Now write that down on a piece of paper. Describe what that aspect of their personality is like, and how you react in your thoughts, feelings, and behavior toward that part of their personality. At this point, they are usually a bit puzzled. Now think about your parents. If so, maybe this reaction to the person you described is a kind of transference from your relationship with your parent.
Some students immediately see the connection.
Some will not. To increase the power and complexity of the exercise, I explain that the transference may be more tricky than simply reacting to others the way you reacted to your parent. But a significant number still don't. The person that the student describes in the exercise may indeed be something like the parent.