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Stefan Van der Stigchel; Oculomotor competition when working memory is occupied. Journal of Vision 2008;8(6):120. doi: 10.1167/8.6.120.
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© ARVO (1962-2015); The Authors (2016-present)
Because our eyes can only fixate one location at a time, there is a continuous competition for gaze between the visual elements. Crucial for successful goal-directed behavior is therefore the correct selection of the relevant element (‘target’) in the presence of competing but irrelevant elements. How does the brain determine which element to select and which to ignore? By adding a dual task to a visual search experiment, the different cognitive processes involved in oculomotor target selection can be revealed. Here, two experiments are presented in which participants were required to make an eye movement to a target while ignoring a single distractor. Simultaneously, participants performed an n-back test which is known to occupy working memory (e.g. n = 2). Previous studies have indicated that performance on the antisaccade task is impaired when an n-back test is added. However, the effects of an occupied working memory on inhibiting task-irrelevant items is unknown within the oculomotor domain. In the first experiment, more erroneous eye movements were made to the distractor when working memory was occupied. However, there was no increased distractor effect on saccade latency with a 2-back task. In a second experiment, there was no visual search necessary to find the target. Again, no increased distractor effect was observed. Saccade trajectories deviated away from the distractor, but saccade deviations were similar for the different memory conditions, although the overall saccade latency was lower when working memory was occupied. Because there was no increased distractor effect on saccade latencies and trajectories, the results indicate that oculomotor inhibition of an task-irrelevant distractor is not mediated by mechanisms involved in working memory. However, the finding that more erroneous eye movements were made to the distractor when working memory systems were occupied seems to indicate that these processes are involved in keeping task instructions active.
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