Confirmation bias

Confirmation bias is a phenomenon where people tend to favor information that confirms their existing beliefs or hypotheses, often disregarding conflicting evidence. This cognitive bias is present in various aspects of life, including design and user experience development.

It can lead designers to misinterpret the reasons behind user behavior or product performance issues. For example, suppose a designer is convinced that a website's performance issue is due to its slow loading speed. They might focus solely on optimizing images and scripts, interpreting any slight improvements in speed as confirmation that they were correct.

However, the real issue might be poor navigation design, which isn't addressed because the designer was focused on load times. This oversight can prevent the real problem from being resolved, affecting the user experience negatively.