A “random-walk” simulation model of multiple-pattern learning in a radial-arm maze

Wathen and Roberts (1994) reported rather surprising results of a radial maze study that on any interpretation requires postulation of previously unsuspected high-level cognitive processes in rats. In each of four arms of the eight-arm radial maze, a different serial pattern unfolded 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 suggested 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 model that embodies a specific form of the trial-number hypothesis is described here, and the results of the simulation correlate remarkably well 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.