T. Suslow et V. Arolt, BACKWARD-MASKING IN SCHIZOPHRENIA - TIME-COURSE OF VISUAL PROCESSING DEFICITS DURING TASK-PERFORMANCE, Schizophrenia research, 33(1-2), 1998, pp. 79-86
Backward masking deficits have been put forward as potential psycholog
ical markers for vulnerability to schizophrenia. This study was conduc
ted to investigate whether schizophrenic patients improve their perfor
mance on a backward masking task during a single test session. The abi
lity of a degraded stimulus version of the masking task to act as a sp
ecific diagnostic marker for paranoid schizophrenia (versus affective
disorder) was also investigated. The backward masking task was perform
ed on 18 paranoid schizophrenic patients, 18 unipolar depressed patien
ts, and 18 non-psychiatric controls. Paranoid schizophrenic patients w
ere included because they tend to show normal performance with traditi
onal masking protocols. Schizophrenic patients made significantly more
detection errors compared to depressives and non-psychiatric controls
where interstimulus intervals (ISIs) longer than 14 ms were used. Unl
ike depressed patients and non-psychiatric controls, schizophrenic pat
ients showed no reduction in error rate during the entire period over
which the backward masking task was performed. The constant error rate
which was observed at an ISI of 114 ms suggests that schizophrenic pa
tients cannot attenuate the disruption effect due to deflection of att
ention from the target to the mask. The backward masking deficit in sc
hizophrenia appears to arise from a temporarily stable visual processi
ng impairment in performance within a single test session. (C) 1998 El
sevier Science B.V. All rights reserved.