Surface and Edge Information for Spatial Integration: A Saccadic-selection Search Task

Abstract

Three experiments are described that investigate visual integration across space using a saccade selection paradigm. Subjects saccaded to a vertical target in the presence of a number of horizontal distractor items. Both horizontal and vertical items were composed of two identical elements, so, in order to locate the target, subjects had to integrate the pairs of elements together. We measured saccade accuracy, the proportion of saccades directed to the vertical target, together with saccade latency following display appearance. In Experiment 1 we found that saccade accuracy was improved by the items having either common surface properties or collinear edges. These effects were not a resultof increased display heterogeneity (Experiment 2), or a result of the introduction of a strong internal contour between the items (Experiment 3). These results show that for saccadic selection both surface and edge properties of items are processed. This in turn suggests thatearly visual processing encodes and exploits both types of information.