Latent inhibition, learned irrelevance, and schizotypy: assessing their relationship.

INTRODUCTION: Previous research suggests that latent inhibition is reduced in patients with acute schizophrenia and in healthy participants with high levels of schizotypic characteristics. Other evidence indicates the disruption of a related effect (learned irrelevance) in patients with acute schizophrenia.
METHOD: This study used a recently developed latent inhibition procedure, that avoids methodological limitations of previous studies, and a related learned irrelevance procedure to assess the relationship between these phenomena and schizotypic characteristics in undergraduate participants.
RESULTS: Participants preexposed to a letter (S) learnt the predictive relationship between that letter and another letter (X) slower than the relationship between a novel letter and X (a latent inhibition effect). Experiment 1 found reduced latent inhibition in the high schizotypy group after 10, but not 20 preexposures. In Experiment 2, participants preexposed to both S and X learnt a subsequent relationship between them slower than the relationship between a novel letter and X (a learned irrelevance effect). This effect was abolished in participants with high levels of schizotypy.
CONCLUSIONS: These results are both the first demonstration of abolished learned irrelevance and of a significant reduction in latent inhibition without employing an explicit masking task in participants with high levels of positive schizotypy.