Empirical Software Engineering

, Volume 18, Issue 2, pp 219–276 | Cite as

The impact of identifier style on effort and comprehension

  • Dave Binkley
  • Marcia Davis
  • Dawn Lawrie
  • Jonathan I. Maletic
  • Christopher Morrell
  • Bonita Sharif


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.


Program comprehension Text recognition Coding standards Identifier names Memory Identifier styles Eye-tracking study Code readability 



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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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Dave Binkley
    • 1
  • Marcia Davis
    • 3
  • Dawn Lawrie
    • 1
  • Jonathan I. Maletic
    • 4
  • Christopher Morrell
    • 2
  • Bonita Sharif
    • 5
  1. 1.Department of Computer ScienceLoyola University MarylandBaltimoreUSA
  2. 2.Department of Mathematics and StatisticsLoyola University MarylandBaltimoreUSA
  3. 3.Center for Social Organization of SchoolsJohns Hopkins UniversityBaltimoreUSA
  4. 4.Department of Computer ScienceKent State UniversityKentUSA
  5. 5.Department of Computer Science and Information SystemsYoungstown State UniversityYoungstownUSA

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