Blind Spot Bias is the tendency to see oneself as less biased than other people, or to be able to identify more cognitive biases in others than in oneself.
According to Wikipedia bias blind spots may be caused by a variety of other biases and self-deceptions.
Self-enhancement biases may play a role, in that people are motivated to view themselves in a positive light. Biases are generally seen as undesirable, so people tend to think of their own perceptions and judgments as being rational, accurate, and free of bias. The self-enhancement bias also applies when analyzing our own decisions, in that people are likely to think of themselves as better decision makers than others.
People also tend to believe they are aware of "how" and "why" they make their decisions, and therefore conclude that bias did not play a role. Many of our decisions are formed from biases and cognitive shortcuts, which are unconscious processes. By definition, people are unaware of unconscious processes, and therefore cannot see their influence in the decision making process.
When made aware of various biases acting on our perception, decisions, or judgments, research has shown that we are still unable to control them. This contributes to the bias blind spot in that even if one is told that they are biased, they are unable to alter their biased perception.