SIZE ESTIMATION IN PARANOID AND NONPARANOID SCHIZOPHRENICS

Abstract

Paranoid (15) and nonparanoid (15) schizophrenics and normal controls (15) were administered a size estimation task featuring 2 administrations of nonthematic standard stimuli. The standard stimuli were presented under 3 conditions of background stimuli: surrounded by 4 smaller stimuli of the same kind; surrounded by 4 larger stimuli of the same kind; and presented without background stimuli. Standard stimuli were presented at exposure times of 33 and 4000 ms. On the 1st administration, nonparanoid schizophrenics overestimated size relative to paranoid schizophrenics with normal controls intermediate in performance between the paranoid schizophrenics and nonparanoid schizophrenics, particularly on longer stimulus exposure times. The groups did not differ on the 2nd administration. The repeated administration of size estimation procedures in which the effects of sequence and thematic content stimuli were inextricably confounded may have contributed to recent conflicting findings in the size estimation literature. Contrary to predictions generated by Cromwell''s stimulus redundancy formulation, the paranoid schizophrenics were not more affected by the size of the background stimuli than the nonparanoid schizophrenics.