Abstract
Attention plays a crucial role in the Stroop task, which requires attending to less automatically processed task-relevant attributes of stimuli and the suppression of involuntary processing of task-irrelevant attributes. The experiment assessed the allocation of attention by monitoring saccades and fixations throughout congruent and incongruent trials in a numerical version of the Stroop task. Participants viewed two stimulus arrays that differed regarding the amount of items and their numerical value. They judged by manual response which of the arrays contained more items. In the congruent condition the larger array of items consisted of numbers with higher value, e.g., 44444, than the numbers of the smaller array, e.g., 222. In the incongruent condition the larger array of items was composed of numbers with lower value, e.g., 22222, than the numbers of the smaller array, e.g., 444. Manual reaction times were slower in the incongruent than in the congruent condition, indicating that the task-irrelevant attribute - the value of the numbers - is processed involuntarily and slows down responding. Further, different viewing patterns were observed between congruent and incongruent trials. The direction of first saccades was guided by task-relevant information (more items) but in the incongruent condition directed more frequently towards task-irrelevant information (higher value). The data further suggest that the difference in the deployment of attention between conditions changes throughout a trial, likely reflecting the impact and resolution of the conflict. For instance, stimulus arrays in line with the correct response (more items) were attended for longer and fixations were longer for incongruent trials, with the second fixation and considering all fixations. By the time of the correct response, this latter difference between conditions was absent. Possible mechanisms underlying the allocation of attention as reflected by eye movement patterns in a conflict task are discussed.
Meeting abstract presented at VSS 2013