Latest News

We have just published a study in Journal of Vision comparing different tasks being used to measure ocular dominance plasticity.

In the recent decade, studies have shown that short-term monocular deprivation strengthens the deprived eye’s contribution to binocular vision. However, the magnitude of the change in eye dominance after monocular deprivation (i.e., the patching effect) has been found to be different between different methods and within the same method. There are three possible explanations for the discrepancy. First, the mechanisms underlying the patching effect that are probed by different measurement tasks might exist at different neural sites. Second, the test–retest variability of the same test can produce inconsistent results. Third, the magnitude of the patching effect itself within the same observer can vary across separate days or experimental sessions. To explore these possibilities, we assessed the test–retest reliability of the three most commonly used tasks (binocular rivalry, binocular combination, and dichoptic masking) and the repeatability of the shift in eye dominance after short-term monocular deprivation for each of the task. Two variations for binocular phase combination were used, at one and many contrasts of the stimuli. Also, two variations for dichoptic masking were employed; the orientation of the mask grating was either horizontal or vertical. Thus, five different tasks were evaluated. We hoped to resolve some of the inconsistencies reported in the literature concerning this form of visual plasticity. In this study, we also aimed to recommend a measurement method that would allow us to better understand its physiological basis and the underpinning of visual disorders.

We are pleased to announced that the lab has received initial funding from the Vision Health Research Network of the FRQ-S. This will fund a project investigating “Adaptation of visual processing to noisy signals in normal vision and Visual Snow Syndrome”.

To perceive the world through sight, the visual system must perform sophisticated processing on the input from the eyes. The visual input is noisy, and so the information regarding what is being seen must be inferred. Recent findings suggest that the brain may adapt its processing to the noise in the input. This can be seen in studies of healthy vision, in studies of changes with age, and in disease. This raises the question of whether these proposed adaptations are responsible for some of the symptoms of those diseases. In this project, I set out to establish whether these adaptations occur, with a specific focus on Visual Snow Syndrome. This condition has only recently gained interest as an area of study. Its sufferers experience a “TV static” noise across their visual field. My hypothesis is that in healthy vision there is a homeostatic balance controlling the effects of visual noise. In Visual Snow Syndrome, I would therefore hypothesise that this balance has been disturbed. For example, the palinopsia experienced by some patients may be due to abnormal temporal integration. In my project, I will develop behavioural methods to measure the strength of the visual noise affecting these individuals. I will also develop methods to measure the adaptive responses that this noise may have elicited. These experiments will use online psychophysical testing to reach a large cohort. Should this study find the hypothesised imbalance to be responsible, then that would raise the possibility of “re-balancing” the system to cure the condition.

We have just published a study in Journal of Vision on using attention to manipulate ocular dominance.

In binocular vision, even without conscious awareness of eye of origin, attention can be selectively biased toward one eye by presenting a visual stimulus uniquely to that eye. Monocularly directed visual cues can bias perceptual dominance, as shown by studies using discrete measures of percept changes in continuous-flash suppression. Here, we use binocular rivalry to determine whether eye-based visual cues can modulate eye balance using continuous percept reporting. Using a dual-task versus single-task paradigm, we investigated whether the attentional load of these cues differentially modulates eye balance. Furthermore, both color-based and motion-based cue stimuli, non-overlaid and peripheral to the rivalry grating stimuli, were used to determine whether shifts in eye balance were stimulus specific. Aligned to cue stimulus onset, time series of percept reports were constructed and averaged across trials and participants. Specifically, for the monocular attention conditions, we found a significant shift in eye balance toward the cued eye and a significant difference in the time taken to switch from the dominating percept, regardless of whether the attention stimuli is color based or motion based. Although we did not find a significant main effect of attentional load, we found a significant interaction effect between the attentionally cued eye and attentional load on the shift in eye balance, indicating an influence of monocular attention on the shift in eye balance.

It seems appropriate for my first news entry to be the launch of this website. It is created using Hugo based on the Anatole theme. I am looking forward to developing this site further over the next few months.