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Fabrice Arcizet, James Bisley; The effect of a top-down cue on spread attention in the macaque. Journal of Vision 2008;8(6):990. doi: 10.1167/8.6.990.
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© ARVO (1962-2015); The Authors (2016-present)
Attention can be allocated to different regions of the visual scene according to the attentional priority of the objects in the scene. These priorities are represented by activity in the priority map in the lateral intraparietal area (LIP). In this study, we are interested in understanding how the brain focuses or spreads attention. To examine this, we trained two monkeys to perform a change blindness task. A trial started when the monkey fixated a central white spot during a delay of 1100 ms. Then, a combination of 1, 2, 4 or 8 oriented bars was flashed for 500 ms at equal eccentricities. After a gap of 50–150 ms, the bars reappeared for 1000 ms. In some trials, one of the bars was rotated 90 deg when it reappeared. The monkey had to saccade to this bar within 600 ms to be rewarded. In the remaining trials, no bar was rotated and the monkey was rewarded for maintaining fixation. The behavioral performance was recorded in term of the percentage of correct responses. Both monkeys showed a decrease in performance according to the number of distractors, suggesting that attention was spread and that the amount of attention at a location decreased as the number of bars increased. In another block of trials, to implement top-down attention, only 1 of the 8 stimulus locations could have the rotating stimulus — the stimuli in the 7 remaining locations will not rotate for the entire block. The addition of top-down attention increased performances indicating that attention is focused to this location. However, performance with top-down attention was worse than performance when only 1 stimulus was presented, suggesting that the presence of distractors limits the amount of attention and that the distractors are not completely suppressed on the priority map.
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