Competitive interactions occur during working memory encoding and iconic memory but not during working memory maintenance.

Abstract

Competition has typically been manipulated by simultaneously presenting two visual items within the same receptive field (RF). Such competition originates at perception, and is associated with longer reaction times, reduced BOLD response and reduced neural firing. Previously we observed that perceptual competition affects working memory (WM) performance. In that study we manipulated competition during WM encoding by varying the spatial proximity between two simultaneously presented items (Near vs. Far conditions). Participants were required to report the colour of a target item on a colour wheel. Relative to the Far condition, the Near condition was associated with reduced WM precision and an increase in the number of times the colour of the un-cued item was erroneously reported. Here four experiments are presented, where competition was manipulated between items in iconic or working memory, but not during perception. Two items were presented sequentially, and the second item appeared either in close or distant spatial proximity to the first item (Near vs. Far conditions). The temporal interval between the first (S1) and second (S2) item was either 0ms (Experiment 1), 500ms (Experiment 2), or 1000ms (Experiment 3). In Experiment 1, relative to the Far condition, the Near condition was associated with reduced precision and more reports of the colour of the un-cued item. However, in Experiments 2 and 3 these effects were absent. In Experiment 4 we encouraged participants to maintain the two items in either the precise spatial locations in which they were presented by adding a location judgment task to 25% of trials. Despite this manipulation, there was no evidence of competition. We conclude that WM performance is vulnerable to competition when items compete during WM encoding or within iconic memory, but not when the competition can only occur within WM.

Meeting abstract presented at VSS 2016