Cognitive processes in program comprehension

Reviewer: Woodrow Barfield

This paper reports on a protocol analysis study designed to investigate cognitive processes that relate to program understanding. The study attempts to examine cognitive processes that occur over seconds and minutes in order to investigate the understanding of specific lines of code. Six programmers (four experts and two junior-level programmers) with between 3 and 30 years of professional programming experience were asked to “think out loud” as they modified a 250-line FORTRAN program. The verbal transcripts of the protocols were analyzed for their content so that a cognitive model of program understanding could be developed. Based on the protocol analysis, questions, conjectures, and searches are grouped into a higher-order structure called an inquiry. Further, a cognitive model of program understanding is presented based on three major components: a knowledge base, a mental model, and an assimilation process. Discussion of these aspects of programming performance is aimed at developing a computational mechanism to generate the observed programming performance. The paper represents a standard technique used to analyze the thought processes of an individual programmer and provides interesting theoretical information on the development of a cognitive model for program understanding. In future studies to explore specific aspects of the model presented, however, empirical techniques should be used. Other measures of performance, such as program comprehension for specific tasks, should also be employed to allow a broader understanding of the richness of programming performance.