Background: Despite advances in the pharmacologic treatment of schizophreni
a, the neurophysiologic mechanism(s) of disordered attention in schizophren
ia remain elusive. Objective: The goal of the present study was to assess s
pecific components of attention, including disengagement, movement, re-enga
gement, and the inhibitory processes involved their control. Methods: Thirt
een chronic schizophrenics from the inpatient and outpatient units of the V
eterans Administration Medical Center (New Orleans, LA) and thirteen normal
control subjects were administered a saccadic eye movements task. Saccade
latency was measured in the presence of contra-lateral distracter stimuli t
hat preceded the target onset (Distracter-before), followed the target onse
t (Distracter - after) or in the absence of a distracter (No-distracter). I
n order to assess the interactive process of fixation disengagement and tar
get selection, fixation was either offset before the target (Gap) or it rem
ained on in the presence of the target (Overlap). Results: Repeated measure
s analysis of variance revealed that saccadic latency in patients with schi
zophrenia is prolonged to a greater extent than in normal control subjects
in the presence of distracter stimuli. Patients with schizophrenia are also
characterized by a greater percentage of error saccades directed to the di
stracter, and require a longer latency to "issue" corrective saccades follo
wing error saccades. Conclusions: The findings suggest that patients with s
chizophrenia are required to invoke volitional control under distracter con
ditions, whereas normal control subjects require minimal volitional control
. The results are interpreted in terms of the inhibitory mechanisms that re
gulate attention.