Proceedings of the Annual Meeting of the Cognitive Science Society

The construction and retrieval of plan schemas was studied using a programming task. Novice programmers were asked to write programs and their problem solving strategies analysed from the manner in which they expanded a program goal. Four programs were used in the study, comprising two sets of problem isomorphs. These isomorphs required the same programming plans for solution, but differed in their cover stories. Plan development withm a prob em solving episode and across episodes was thus easily tracked. Development of a plan to achieve a problem goal showed a focus of attention on the current goal to the exclusion of concerns about other parts of the program. A solution was not found by a process of reasoning and top-down design. Rather, one goal was selected for expansion and in the process of this expansion new goals were discovered and solved to the extent required by the current context. The program was built up from solving individual goals, not down from the problem specification. The development of plans to achieve three of these goals, the selection, simple (non-looping) sum and read loop goals, is discussed in some detail to show the relation between problem solving and schema formation. Evidence of top-down design using schemas appeared only late in the study, suggesting that its use in teaching should be delayed until the novice can 'speak the language' of schema retrieval.