Proceedings of the Annual Meeting of the Cognitive Science Society

In many domains, novices exhibit a bias in the direction in which they reason about problems. Earlier studies of LISP programmers using a graphical representation suggested that novice LISP programmers tend to reason forward, working from initial input data toward the goal. W e examined novice programmers learning LISP using the GIL programming tutor and manipulated the direction subjects were allowed to reason (forward, backward, or free). Subjects who were required to work backwards (from goal toward givens) exhibited more difficulty solving the problems than subjects working forward or subjects left free to chose their direction. Backward subjects required more time to solve problems, made more errors, and required more time to plan each solution. W e suggest that these effects and preferences occur because forward reasoning is more congruent with the way novices reason about computer programs, resulting in an increased working memory load for subjects required to work backward.