and phakic eyes...
September 9, 2017: Vision Research
Hugh R Wilson
It is well known that small orientation differences between two monocular gratings fuse to generate a stereoscopic perception of tilt, while large differences trigger binocular rivalry. In addition, unequal monocular contrasts combine nonlinearly to generate binocular contrast. A nonlinear neural model is developed here to account for binocular contrast, fusion at small orientation differences, and rivalry at large differences. The model also accounts for hysteresis in the transition between fusion and rivalry...
September 8, 2017: Vision Research
Jessica Holmin, Mark Nawrot
To successfully navigate throughout the world, observers must rapidly recover depth information. One depth cue that is especially important for a moving observer is motion parallax. To perceive unambiguous depth from motion parallax, the visual system must integrate information from two different proximal signals, retinal image motion and a pursuit eye movement. Previous research has shown that aging affects both of these necessary components for motion parallax depth perception, but no research has yet investigated how aging affects the mechanism for integrating motion and pursuit information to recover depth from motion parallax...
September 5, 2017: Vision Research
Eva Chadnova, Alexandre Reynaud, Simon Clavagnier, Robert F Hess
Recently, psychophysical studies have shown that humans with amblyopia do have binocular function that is not normally revealed due to dominant suppressive interactions under normal viewing conditions. Here we use magnetoencephalography (MEG) combined with dichoptic visual stimulation to investigate the underlying binocular function in humans with amblyopia for stimuli that, because of their temporal properties, would be expected to bypass suppressive effects and to reveal any underlying binocular function...
August 31, 2017: Vision Research
Brandon A Coughlin, Derrick J Feenstra, Susanne Mohr
Müller cells are one of the primary glial cell types found in the retina and play a significant role in maintaining retinal function and health. Since Müller cells are the only cell type to span the entire width of the retina and have contact to almost every cell type in the retina they are uniquely positioned to perform a wide variety of functions necessary to maintaining retinal homeostasis. In the healthy retina, Müller cells recycle neurotransmitters, prevent glutamate toxicity, redistribute ions by spatial buffering, participate in the retinoid cycle, and regulate nutrient supplies by multiple mechanisms...
August 30, 2017: Vision Research
Rebecca A Champion, Paul A Warren
Speed perception is vital for safe activity in the environment. However, considerable evidence suggests that perceived speed changes as a function of stimulus contrast, with some investigators suggesting that this might have meaningful real-world consequences (e.g. driving in fog). In the present study we investigate whether the neural effects of contrast on speed perception occur at the level of local or global motion processing. To do this we examine both speed discrimination thresholds and contrast-dependent speed perception for two global motion configurations that have matched local spatio-temporal structure...
August 30, 2017: Vision Research
Timothy J Gawne, Alexander H Ward, Thomas T Norton
In infant tree shrews, exposure to narrow-band long-wavelength (red) light, that stimulates long-wavelength sensitive cones almost exclusively, slows axial elongation and produces hyperopia. We asked if red light produces hyperopia in juvenile and adolescent animals, ages when plus lenses are ineffective. Animals were raised in fluorescent colony lighting (100-300 lux) until they began 13days of red-light treatment at 11 (n=5, "infant"), 35 (n=5, "juvenile") or 95 (n=5, "adolescent") days of visual experience (DVE)...
August 29, 2017: Vision Research
Marcus Nyström, Richard Andersson, Diederick C Niehorster, Ignace Hooge
Despite early reports and the contemporary consensus on microsaccades as purely binocular phenomena, recent work has proposed not only the existence of monocular microsaccades, but also that they serve functional purposes. We take a critical look at the detection of monocular microsaccades from a signal perspective, using raw data and a state-of-the-art, video-based eye tracker. In agreement with previous work, monocular detections were present in all participants using a standard microsaccade detection algorithm...
August 23, 2017: Vision Research
Rebecca Holmes, Michelle Victora, Ranxiao Frances Wang, Paul G Kwiat
Temporal summation is an important feature of the visual system which combines visual signals that arrive at different times. Previous research estimated complete summation to last for 100ms for stimuli judged "just detectable." We measured the full range of temporal summation for much weaker stimuli using a new paradigm and a novel light source, developed in the field of quantum optics for generating small numbers of photons with precise timing characteristics and reduced variance in photon number. Dark-adapted participants judged whether a light was presented to the left or right of their fixation in each trial...
August 19, 2017: Vision Research
Christoph Witzel, J Kevin O'Regan, Sabrina Hansmann-Roth
This study investigates systematic individual differences in the way observers perceive different kinds of surface properties and their relationship to the dress, which shows striking individual differences in colour perception. We tested whether these individual differences have a common source, namely differences in perceptual strategies according to which observers attribute features in two-dimensional images to surfaces or to their illumination. First, we reanalysed data from two previous experiments on the dress and colour constancy...
