Which schizotypal dimensions abolish latent inhibition?

OBJECTIVE To evaluate which dimensions of schizotypy are associated with a reduction in latent inhibition (LI), akin to that seen in schizophrenia. DESIGN LI was compared in low and high scorers on the four dimensions of the OLIFE questionnaire (Mason, Claridge, & Jackson, 1995), with the predictions that the unusual experiences and impulsive non-conformity subscales would be associated with loss of LI, while the introvertive anhedonia subscale would not be. METHODS A total of 80 healthy volunteers completed a visual LI task. Half of these participants were pre-exposed to the conditioning stimulus; the others were not. The primary outcome measure was the number of trials taken to learn the task. RESULTS LI was reduced for the dimensions of unusual experiences, impulsive non-conformity and cognitive disorganization. There was no effect of introvertive anhedonia. The effect of unusual experiences and impulsive non-conformity upon LI was mediated via changes in the pre-exposure group and not in the non-pre-exposed group. Conversely, high scorers on the cognitive disorganization scale showed slower learning in non-pre-exposure, but with no effect upon stimulus pre-exposure. As the unusual experiences and implusive non-conformity scales were correlated, we examined if either of these was primary. Analysis showed unusual experiences to be primary, with impulsive non-conformity not contributing significant additional independent variance. CONCLUSIONS Our results support the proposition that the cognitive processes underlying the mediation of LI are related to the genesis of unusual experiences in schizotypy and, by extension, the positive symptoms of schizophrenia.