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Principal Investigator: Preeti Verghese, Ph. D.

Current work in my lab can be broadly divided into three areas of interest:

Target selection in the real world:
When we interact with our surroundings we are often looking at or reaching for an object of interest that is embedded in the clutter of daily life. Successful interaction with our surroundings requires that several processes work in concert. These include low-level factors such as how the target differs from its surroundings, on mid-level factors that organize the scene into regions and surfaces, and on higher-level factors such as attention, prior knowledge and expectation. In my lab, we use psychophysics as well as high-density electroencephalography (EEG) combined with a process that localizes the cortical sources of the scalp potentials to determine the neural populations that implement these processes. Our specific questions are: When attention is directed to a target, how do the task and surrounding context influence selectivity for target location and for its characteristic features? How does evidence for the target's identity evolve over time and how do attention and task demands influence the way in which local evidence is combined?

Strategies for efficient visual information gathering:
In daily life, we generally explore our surroundings visually before we plan action. Because visibility is poorer in the periphery we must move our eyes to gather task-relevant information, but which locations should an observer fixate? Research with single-target search paradigms indicates that observers saccade to salient and likely target locations. This latter strategy, although efficient for single targets, is inefficient under more demanding conditions that involve cluttered environments and time pressure We examine eye movement strategies for complex information gathering under time pressure using a laboratory task that presents an unknown number of targets in noise. Under these conditions, we propose that the most efficient strategy is to saccade to the most uncertain locations, or locations that appear equally likely to be target or noise. Our studies indicate that observers do not use an efficient strategy, but instead make eye movements to locations where the target is clearly visible. We are currently investigating the relation between latency and saccade strategy as well as the effect of immediate feedback, and reward.

Depth perception in central vision loss:
Age-related macular degeneration affects central vision and impairs high acuity visual function. Individuals with AMD complain about difficulty with everyday tasks such as reading, recognizing faces and watching television. More recent studies report difficulty with eye-hand coordination and grasping, consistent with data showing that the majority of individuals with AMD have little depth perception. Stereopsis can be impaired when the two eyes have very disparate patterns of vision loss, particularly when the stronger eye determines binocular gaze direction, without regard to the functional status of the corresponding fixation location in the other eye. Loss of depth perception not only impacts tasks requiring eye hand coordination, but it can have serious consequences for mobility and obstacle avoidance. In this group of studies we evaluate the potential for binocular vision and examine the potential to restore stereopsis in individuals with AMD, by encouraging individuals to use fixation loci in the two eyes that have similar function.

Last updated: Wed, March 28, 2013
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Preeti Verghese.