Negative priming in schizophrenia: effects of masking and prime presentation time

Beech et al. [Br. J. Clin. Psychol. 28 (1989) 109--116] previously reported attenuated negative priming in schizophrenic patients that was interpreted as a sign of dysfunctional cognitive inhibition. However, subsequent research has provided mixed results. In the present study, it was investigated whether reduced negative priming in schizophrenics may be an experimental artifact. Based on evidence from backward masking studies in schizophrenia, it was hypothesized that brief prime presentation times and pattern masking as used by Beech et al. and others may have impaired the visual perception of the prime display in schizophrenics. 20 schizophrenic patients and 20 matched healthy controls participated in the study. Subjects completed four negative priming experiments varying in prime presentation time (100 or 250 ms) and masking (a mask or a blank screen followed prime presentation). In line with prediction, reduced negative priming in schizophrenics only occurred for trials with 100 ms prime presentation time followed by a mask. Neither psychopathology nor any sociodemographic variable correlated substantially with negative priming. Results strongly suggest that reduced negative priming in schizophrenics may not be due to reduced cognitive inhibition but mirrors perceptual deficits.