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.