Saccade Target Selection During Visual Search

AbstractFive experiments are reported in which eye movements were recorded while subjects carried out a visual search task. The aim was to investigate whether an accurate initial target directed saccade could be programmed. In Experiments 1–2, subjects moved their eyes to targets defined by colour, which were presented with seven non-targets in a circular array. Accurate saccades with short latencies were common but errors sometimes occurred and search for an “oddity” target, defined exclusively by difference in colour from a homogeneous set of distractors, was particularly error prone. In Experiment 3, occasional trials contained double targets. First saccades sometimes landed at an intermediate position between the targets. In Experiments 4 and 5, targets were presented with 15 distractors in two concentric rings of 8. Targets specified by shape could be located accurately with a single saccade. Search for a colour-shape conjunction was more difficult but targets in the inner ring were located frequency with a single saccade. The results suggest that the control of the initial eye movement during both simple and conjunction searches is through a spatially parallel process. © 1997 Elsevier Science Ltd. All rights reserve