Proceedings of the Annual Meeting of the Cognitive Science Society

Isomorphic problems are to cognition what optical illusions are to perception. By drawing attention to anomalies such as problems which are identical in form but vary widely in difficulty they highlight cognitive processes normally hid- den a m o n g the minutiae of our theories. Results are reported from an experiment in which sub- jects solved a three disk Tower of Hanoi problem and its Monster Globe change isomorph using direct manipulation tableaus or paper and pencil. Subjects using direct manipulation were found to solve the Monster Globe problem in half the time taken by paper and pencil subjects. A n explana- tion revolving around attunement to environmen- tal constraints is advanced to account for this difference.