Primers or Reminders? The Effects of Existing Review Comments on Code Review
In contemporary code review, the comments put by reviewers on a specific code change are immediately visible to the other reviewers involved. May this visibility prime new reviewers’ attention (due to the human’s proneness to availability bias), thus biasing the code review outcome? In this study, we investigate this topic by conducting a controlled experiment with 85 developers who perform a code review and a psychological experiment. Although ~70% of participants are assessed to be prone to availability bias, we did not observe a biasing effect due to the existing review comments. Only when reviewers are primed by a comment on a bug that normally is not considered in code review, they are more likely to find another occurrence of this type of bug. Moreover, this priming effect does not influence reviewers’ likelihood of detecting other types of bugs. Our findings suggest that the current code review practice is effective because existing review comments about bugs in code changes are not negative primers, rather positive reminders for bugs that would otherwise be overlooked during code review.