The goal of this project is to examine the malleability of the visual system, in particular, its ability to resolve stimuli over time. Previous research has shown that people improve over time dramatically in some visual tasks but not in others. Tasks that involve the ability to resolve stimuli quickly consistently exhibit improvement with practice. One such task is backward masking, in which a visual target, a display to be identified or recognized, is followed closely in time by a visual mask, a display that lights up all the places on the screen where parts of targets could possibly appear. One hypothesis is that practice effects in these tasks are the result of learning to process the information more quickly or over smaller time frames. Several real-world tasks, such as landing a plane and hitting a baseball, profit from such rapid visual processing. There are other activities, however, that require one to integrate information over time, for example, watching television and computer screens and using fluorescent lights (this research will use a task that simulates these examples in a controlled and sensitive fashion). If improvement on backward masking is the result of learning to process information in smaller time frames, then performance on tasks that require integration over longer time frames should be impaired. The experiments will test for this impairment by training people either on tasks that require rapid processing or on tasks that require integration and looking for the effect of improvement on the trained task on performance on tasks requiring the opposite skills. The experiments will also examine individual differences in performance on these tasks. Some people are quite good at backward masking from the very beginning and others are quite bad. Will those people who are good at backward masking be bad at integration tasks and vice versa? Performance on backward masking decreases with age. Does performance on integration tasks improve with age? Are these individual differences reversible (i.e., the result of prior training and experience) or the result of physiological differences and changes in the visual system? The experiments will help resolve these various issues.
