NOVICES DEBUGGING WHEN PROGRAMMING IN PASCAL

In this study an analysis was made of novices debugging their own Pascal programs. Eight novices verbalized their thoughts aloud while attempting to solve a programming task. Novices' debugging is seen as taking place in negative evaluation episodes (henceforth: evaluation episodes). During the three hour programming session, the novices spent 51% of the time in evaluation episodes. This percentage would presumably have been higher if the subjects had been given more time for the session. Evaluation episodes were found to be triggered in four different contexts: Reaction to an error message (67% of the total time spent in any evaluation episode), Reaction to the resulting value of a test run (23%), Hint from the experimenter (4%) and Other (6%). When related to results presented by Gray and Anderson (1987), our results indicate that novices perform the substantial part of their debugging after they have compiled the program, or part of it, for the first time. Despite the information given in the computer's error messages, the percentage of errors eliminated in episodes triggered by such messages was not higher than could be expected from the time spent in these episodes. Our results indicate that the importance of activity oriented towards understanding one's program during debugging depends on: (1) whether the error elicits an error message from the computer or not; and (2) the general programming strategy used by the subject. © 1990 Academic Press Limited.