A RANDOM-WALK SIMULATION-MODEL OF MULTIPLE-PATTERN LEARNING IN A RADIAL-ARM MAZE

Wathen and Roberts (1994) reported rather surprising results of a radi al maze study that on any interpretation requires postulation of previ ously unsuspected high-level cognitive processes in rats. In each of f our arms of the eight-arm radial maze, a different serial pattern unfo lded over trials; for example, in one of the arms reward and nonreward alternated over successive trials. On each trial, rats came to track successfully four different patterns simultaneously. The authors sugge sted that rats tracked the pattern by using some form of trial-number strategy; that is, the trial number indicated which arms contained the better rewards. This strategy could involve a hypothesis, considered unlikely by some, that rats are capable of keeping track of as many as eight successive events-as, for example, by counting. A simulation mo del that embodies a specific form of the trial-number hypothesis is de scribed here, and the results of the simulation correlate remarkably w ell with the observed data. In addition, the model makes four separate predictions that are supported by Wathen and Roberts's data and that seem beyond the scope of other available theories.