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The impact of identifier style on effort and comprehension

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Abstract

A family of studies investigating the impact of program identifier style on human comprehension is presented. Two popular identifier styles are examined, namely camel case and underscore. The underlying hypothesis is that identifier style affects the speed and accuracy of comprehending source code. To investigate this hypothesis, five studies were designed and conducted. The first study, which investigates how well humans read identifiers in the two different styles, focuses on low-level readability issues. The remaining four studies build on the first to focus on the semantic implications of identifier style. The studies involve 150 participants with varied demographics from two different universities. A range of experimental methods is used in the studies including timed testing, read aloud, and eye tracking. These methods produce a broad set of measurements and appropriate statistical methods, such as regression models and Generalized Linear Mixed Models (GLMMs), are applied to analyze the results. While unexpected, the results demonstrate that the tasks of reading and comprehending source code is fundamentally different from those of reading and comprehending natural language. Furthermore, as the task becomes similar to reading prose, the results become similar to work on reading natural language text. For more “source focused” tasks, experienced software developers appear to be less affected by identifier style; however, beginners benefit from the use of camel casing with respect to accuracy and effort.

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Notes

  1. The Levenshtein Edit Distance is the minimum number of operations needed to transform one string into another. An operation is an insertion, deletion, or substitution of a single character.

  2. The Performance and Efficiency Hypotheses are restated in terms of the variable used to study it.

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Acknowledgements

Special thanks to all the participants as this work would not be possible without your time. Our thanks to David Robbins for assisting in the use of the Tobii eye tracker and Matt Hearn for helping in the preparation and administration of the studies. Finally, thanks to our three reviewers for their thorough and well considered reviews.

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Authors and Affiliations

  1. Department of Computer Science, Loyola University Maryland, Baltimore, MD, 21210-2699, USA

    Dave Binkley & Dawn Lawrie

  2. Department of Mathematics and Statistics, Loyola University Maryland, Baltimore, MD, 21210-2699, USA

    Christopher Morrell

  3. Center for Social Organization of Schools, Johns Hopkins University, Baltimore, MD, 21218, USA

    Marcia Davis

  4. Department of Computer Science, Kent State University, Kent, OH, 44242, USA

    Jonathan I. Maletic

  5. Department of Computer Science and Information Systems, Youngstown State University, Youngstown, OH, 44555, USA

    Bonita Sharif

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  1. Dave Binkley
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  2. Marcia Davis
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  3. Dawn Lawrie
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  4. Jonathan I. Maletic
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  5. Christopher Morrell
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  6. Bonita Sharif
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Correspondence to Bonita Sharif.

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Editors: Giulio Antoniol and Keith Brian Gallagher

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Binkley, D., Davis, M., Lawrie, D. et al. The impact of identifier style on effort and comprehension. Empir Software Eng 18, 219–276 (2013). https://doi.org/10.1007/s10664-012-9201-4

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