It has been well documented that a large portion of the cost of any software lies in the time spent by developers in understanding a program’s source code before any changes can be undertaken. One of the main contributors to software comprehension, by subsequent developers or by the authors themselves, has to do with the quality of the lexicon, (i.e., the identifiers and comments) that is used by developers to embed domain concepts and to communicate with their teammates. In fact, previous research shows that there is a positive correlation between the quality of identifiers and the quality of a software project. Results suggest that poor quality lexicon impairs program comprehension and consequently increases the effort that developers must spend to maintain the software. However, we do not yet know or have any empirical evidence, of the relationship between the quality of the lexicon and the cognitive load that developers experience when trying to understand a piece of software. Given the associated costs, there is a critical need to empirically characterize the impact of the quality of the lexicon on developers’ ability to comprehend a program.
In this study, we explore the effect of poor source code lexicon and readability on developers’ cognitive load as measured by a cutting-edge and minimally invasive functional brain imaging technique called functional Near Infrared Spectroscopy (fNIRS). Additionally, while developers perform software comprehension tasks, we map cognitive load data to source code identifiers using an eye tracking device. Our results show that the presence of linguistic antipatterns in source code significantly increases the developers’ cognitive load.
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Measuring the impact of lexical and structural inconsistencies on developers’ cognitive load during bug localization
A large portion of the cost of any software lies in the time spent by developers in understanding a program’s source code before any changes can be undertaken. Measuring program comprehension is not a trivial task. In fact, different studies use self-reported and various psycho-physiological measures as proxies. In this research, we propose a methodology using functional Near Infrared Spectroscopy (fNIRS) and eye tracking devices as an objective measure of program comprehension that allows researchers to conduct studies in environments close to real world settings, at identifier level of granularity. We validate our methodology and apply it to study the impact of lexical, structural, and readability issues on developers’ cognitive load during bug localization tasks. Our study involves 25 undergraduate and graduate students and 21 metrics. Results show that the existence of lexical inconsistencies in the source code significantly increases the cognitive load experienced by participants not only on identifiers involved in the inconsistencies but also throughout the entire code snippet. We did not find statistical evidence that structural inconsistencies increase the average cognitive load that participants experience, however, both types of inconsistencies result in lower performance in terms of time and success rate. Finally, we observe that self-reported task difficulty, cognitive load, and fixation duration do not correlate and appear to be measuring different aspects of task difficulty.
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- Award ID(s):
- 1755995
- NSF-PAR ID:
- 10135165
- Date Published:
- Journal Name:
- Empirical Software Engineering
- ISSN:
- 1382-3256
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Source code is a form of human communication, albeit one where the information shared between the programmers reading and writing the code is constrained by the requirement that the code executes correctly. Programming languages are more syntactically constrained than natural languages, but they are also very expressive, allowing a great many different ways to express even very simple computations. Still, code written by developers is highly predictable, and many programming tools have taken advantage of this phenomenon, relying on language model
surprisal as a guiding mechanism. While surprisal has been validated as a measure of cognitive load in natural language, its relation to human cognitive processes in code is still poorly understood. In this paper, we explore the relationship between surprisal and programmer preference at a small granularity—do programmers prefer more predictable expressions in code? Usingmeaning‐preserving transformations , we produce equivalent alternatives to developer‐written code expressions and run a corpus study on Java and Python projects. In general, language models rate the code expressions developerschoose to write as more predictable than these transformed alternatives. Then, we perform two human subject studies asking participants to choose between two equivalent snippets of Java code with different surprisal scores (one original and transformed). We find that programmersdo prefer more predictable variants, and that stronger language models like the transformer align more often and more consistently with these preferences.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s10664-019-09751-4
