Attentional Scanpath on the Span of Apprehension Task in Paranoid Schizophrenia

The Span of Apprehension task represents a putative cognitive vulnerability marker for schizophrenia. To investigate the nature of the scanning deficits on the Span of Apprehension shown by patients with paranoid schizophrenia a wide visual angle partial report version of the task was administered to 18 paranoid schizophrenics and 18 normal controls. An analysis of scan paths, based upon target detection rates as a function of target location, suggests that patients with paranoid schizophrenia use a similar path and number of covert scan moves in iconic memory as do normal controls. Some evidence was found for an impairment related to the speed of processing information in iconic memory. Paranoid schizophrenics appear to suffer from a delay in the initiation of covert search, but not from an impairment in discrete computational functions (i.e. disengage, move and engage functions). Once search is initiated it seems to be carried out as efficiently as in normal controls (German J Psychiatry 1998; 1: 1-5).