Abstract
Consistent and robust boosts to visual working memory capacity are observed when color-location arrays contain duplicated colors. It remains unclear exactly why this boost occurs. The prevailing hypothesis suggests that duplicated colors are encoded as one perceptual group. If so, then we should observe not only higher working memory capacity overall, but specifically an improved ability to remember unique colors from displays including redundancy compared with displays without redundancy. This hypothesis also suggests that less effort should be required to retain displays including duplicate colors. I recorded gaze position and pupil sizes during a visual change detection task including displays with all unique colors, two items with a common color, or three items with a common color. Increased redundancy was indeed associated with higher estimated working memory capacity, both for tests of uniquely-colored items and duplicates. Redundancy was also associated with decreased pupil size during retention, consistent with the hypothesis that encoding multiple items as a group eases memory for the visual array. I tested samples of young adults (19-33 years old) and healthy elderly adults (65-82 years old) in order to learn whether these benefits, which could depend on the ability to maintain color-location bindings, changed with age. Like young adults, elderly adults benefited from color redundancy, though their estimated working memory capacities were lower overall. However, more redundancy in the display was needed for elderly adults to show the same increases in capacity as young adults. The pupillometry data from the elderly adults likewise suggested that the impact of redundancy on effort was attenuated. Overall, these results support the contention that feature redundancy affords perceptual grouping, which reduces the amount of information to-be-maintained from a visual display.
Meeting abstract presented at VSS 2017