Read by QxMD icon Read

Vision Research

Chunming Liu, Stefanie A Drew, Eric Borsting, Amy Escobar, Lawrence Stark, Christopher Chase
The purpose of this study is to examine the potential relationship between tonic accommodation (TA), near work induced TA-adaptation and the steady state closed-loop accommodation response (AR). Forty-two graduate students participated in the study. Various aspects of their accommodation system were objectively measured using an open-field infrared auto-refractor (Grand Seiko WAM-5500). Tonic accommodation was assessed in a completely dark environment. The association between TA and closed-loop AR was assessed using linear regression correlations and t-test comparisons...
October 17, 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
John T Serences
The capacity to briefly memorize fleeting sensory information supports visual search and behavioral interactions with relevant stimuli in the environment. Traditionally, studies investigating the neural basis of visual short term memory (STM) have focused on the role of prefrontal cortex (PFC) in exerting executive control over what information is stored and how it is adaptively used to guide behavior. However, the neural substrates that support the actual storage of content-specific information in STM are more controversial, with some attributing this function to PFC and others to the specialized areas of early visual cortex that initially encode incoming sensory stimuli...
October 4, 2016: Vision Research
Lisa A Ostrin, Vivian Choh, Christine F Wildsoet
The chick is widely used in studies of eye growth regulation and myopia. The aim of this study was to explore the utility of pattern (p)ERG as a tool to assess retinal function in such studies. Effects of optical defocus and diffusing blur, manipulations used to alter eye growth experimentally, were evaluated. PERGs were recorded from White-Leghorn chickens, using a checkerboard pattern, including 8 spatial frequencies (0.05-2.2c/d SF), 13 contrast levels (1-100%), and 8 temporal reversal frequencies (0.5-20Hz)...
September 28, 2016: Vision Research
Takayuki Osugi, Yuji Takeda, Ikuya Murakami
We investigated the influence of attentional inhibition on the perceived duration of a brief visual event. Although attentional capture by an exogenous cue is known to prolong the perceived duration of an attended visual event, it remains unclear whether time perception is also affected by subsequent attentional inhibition at the location previously cued by an exogenous cue, an attentional phenomenon known as inhibition of return. In this study, we combined spatial cuing and duration judgment. After one second from the appearance of an uninformative peripheral cue either to the left or to the right, a target appeared at a cued side in one-third of the trials, which indeed yielded inhibition of return, and at the opposite side in another one-third of the trials...
September 28, 2016: Vision Research
David A Gonzalez, Ewa Niechwiej-Szwedo
The contribution of binocular vision to the performance of reaching and grasping movements has been examined previously using single reach-to-grasp movements. However, most of our daily activities consist of more complex action sequences, which require precise temporal linking between the gaze behaviour and manual action phases. Many previous studies found a stereotypical hand-eye coordination pattern, such that the eyes move prior to the reach initiation. Moving the eyes to the target object provides information about its features and location, which can facilitate the predictive control of reaching and grasping...
September 26, 2016: Vision Research
Yangyang Du, Fan Zhang, Yongchao Wang, Taiyong Bi, Jiang Qiu
Perceptual learning is a phenomenon in which intensive training for a perceptual task may lead to significant improvement in the task performance. So far, the characteristics of the perceptual learning of facial expressions have not been investigated. In the current study, we trained subjects to distinguish facial expressions. With eight days of training, the subjects' discrimination performance improved significantly, and this improvement was generalized to faces with the same expression but different gender as the trained face...
September 24, 2016: Vision Research
Ignace Hooge, Kenneth Holmqvist, Marcus Nyström
Most modern video eye trackers use the p-CR (pupil minus CR) technique to deal with small relative movements between the eye tracker camera and the eye. We question whether the p-CR technique is appropriate to investigate saccade dynamics. In two experiments we investigated the dynamics of pupil, CR and gaze signals obtained from a standard SMI Hi-Speed eye tracker. We found many differences between the pupil and the CR signals. Differences concern timing of the saccade onset, saccade peak velocity and post-saccadic oscillation (PSO)...
September 22, 2016: Vision Research
Michael Morgan, Barbara Dillenburger
The magnitude of the Poggendorff bias in perceived collinearity was measured with a 2AFC task and roving pedestal, and was found to be in the region of 6-8 deg, within the range of previous estimates. Further measurements dissected the bias into several components: (1) The small (∼1 deg) repulsion of the orientation of the pointer from the parallel, probably localized in the part of the line near the intersection (2) A small (< 1 deg) location bias affecting the intersection of pointers and inducing lines; and (3) A larger (> 1 deg) bias in the orientation of virtual lines crossing the gap between two parallels, towards the orientation of the parallels, or equivalently (4) An orthogonal bias in actively constructing a virtual line across the gap...
