Attentional guidance during visual search among patients with schizophrenia

Abstract

The current study investigated visual guidance and saccadic selectivity during visual search among patients with schizophrenia (SCZ). Data from a previous study (Elahipanah, A., Christensen, B.K., & Reingold, E.M., 2008. Visual selective attention among persons with schizophrenia: The distractor ratio effect. Schizophr. Res. 105, 61–67.) suggested that visual guidance for the less frequent distractors in a conjunction search display (i.e., the distractor ratio effect) is intact among SCZ patients. The current study investigated the distractor ratio effect among SCZ patients when: 1) search is more demanding, and 2) search involves motion perception. In addition, eye tracking was employed to directly study saccadic selectivity for the different types of distractors. Twenty-eight SCZ patients receiving a single antipsychotic medication and 26 healthy control participants performed two conjunction search tasks: a within-dimension (i.e., colour × colour) search task; and a cross-dimension (i.e., motion × colour) search task. In each task the relative frequency of distractors was manipulated across 5 levels. Despite slower search times, patients' eye movement data indicated unimpaired visual guidance in both tasks. However, in the motion × colour conjunction search task, patients displayed disproportionate difficulty detecting the moving target when the majority of distractors were also moving. Results demonstrate that bottom–up attentional guidance is unimpaired among patients with SCZ; however, patients' impairment in motion discrimination impedes their ability to detect a moving target against noisy backgrounds.