Abstract
The general goal of this work is to develop a visual search task for macaque monkeys that allows decomposition of functionally distinct processing stages through the analytic logic of separate modifiability. Monkeys are trained to search for an elongated color singleton among distractors. The orientation of the singleton specifies the stimulus-response mapping rule; pro-saccade for a vertical singleton and anti-saccade for a horizontal singleton. Distractors could be square or elongated. Elongated distractors create a new task demand; singleton and distractor orientation can be congruent (specifying saccades to same endpoint) or incongruent (saccades to opposite endpoints). Performance of this task requires multiple, sequential operations: localizing of the color singleton, encoding the shape of the singleton, encoding the instructed stimulus-response mapping, selecting the endpoint of the saccade, and preparing and initiating the saccade. We assessed the effects of stimulus-response mapping and target-distractor congruence on response time (RT) and peak saccade velocity (PV). We observed that RT was prolonged in anti-saccade (mean = 336 ms) relative to pro-saccade (238 ms) trials. We also observed that RT was prolonged on incongruent (318 ms) relative to congruent (278 ms) trials. Saccade velocity was also influenced by task demands. PV was lower in anti-saccade (mean = 394 deg/sec) relative to pro-saccade trials (411 deg/sec), and PV was lower on incongruent (398 deg/sec) vs. congruent (403 deg/sec) trials. These results extend prior studies of behavioral effects of sensory and cognitive interference in monkeys and humans. The magnitude of singleton-distractor congruency offers a new measure of the efficiency of attentional filtering in monkeys. These results will guide future studies of the neural correlates of the sequential operations necessary to accomplish this task.
Meeting abstract presented at VSS 2018