September 21, 2016: Vision Research
David Chan, Jason Rajsic, Jay Pratt
University-based psychological research typically relies on the participation of undergraduate students for data collection. Using this particular sample brings with it several possible issues, including the self-scheduling done by the participants. Research on performance between students who sign up early versus late in the semester has been inconsistent. Some research report benefits for early participant semesters, while others find no differences between the two groups. Anecdotally, it seems that the former holds true, as many researchers worry about the data collected late in the semester, sometimes opting for more motivated earlier participants in the next semester...
September 21, 2016: Vision Research
J P De Vries, R Azadi, M R Harwood
Saccade latencies are known to increase for targets presented close to fixation. Recently, it was shown that not only target eccentricity, but the size of a proximal saccade target also plays a crucial role: latencies increase rapidly with increasing target size. Interestingly, these latency increases are greater than those typically found for other supra-threshold manipulations of target properties. Here we evaluate to what extent this phenomenon is distinct from known delays in saccade initiation and whether the phenomenon is truly related to the size of a proximal target...
September 21, 2016: Vision Research
Frederick A A Kingdom
A longstanding issue in vision research concerns whether the internal noise involved in contrast transduction is fixed or variable in relation to contrast magnitude. Previous attempts to resolve the issue have focused on the analysis of contrast discrimination data, despite the fact that the effects of internal noise on thresholds are necessarily compounded by the shape of the underlying transducer function. An alternative approach is to compare data obtained from a particular class of scaling experiment - one based on a comparison of perceived contrast differences - with data from discrimination experiments gathered across the full range of contrast...
September 21, 2016: Vision Research
Diego López-Alcón, Iván Marín-Franch, Vicente Fernández-Sánchez, Norberto López-Gil
The purpose of this work was to find plausible predictors among optical parameters that may explain the inter-individual differences in subjective amplitude of accommodation not explained by age. An exploratory multivariable regression analysis was carried out retrospectively on a dataset with 180 eyes from 97 subjects (ages ranged from 20 to 58years). Subjective amplitudes of accommodation were recorded with the use of a custom-made Badal system. A commercial aberrometer was used to obtain each eye's wavefront during the full range of accommodation...
September 14, 2016: Vision Research
Mark Georgeson, Stuart Wallis, Tim Meese, Daniel Baker
Our goal here is a more complete understanding of how information about luminance contrast is encoded and used by the binocular visual system. In two-interval forced-choice experiments we assessed observers' ability to discriminate changes in contrast that could be an increase or decrease of contrast in one or both eyes, or an increase in one eye coupled with a decrease in the other (termed IncDec). The base or pedestal contrasts were either in-phase or out-of-phase in the two eyes. The opposed changes in the IncDec condition did not cancel each other out, implying that along with binocular summation, information is also available from mechanisms that do not sum the two eyes' inputs...
August 26, 2016: Vision Research
Maria Vinas, Carlos Dorronsoro, Veronica Gonzalez, Daniel Cortes, Aiswaryah Radhakrishnan, Susana Marcos
Multifocal vision corrections are increasingly used solutions for presbyopia. In the current study we have evaluated, optically and psychophysically, the quality provided by multizone radial and angular segmented phase designs. Optical and relative visual quality were evaluated using 8 subjects, testing 6 phase designs. Optical quality was evaluated by means of Visual Strehl-based-metrics (VS). The relative visual quality across designs was obtained through a psychophysical paradigm in which images viewed through 210 pairs of phase patterns were perceptually judged...
August 2, 2016: Vision Research
Ali Bayram, Esin Karahan, Başar Bilgiç, Ahmet Ademoglu, Tamer Demiralp
The sensitivity of the sensory systems to temporal changes of the environment constitutes one of the critical issues in perception. In the present study, we investigated the human early visual system's dependency on the temporal frequency of visual input using fMRI. Blood oxygen level-dependent (BOLD) responses of the lateral geniculate nucleus (LGN) and primary visual cortex (V1) were investigated in a wide frequency range (6-46Hz) with fine frequency sampling (13 frequencies). Subject-specific functional-anatomic ROIs were derived from the combination of the anatomic template masks and the functional maps derived from multi-session fMRI analyses across all 13 stimulation conditions...
October 2016: Vision Research
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"