Acquisition of discriminations involving ambiguous or non-ambiguous features: an evaluation of two configural learning models

The present rat experiment evaluated the validity of two formal accounts of configural learning in the framework of discrimination tasks involving the serial presentation of feature and target stimuli: Rescorla's (1973) modif ication of the Rescorla-Wagner model (1972) and the Pearce model (1987). Th e first, ambiguous: feature task was of the form X -->A+, Y -->A-, X -->B-, Y -->B+, in which X and Y represent visual features, '-->' signifies a ser ial arrangement, A and B are auditory target stimuli, and '+' and '-' symbo lise food-reinforcement and non-reinforcement, respectively. The second, no n-ambiguous feature task was of the form: X -->A+, Y -->A-, X -->B, Y -->B- . The former task was much more difficult to solve than was the latter task . The Rescorla model is able to account for the observed differences betwee n the two tasks in learning rates and in the associative strength of featur e X with more plausible parameter values than is the Pearce model. It is su ggested that models acknowledging a role for both elemental and configural learning can better account for discrimination learning in discrimination t asks of the sort presented in this study than do models that exclusively al low for configural learning. (C) 2001 Elsevier Science B.V. All rights rese rved.