Saccade target selection in visual search: the effect of information from the previous fixation

Abstract

This paper reports an analysis of saccades made during a task of visual search for a colour shape conjunction. The analysis concentrates on the saccade following the first saccade, thus complementing an earlier paper where the first saccades were analysed. The further analysis addresses the issue of what information might be held in trans-saccadic memory. As with the first saccade, incorrect second saccades tend to fall on distractors sharing one feature with the target. The proximity of the target to the fixation location immediately prior to the saccade is a very significant determinant of whether the saccade will reach the target. The results lead to the conclusion that in the majority of cases, choice of saccade destination is made afresh during each fixation with no carry-over from the previous fixation. However, in a small number of cases, second saccades are made after extremely brief fixation intervals. Although these saccades show a similar probability of reaching the target as those following longer fixations, it is argued that this sub-set of saccades are pre-programmed at the time of the preceding saccade.