This study tested the hypotheses that visual search impairments in schizophrenia are due to a delay in initiation of search or a slow rate of serial search. We determined the specificity of these impairments by comparing children with schizophrenia to children with attention-deficit hyperactivity disorder (ADHD) and age-matched normal children. The hypotheses were tested within the framework of feature integration theory by administering children tasks tapping parallel and serial search. Search rate was estimated from the slope of the search functions, and duration of the initial stages of search from time to make the first saccade on each trial. As expected, manual response times were elevated in both clinical groups. Contrary to expectation, ADHD, but not schizophrenic, children were delayed in initiation of serial search. Finally, both groups showed a clear dissociation between intact parallel search rates and slowed serial search rates.
Bibliographical noteFunding Information:
We would like to thank the parents and the children who participated in the study. This study was included in the doctoral dissertation of the first author. We are grateful to members of the dissertation committee (Jackson Beatty, Ph.D., Thomas Wickens, Ph.D., and Cindy Yee-Bradburry, Ph.D.) and two anonymous reviewers, who made constructive suggestions that improved the manuscript. We also thank Patrick Carlyle for writing the computer programs for presenting and analyzing the data. This research was supported in part by grants to Robert F. Asarnow, Ph.D., from the National Institute of Mental Health (MH 45112), the Stanley Foundation, and the Delia Martin Foundation. Dr. Karatekin was supported by the Delia Martin Foundation in writing this manuscript.
Copyright 2007 Elsevier B.V., All rights reserved.
- Attention-deficit hyperactivity disorder (ADHD)
- Parallel and serial search
- Saccadic eye movements
- Visual-spatial attention