August 18, 2017: Vision Research
Hannah C Agnew, Karin S Pilz
The visual system has an extraordinary capability to extract categorical information from complex scenes. Age-related deficits in visual temporal processing have been found with both low-level and high-level stimuli. However, it is unknown to which extent those deficits extend to the processing of complex scenes. Here, we investigated the temporal characteristics of natural scene categorisation in healthy ageing. Using a backward masking paradigm, we asked young-old (aged 59-70), old-old (aged 70+) and younger adults (18-31years) to perform a go/no-go task, in which they had to respond to images of animals whilst ignoring images of landscapes...
August 17, 2017: Vision Research
Junzhu Su, Hongjing Lu
The ability to localize moving joints of a person in action is crucial for interacting with other people in the environment. However, it remains unclear how the visual system encodes the position of joints in a moving body. We used a paradigm based on a well-known phenomenon, the flash-lag effect, to investigate the mechanisms underlying joint localization in bodily movements. We first found that observers perceived a strong flash-lag effect in biological motion: when a briefly-flashed dot was presented physically in perfect alignment with a continuously moving limb, the flash dot was perceived to lag behind the position of the moving joint...
August 14, 2017: Vision Research
Maria J Barraza-Bernal, Iliya V Ivanov, Svenja Nill, Katharina Rifai, Susanne Trauzettel-Klosinski, Siegfried Wahl
The sustained component of visual attention lowers the perceptual threshold of stimuli located at the attended region. Attentional performance is not equal for all eccentric positions, leading to variations in perception. The location of the preferred retinal locus (PRL) for fixation might be influenced by these attentional variations. This study investigated the relation between the placement of sustained attention and the location of a developed PRL using simulations of central scotoma. Thirteen normally sighted subjects participated in the study...
August 10, 2017: Vision Research
Elena Segal, Ido Perlman
Chromaticity type horizontal cells (C-type HCs) are the first retinal neurons exhibiting spectral information processing in cold-blooded vertebrates. The simple input of hyperpolarizing responses of cone photoreceptors is transformed in the C-type HCs into spectral opponent output. Nitric oxide (NO), a known background neuromodulator in the distal retina, was tested here for its effects upon spectral information processing by C-type HCs in the retina of turtle. Photoresponses were intracellularly recorded from C-type HCs, using light stimuli of different wavelength, applied over backgrounds of different wavelengths, and changing retinal NO level...
August 7, 2017: Vision Research
M Elizabeth Hartnett, Wolfgang Baehr, Yun Z Le
This overview introduces contributions to a special issue on causes of vision loss from diabetes mellitus, focusing on the retina and also the cornea. Diabetic retinopathy is the most common and leading cause of vision loss among people with diabetes. Research to detect early symptoms, understand mechanisms leading to diabetic eye disease, and the development of treatments is a highly active research area, with currently about 2000 scientific publication per year. We provide a series of 27 comprehensive reviews and research articles from leading experts in the field...
August 4, 2017: Vision Research
Thomas W Gardner, Jeffrey M Sundstrom
This paper presents a new approach to the prevention and treatment of early stage diabetic retinopathy before vision is severely impaired. This approach includes two major steps. The first step is to understand the mechanisms of vision impairment and classify diabetic retinopathy on the basis of pathophysiologic adaptations, rather than on the presence of advanced pathologic lesions, as defined by current clinical practice conventions. The second step is to develop patient-specific molecular diagnoses of diabetic retinopathy so that patients can be treated based on their individual characteristics, a process analogous to the individualized diagnosis and treatment of cancer patients...
August 2, 2017: Vision Research
Frances Rucker, Mark Henriksen, Tiffany Yanase, Christopher Taylor
A previous experiment showed that blue light (as a component of white light) protected against low temporal frequency dependent eye growth. This experiment investigated the role of temporal contrast. White leghorn chicks were exposed to white (with blue) or yellow (without blue) LED lighting modulated at either low (0.2Hz) or high (10Hz) temporal frequencies. Four cone contrast conditions were used: low (16%), medium (32%), medium-high (60%) and very-high (80%). Chicks were exposed to the lighting condition for 3days (mean 680lux)...
August 1, 2017: Vision Research
Eun-Ah Ye, Li Liu, Jena J Steinle
Hyperglycemia is a significant risk factor for diabetic retinopathy and induces multiple biochemical changes, including inflammation and endothelial dysfunction in the retina. Alterations in microRNA expression have been implicated in the pathological responses of diabetic retinopathy and the manipulation of microRNA may provide powerful strategy for therapeutics. Among the predicted targets of miR-15a and -16 are TGF-beta3, SMAD2/3, and VEGF, all of which are known to play a role in vascular endothelial functions...
July 31, 2017: Vision Research
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