Perception [lesson 2] is the process of receiving information through our senses. We then make an interpretation and, often, that interpretation becomes a self-fulfilling prophecy. "self-fulfilling prophecy" [ lesson 15] because it is based upon a habit of creating a certain picture in your mind. Projection is not all bad, as it assists us in experiencing our way of reality. However, certain types of projections, can be harmful, such as imputing a person's motives.
Situational attribution [lesson 4] is the process of projection whereby we attribute to situations reasons for motives. Dispositional attribution is projection whereby we attribute to others character as reasons for their motives. Distrust is often an example how projections can hinder, or destroy, a relationship. Self-disclosure is a process of giving feedback to others on how you are reacting to a situation which may increases your awareness of projection.
Leon Festinger's "Law of cognitive dissonance" provides an explanation for the precursor of projection. When a motivational state exists which puts our beliefs, feelings, etc. in contradiction with our cognition, i.e., our conscious thoughts, we attempt, to justify, or explain them, in order to get them to appear consistent. 
Pay attention to your feelings, and your behavior. What happens? What is really behind the mask of "saying no"? What have you learned about yourself regarding your projections? You may be sure you are projecting anytime you use the following words:, "all", "never", and "always". What are your underlying beliefs, or pictures of the mind, that necessitates your use of these words?. When you find that you have the same patterns happening over and over in relationships, you can be certain that you are involved in projection.
1. George Weinberg ,Dianne
Rowe, The Projection Principle, New York, St .Martin Press,1988,