  Cognitive biases appear during code review. They significantly impact the
creation of feedback and how it is interpreted by developers. These biases can
lead to illogical reasoning and decision-making, violating one of the main
hypotheses supporting code review: developers' accurate and objective code
evaluation. This paper explores harmful cases caused by cognitive biases during
code review and potential solutions to avoid such cases or mitigate their
effects. In particular, we design several prototypes covering confirmation bias
and decision fatigue. We rely on a developer-centered design approach by
conducting usability tests and validating the prototype with a user experience
questionnaire (UEQ) and participants' feedback. We show that some techniques
could be implemented in existing code review tools as they are well accepted by
reviewers and help prevent behavior detrimental to code review. This work
provides a solid first approach to treating cognitive bias in code review.
