The effect of mode of presentation on Tower of Hanoi problem solving

The Tower of Hanoi (TOH) is a classic problem that can be solved via multiple strategies. This study used TOH to examine how mode of presentation of a problem influences strategy use and transfer. Undergraduate students (Experiment 1) or Prolific workers (Experiment 2) completed two TOH problems of varying difficulty (4-disk/5-disk). They were randomly assigned to different conditions in which problems were either high in internal representation (mental) or high in external representation (computer). Participants were better able to complete problems successfully when external representations were available but completed problems in fewer moves when relying on internal representations. In addition, participants spent more time between moves when solving problems mentally, suggesting that external representations encourage speed while internal representations promote accuracy when solving recursion problems. Lastly, both experiments provide evidence that first solving a problem mentally encouraged participants to use strategies similar to goal recursion on a second problem.