Variations in selective and nonselective prediction error with the negative dimension of schizotypy

Abstract

Two human associative-learning experiments investigated the relationship between the negative dimension of schizotypy and selective and nonselective prediction-error learning. Experiment 1 demonstrates that individuals low, but not high, on the introvertive anhedonia dimension of schizotypy demonstrate Kamin blocking, which has been taken to reflect the operation of selective learning (Rescorla & Wagner, 1972). In complement, Experiment 2 demonstrates that individuals high, but not low, on the same dimension demonstrate asymmetrical learning about the components of a compound stimulus that differ in their associative history, which has been suggested to reflect the operation of nonselective learning (Rescorla, 2000). The implications of this double dissociation for understanding the nature of the cognitive deficit in schizophrenia and for theories of learning are considered.

Keywords:

• Kamin blocking
• Schizophrenia
• Schizotypy
• Prediction error
• Introvertive anhedonia
• Negative symptoms

Acknowledgments

This work was supported by a pump-priming grant from the School of Psychology, University of Nottingham. We are grateful to Victoria Ratcliffe for her assistance with the collection of data for Experiment 2, to Mike Le Pelley for useful discussion, and to Paula Moran and Henry Chase for their comments on an earlier draft of this paper.

Notes

¹ Jones, Gray, and Hemsley (1992a) provided a reanalysis of these data. The results indicated a nonsignificant trend towards a relationship between positive schizotypal symptoms and the attenuation of blocking.

² Additionally, the absence of any difference between the high and low groups in their learning curves seems to be at odds with the more general characterization of the core deficit in schizophrenia as a “loosening of associations” (Bleuler, 1911).

³ According to Equation (2), on AB– trials, the prediction error for B will be less than the prediction error for A. It thus follows from Equation (5) that attention (α) will climb to B and fall to A. If α_B becomes sufficiently greater than α_A, the effects of the larger prediction error that A possesses on AB– trials will be undermined and could ultimately lead to responding to AC and BD being equivalent. These ideas are considered in more detail by Le Pelley and McLaren (2001).