A bias blind spot refers to the human ability for an individual to see and identify how other people are being influenced by outside forces and information but are unable to see or identify how they themselves are being influenced by the same forces.
For instance, it is easy to see a friend being influenced by a politician or religious leader that you do not support. However, a bias blind spot would make it to where you are less likely or unable to identify similar influences from a politician or religious leader that you support.