Partial reinforcement and context switch effects in human predictive learning

Abstract

Human participants were trained in a trial-by-trial contingency judgements task in which they had to predict the probability of an outcome (diarrhoea) following different cues (food names) in different contexts (restaurants). Cue P was paired with the outcome on half of the trials (partial reinforcement), while cue C was paired with the outcome on all the trials (continuous reinforcement), both cues in Context A. Test was conducted in both Context A and a different but equally familiar context (B). Context change decreased judgements to C, but not to P (Experiment 1). This effect was found only in the cue trained in the context where a different cue was partially reinforced (Experiment 2). Context switch effects disappeared when different cues received partial reinforcement in both contexts of training (Experiment 3). The implications of these results for an explanation of context switch effects in terms of ambiguity in the meaning of the cues prompting attention to the context (e.g., Bouton, 1997) are discussed.

Keywords:

• Context change
• Human predictive learning
• Partial reinforcement

Acknowledgments

This research was financially supported by Junta de Andalucía, Spain, Research Grant HUM642, and by the Spanish Ministerio de Educación y Ciencia and FEDER funds (SEJ2007–67053PSIC). Portions of these data were presented at the Seventeenth Congress of the Spanish Society for Comparative Psychology, Madrid, Spain (September, 2005).