Self deception
The act in which people lie to themselves is called self deception. This odd behaviour can be seen in the large population, where they see the world the way they would like to be rather than the way it is. Small lies or faking are not the part of self deception. In this case, people are well aware about things that are false, but they still speak about that, which are more complicated.
The main problem of people with the self -deception trait is that it is done intentionally. The strong belief of falsehood comes from inside their body, it arises because of emotions, memories, desires, ideologies and elements of subjective culture acquired from socialization. It’s impossible to change the belief of a self-deceptive person about something which is not true. If people have large self deceptions they might be mentally ill.