Impaired temporal inhibition of irrelevant processing in patients with schizophrenia: evidence from attentional blink, visual backward masking, and attentional modulation of prepulse inhibition

Abstract

METHODS: The expression of attentional blink (AB) in schizophrenic patients (n = 23) was compared to healthy subjects (n = 24) in a dual-target rapid serial visual presentation (RSVP) paradigm in which a sequence of discrete stimuli was presented in rapid succession. Target identification accuracy was then correlated with performances in a visual backward masking (VBM) task and measures of prepulse inhibition (PPI). In the VBM task, subjects were required to name a letter which was masked at SOAs 16– 83 ms. Prepulse inhibition (PPI) of acoustic startle response was measured for prepulse – pulse intervals of 60 and 120 ms. To investigate the attentional modulation of PPI, subjects were instructed to count either high- or low-tone prepulse and ignore the other prepulse. RESULTS: Schizophrenic patients showed significant enhancement of AB, greater susceptibility to VBM, and lack of PPI when compared to healthy subjects. The latter two findings may reflect a reduced ability to inhibit transient processing of disruptive stimuli in the patients. Greater AB magnitude in patients was correlated with greater susceptibility to VBM; lower second-target accuracy in the AB task was correlated with weaker PPI in the ignored prepulse (120 ms) condition. In the controls, AB magnitude correlated negatively with VBM susceptibility; first-target accuracy in the AB task correlated negatively with the PPI in the attended prepulse (60 ms) condition. CONCLUSION: This pattern of results suggests that enhancement of the AB effect in patients with Schizophrenia may be due to a deficit in the inhibition of irrelevant information processing.