OBJECTIVE: Schizophrenic patients have repeatedly demonstrated the
inability to rapidly process information when tasks are timed or the
processing load is relatively high. Schizophrenic patients show consistent
deficits in the visual backward masking paradigm. In visual backward
masking, an informational target stimulus is presented, followed after an
interstimulus interval by a masking stimulus that interferes with or
interrupts target identification. METHOD: In order to clarify whether the
visual backward masking deficits of schizophrenic patients are indeed
central rather than peripheral in origin, the authors compared visual
backward masking to psychometrically matched visual forward masking
performance in 35 normal comparison subjects and then 35 schizophrenic
patients. In visual forward masking, the mask precedes the target, and
visual forward masking mechanisms are felt to be more peripheral (retinal)
than are visual backward masking mechanisms. RESULTS: For psychometrically
matched forward and backward masking tasks, the schizophrenic patients had
a selective and differential deficit in the backward masking condition.
CONCLUSIONS: These results support the interpretation that the observed
visual backward masking deficits of schizophrenic patients are centrally
mediated.Abstract Teaser