Tower-Noticing Triggers Strategy-Change in the Tower of Hanoi: A Soar Model
Dirk Ruiz, Allen Newell · 1989
People who solve the Tower of Hanoi stait out with a guided trial-and-error strategy and later acquire recursive strategy, the generally most effective strategy.Protocol data shows that noticing and using subtowers in problem-solving differentiates two subjects who acquired the recursive strategy from one who did not.A working SoiU" model explains Tower of Hanoi strategy-acquisition by first assuming the basic ability to notice and use sublowers, ;uk1 llien charting the process by which this new knowledge is integrated with existing knowledge to produce the recursive strategy.Of particular importance in the integration is learning to see nested subtowers and using simple spatial-miuiipulation reasoning to figure out how to move those subtowers.T\\e model shows a good qualitative fit to the data, providing support for Soar as a unified theory of human cognition. THE PHENOMENONHow are new problem-solving strategies acquired?In particular, what new information triggers the acquisition process, and how is that uifomiation integrated into problem-solving to produce a new strategy?We address Uiis question within the Tower of Hanoi domain.The puzzle (Figure 1) consists of five disks of graded sizes which in the initial state are sitting on one peg (the Source) to form a tower.The object is to move the disks to the Destination peg while moving only one disk at a time from peg to peg and never placing a larger disk on a smaller.Much is already known about this problem.In particular, it