Differential Impairment of Positive and Negative Schizotypy in List-Method and Item-Method Directed Forgetting

Schizophrenia is characterized by cognitive impairment and this impairment is expected to occur, albeit to a lesser degree, in people putatively at risk for schizophrenia. Two experiments assessed the relationship between directed forgetting (DF) and schizotypy, which is a multidimensional construct that reflects the expression of the underlying vulnerability for schizophrenia. Experiment 1 involved item-method DF and Experiment 2 involves list-method DF study. The schizotypy dimensions exhibited differential patterns of impairment across the 2 methods that suggest different underlying processes. Positive schizotypy showed impairment in item-method DF that was driven by reduced ability to forget forget-cued items, whereas performance on remember-cued items was unaffected in positive schizotypy. Despite the deficit in item-method DF, positive schizotypy participants showed preserved performance in list-method DF. The opposite pattern was found in negative schizotypy participants, who showed impairment in list-method DF, despite preserved performance in item-method DF. Negative schizotypy was previously associated with deficits in context processing and, consistent with context-change account of list-method DF, showed deficits in list-method DF task. Positive schizotypy is characterized by deficits in inhibitory control and, consistent with inhibitory account of item-method DF, showed deficits in item-method DF task. Collectively, these results (a) suggest that different DF methods involve different underlying mechanisms, (b) support the context-account of list-method DF and an inhibitory account of item-method DF, and (c) support the multidimensional model of schizotypy by showing differential impairment in positive and negative schizotypy across the 2 DF tasks.