Visual search irregularities in schizophrenia depend on display size switching

Abstract

Introduction. In past research it has been demonstrated that when performing a visual search task with either one or multiple (4, 7 or 10) stimuli displayed, patients with schizophrenia demonstrate slow response times (RTs) in the display size of one, target‐absent (one‐absent) condition. The goals of the present investigation were to replicate this effect, and to gain an understanding of the underlying cognitive operations by comparing display‐size switch to display‐size repeat trials. Correspondence should be addressed to Dr Todd S. Woodward, Department of Medicine and Research, Room 302, 3rd Floor, Henry Esson Young Building, Riverview Hospital, 2601 Lougheed Highway, Coquitlam, British Columbia, Canada, V3C 4J2; e‐mail: twoodward@psych.ubc.ca This research was supported by a post‐doctoral fellowship from the Canadian Psychiatric Research Foundation, and Canadian Institute for Health Research to TSW, and operating grants from the Dr Norma Calder Schizophrenia Foundation, and the Riverview Hospital Academic Steering Committee to TSW. The authors would like to thank Dr Elton Ngan for providing input on early versions of this manuscript, and Jessica Bristowe, Carrie Cuttler, Luka Janicijevic, Jannine Lasaleta, Allan Lau, Ailin Wu, and Izabella Patyk for assistance with data collection and manuscript preparation. Methods. In two experiments, patients and controls performed a visual search task with either one or four stimuli displayed. In Experiment 1 (one block with mixed switch and repeat trials), RT for display‐size switch trials was compared to RT from display‐size repeat trials. In Experiment 2, the display‐size one and display‐size four conditions were run in separate, homogeneous blocks. Results. The results demonstrate that the one‐absent slowing effect was eliminated on repeat trials, regardless of whether the switch and repeat trials were mixed or presented in separate blocks. Conclusions. This set of results suggests that a combination of cueing and switching effects may underlie the one‐absent slowing observed in patients, such that switching to the one‐absent condition is difficult due to insufficient cueing of the relevant cognitive operations. This visual search paradigm is an excellent candidate for inclusion in the development of a neurocognitive profile specific to schizophrenia.