Projection is a psychological mechinism where people project their own traits onto others.

When projecting you tend to see your own negative traits in the people you interact with. It's a common human behavior.

And it has a lot of implication for poker.

People who bluff too much tend to also call too much. They do it because they project. They know they bluff too much and the fear that other's do also. It's an important human trait to keep in mind when you're thinking about a thin value bet. If they tend to bluff to much, make that thin value bet every time.