A process model for Missionaries-Cannibals and other river-crossing problems

We extend a model originally developed by Atwood and Polson (1976) for the water jug task to four isomorphs of the Missionaries-Cannibals problem. Our results show that variation in cover story produced no differences in number of legal moves to solution, but caused large differences in illegal moves. A three-stage process model incorporating means-ends heuristics, assumptions about the utilization of memory, and an illegal move-detection process is able to account for both legal and illegal move data from all four versions of the problem.