Susan Wiedenbeck

A comparison of the comprehension of object-oriented and procedural programs by novice programmers

Abstract This paper reports on two experiments comparing mental representations and program comprehension by novices in the object-oriented and procedural styles. The subjects were novice programmers enrolled in a second course in programming which taught either the object-oriented or the procedural paradigm. The first experiment compared the mental representations and comprehension of short programs written in the procedural and object-oriented styles. The second experiment extended the study to a larger program incorporating more advanced language features. For the short programs there was no significant difference between the two groups with respect to the total number of questions answered correctly, but the object-oriented subjects were superior to the procedural subjects at answering questions about program function. This suggests that function information was more readily available in their mental representations of the programs and supports an argument that the object-oriented notation highlights function at the level of the individual class. For the long program a corresponding effect was not found. The comprehension of procedural subjects was superior to object-oriented subjects on all types of question. The difficulties experienced by the object-oriented subjects in answering questions in a larger program suggest that they faced problems in marshaling information and drawing inferences from it. We suggest that this result may be related to a longer learning curve for novices of the object-oriented style, as well as to features of the OO style and the particular OO language notation.

Development and Validation of Scores on a Computer Programming Self-Efficacy Scale and Group Analyses of Novice Programmer Self-Efficacy

Self-efficacy theory was applied to the domain of computer programming to develop a thirty-two-item self-efficacy scale for computer programming, primed to the C++ programming language. To assess its construct validity, the scale was administered to 421 students enrolled in an introductory course in C++ programming at the beginning and the end of the course. The reliability of the scores was high. An exploratory factor analysis, with oblimin rotation, yielded a four-factor solution. There was a growth in self-efficacy between two administrations of the scale twelve weeks apart, particularly for students who initially had low self-efficacy. The computer programming self-efficacy of males and females did not differ substantially in practical terms.

Novice/expert differences in programming skills

Automation is the ability to perform a very well-practised task rapidly, smoothly and correctly, with little allocation of attention. This paper resports on experiments which sought evidence of automation in two programming subtasks, recognition of syntactic errors and understanding of the structure and function of simple stereotyped code segments. Novice and expert programmers made a series of timed decisions about short, textbook-type program segments. It was found that, in spite of the simplicity of the materials, experts were significantly faster and more accurate than novices. This supports the idea that experts automate some simple subcomponents of the programming task. This automation has potential implications for the teaching of programming, the evaluation of programmers, and programming language design.

What do novices learn during program comprehension

Comprehension of computer programs involves identifying important program parts and inferring relationships between them. The ability to comprehend a computer program is a skill that begins its development in the novice programmer and reaches maturity in the expert programmer. This research examined the beginning of this process, that of comprehension of computer programs by novice programmers. The mental representations of the program text that novices form, which indicate the comprehension strategies being used, were examined. In the first study, 80 novice programmers were tested on their comprehension of short program segments. The results suggested that novices form detailed, concrete mental representations of the program text, supporting work that has previously been done with novice comprehension. Their mental representations were primarily procedural in nature, with little or no modeling using real‐world referents. In a second study, the upper and lower quartile comprehenders from Study 1 were test...

Mental representations of programs by novices and experts

This paper presents five abstract characteristics of the mental representation of computer programs hierarchical structure, explicit mapping of code to goals, foundation on recognition of recurring patterns, connection of knowledge, and grounding in the program text. An experiment is reported in which expert and novice programmers studied a Pascal program for comprehension and then answered a series of questions about it designed to show these characteristics if they existed in the mental representations formed. Evidence for all of the abstract characteristics was found in the mental representations of expert programmers. Novices’ representations generally lacked the characteristics, but there was evidence that they had the beginnings, although poorly developed, of such characteristics.

An empirical study of novice program comprehension in the imperative and object-oriented styles

The objective of this study was to determine whether the mental representation of object-oriented programs differs from imperative programs for novice programmers. In our study novices who had little or no previous programming experience studied and answered questions about three imperative and three object-oriented programs. The questions targeted information categories making up the program model and the domain model representations of the programs. It was found that there was a sharp contrast between the mental representations of the imperative and object-oriented programs. While the comprehension of the imperative programs was better overall than that of the object-oriented programs, the mental representations of the imperative programs focused on program-level knowledge. On the other hand, the mental representations of the objectoriented programs focused more strongly on domain-level knowledge. The results tend to support the view that language notations differ in how well they support the extraction of various kinds of information.

Beacons in computer program comprehension

In programming, beacons are lines of code which serve as typical indicators of a particular structure or operation. This research sought evidence for the existence and use of beacons in comprehension of a sort program. In the first experiment, subjects memorized and later recalled the whole sort program. Experienced programmers, but not novices or intermediates, recalled the beacon lines much better than non-beacon lines. In the second experiment, experienced programmers studied the same program and then were asked to recall several isolated parts of it. They did not know in advance that they would be asked to recall. Subjects recalled the beacon much better than non-beacon parts. They also were more certain that they recalled the beacon correctly. The results of both experiments support the idea that beacons exist as a focal point for study and understanding of programs by experienced programmers.

Mental Representations Constructed by Experts and Novices in Object-Oriented Program Comprehension

Previous studies on program comprehension were carried out largely in the context of procedural languages. Our purpose is to develop and evaluate a cognitive model of object-oriented (00) program understanding. Our model is based on the van Dijk and Kintschs model of text understanding (1983). One key aspect of this theoretical approach is the distinction between two kinds of representation the reader might construct from a text: the textbase and the situation model. On the basis of results of an experiment we have conducted, we evaluate the cognitive validity of this distinction in 00 program understanding. We examine how the construction of these two representations is differentially affected by the programmers expertise and how they evolve differentially over time.

Learning iteration recursion from examples

Recursion is basic to computer science, whether it is conceived of abstractly as a mathematical concept or concretely as a programming technique. Three experiments were carried out on learning iteration and recursion. The first involved learning to compute mathematical functions, such as the factorial, from worked out examples. The results suggest the subjects are quite able to induce a computational procedure for both iterative and recursive functions. Furthermore, prior work with iterative examples does not seem to facilitate subsequent learning of recursive procedures, nor does prior work with recursive examples facilitate subsequent learning of iterative procedures. The second experiment studied the extent to which people trained only with recursive examples are able to transfer their knowledge to compute other similar recursive mathematical functions stated in an abstract form. It turned out that subjects who transferred to abstractly stated problems performed somewhat worse than they had performed previously when given examples. However, they did far better than a control group trained only with an abstract description of recursion. The third experiment involved comprehension of iterative and recursive Pascal programs. Comprehension of the iterative program was not affected by prior experience with the recursive version of the same program. Comprehension of the recursive version was only weakly affected by prior experience with the iterative version.

Hands-on practice in learning to use software: a comparison of exercise, exploration, and combined formats

This research addresses two issues in the domain of computer training (1) whether learners are able to use exploration-based practice methods effectively to learn to use software and (2) whether some minimal computing background is necessary to be successful with minimalist training and exploration practice. An empirical study was carried out to compare exploration, exercises, and a combined format consisting of an exercise followed by exploration. Subjects of both high and low computer experience were included in the study. It was thought that the combined format might lead to superior training outcomes because it would both structure learning through an exercise and allow learners to go beyond the simple procedures in the training manual through exploration. The results showed that the performance of the low-experience subjects at test did not differ based on the type of practice. However, high-experience subjects who were trained using exercises or the combined format did significantly better than those trained using exploration alone. The similarity of performance of subjects in the exercise and combined practice conditions suggests that the exercise component of the practice explains their success.