SACCADE TARGET SELECTION AND OBJECT RECOGNITION - EVIDENCE FOR A COMMON ATTENTIONAL MECHANISM

The spatial interaction of visual attention and saccadic eye movements was investigated in a dual-task paradigm that required a target-direc ted saccade in combination with a letter discrimination task Subjects had to saccade to locations within horizontal letter strings left and right of a central fixation cross. The performance in discriminating b etween the symbols ''E'' and reverse E'', presented tachistoscopically before the saccade within the surrounding distracters was taken as a measure of visual attention, The data show that visual discrimination is best when discrimination stimulus and saccade target refer to the s ame object; discrimination at neighboring items is close to chance lev el. Also, it is not possible, in spite of prior knowledge of discrimin ation target position, to direct attention to the discrimination targe t while saccading to a spatially close saccade target. The data strong ly argue for an obligatory and selective coupling of saccade programmi ng and visual attention to one common target object, The results favor a model in which a single attentional mechanism selects objects for p erceptual processing and recognition, and also provides the informatio n necessary for motor action. Copyright (C) 1996 Elsevier Science Ltd.