Impaired associative learning in chronic schizophrenics and their first-degree relatives: A study of latent inhibition and the Kamin blocking effect

The performance of chronic schizophrenic probands (n = 21), their first-deg ree schizotypal (22) and non-schizotypal (19) relatives, and normal control s (24), was measured in two associative learning paradigms, latent inhibiti on and the Kamin blocking effect. These paradigms assess the effects on lea rning of initial exposure to other learning contingencies. The normal subje cts showed latent inhibition (retarded learning of an association between a burst of white noise and a visually displayed counter increment, if the su bject had first been pre-exposed to the white noise without any other conse quence) and Kamin blocking (retarded learning of an association between two visual stimuli, if the conditioned stimulus was presented simultaneously w ith a second, already conditioned stimulus). The schizophrenic probands and both the schizotypal and non-schizotypal relatives were severely impaired in basic associative learning, performing much worse than the normal subjec ts in the control conditions (i.e. those lacking stimulus pre-exposure of a ny kind) of both the latent inhibition and the Kamin paradigms and also sho wed a loss of the normal latent inhibition and Kamin blocking effects. The performance of the three clinically defined groups was statisitically indis tinguishable. These findings contrast with previous reports of the performa nce of normal subjects classified as schizotypal by questionnaire, who are not impaired in basic associative learning, and are particularly fast to le arn after stimulus pre-exposure. The results question the assumption that h igh schizotypy, as assessed by questionnaire, is like schizotypy in schizop hrenic kin. The severe impairment in basic associative learning in schizoph renic patients and their kin warrants further investigation (C) 2001 Elsevi er Science B.V. All rights reserved.