The research in my lab examines the neural processes, strategies and adaptations that humans use to interact with objects in the real world. We investigate these questions using psychophysics, eye movements, computational modeling and neuroimaging. Our goal is to understand the mechanisms of normal vision and action, as well as the basis of attention and visual adaptation in clinical populations. This work includes attention deficits in amblyopia, and the potential for binocular vision in individuals with age-related macular degeneration.
Macular degeneration affects the central retina, often causing asymmetrical damage to the two eyes. How does this asymmetrical loss affect stereopsis — the percept of depth generated by the small separation of image features in the two eyes?
Bilateral field loss due to maculopathy creates a scotoma that extends in depth — a volume scotoma. Morevoer the size of the scotoma depends on whether observers turn their eyes to track a target as it comes closer. This project investigates how the volume scotoma affects the ability to track oncoming targets in these individuals, and in controls with a simulated volume scotoma.
The Smith-Kettlewell Eye Research Institute (SKERI) is an NEI Institutional Training Grant Awardee. The grant was awarded to provide postdoctoral training in basic and clinical science relevant to translational vision research and rehabilitation.
The project investigates motion perception in individuals with vision loss due to central retinal lesion, but who retain healthy peripheral retina. Healthy peripheral retina is exquisitely sensitive to fast speeds, however, there is limited and conflicting information about motion processing in...
In this project we try to gain a better understanding of what visual strategies people use to gather information in the world.
There is continuing debate as to whether smooth pursuit relies on the foveation of a moving target, especially when the target is compact. Previous studies have shown that gaze is placed on the center-of-mass of a target during saccadic eye movements. This research aims to understand whether eye...
This project investigates the properties of smooth pursuit eye movements in individuals with macular degeneration. Commonly believed to be a fovea-linked eye movement, smooth pursuit has not been previously investigated in individuals with central field loss, despite its importance for tracking moving objects, such as vehicles or pedestrians on a busy street.
Eye-hand coordination in AMD
The project investigates the deficits in smooth pursuit in individuals with age-related macular degeneration within the framework of a Bayesian model.
This project investigates the interaction between central field loss (CFL) and vestibular function.
Stereopsis is important for tasks of daily living such as eye-hand coordination. It is best in central vision but is also mediated by the periphery. Previously we have shown that individuals with central-field loss who have residual stereopsis in the periphery perform better at an eye-hand-coordination task. Here we sought to determine what sets the limit of stereopsis, defined as the largest disparity that supports the sustained appearance of depth, in the near periphery in healthy individuals. We used a rigorous method to determine the uppermost limit of disparity. The disparity limit is the point at which the threshold for judging dichoptic separation between the half-images is equal to the monocular width-discrimination threshold. The disparity limit at 10° was a factor of 2–4 times larger than the fovea, regardless of the meridian tested. The increase in the disparity limit with eccentricity was shallow, similar to that of Panum's area. Within this disparity limit, disparity increment thresholds were comparable for foveal and peripheral targets, illustrating the significance and utility of peripheral stereopsis, especially in the absence of foveal stereopsis.
This project aims to improve visual function in individuals with age-related macular degeneration (AMD). AMD isassociated with central field loss that cannot be corrected optically. Individuals with AMD are often unaware of their scotoma and their eye movements follow more random patterns,...
Active visual search
Attention and Segmentation