An adaptation of Gardner's ideas of interpersonal and intrapersonal intelligence, EQ was brought forth by Daniel Goleman as an alternative to traditional IQ for indicating which people tend to be more successful in life.

Prior to Erik Erikson, most theorists held that development ended in adolescence or early adulthood, after that, they argued, personality was essentially stable. Erikson argued that adults of all ages continued to face new challenges that shape their personalities as they age. Erikson's conception of development across the lifespan is unique and has continued to influence modern personality theorists and humanistic psychotherapists long after his death. 

The idiographic view supports that people are highly unique in their personalities and psychological structure to the point where they can't be compared to other people. Those who conduct research in support of this view often use case studies as opposed to general surveys.

Evolutionary psychology describes the idea that human behavior has evolved over time and has been passed down from generation to generation. In evolutionary psychology, humans’ behavioral tendencies were passed down from our ancestors.

Countertransference describes when an analyst becomes emotionally attached or involved with a patient as if they are an important person in their life. The opposite of this phenomenon, when a patient becomes attached to an analyst, is called transference.

Freud outlined three basic kinds of anxiety (anxiety, for Freud, being the feelings associated with an imminent danger). Realistic anxiety is fear of being in genuine danger. It occurs when there is an actual threat to the person. Moral anxiety is the fear of one's internal values being challenged or compromised. Neurotic anxiety is the fear of the id overpowering the ego. 

According to Freud, repression was the mind’s first defense against harmful memories or psychological issues. Freud defined repression as the ego blocking an inappropriate wish or desire from being known or recognized consciously.

Projection is giving an unconscious desire or inappropriate behavior to someone else. In this example, Tommy is a liar, and recognizes that about himself in other people, instead of realizing that he is the one with a lying problem. Think of a movie projection, which puts forth an image onto a blanks screen.

Reaction formation is described as expressing an impulse by doing the opposite. Projection describes the process of denying a negative aspect of one's own personality by projecting it onto someone else ("I'm not irritable, you are."). Identification describes the process of takes in and models one's own behavior on another's. Repression refers to the process of forgetting, or pushing away, traumatic childhood experiences.

Regression is described as reverting back to an earlier behavior used to express an impulse. Common behaviors of regression are childhood behaviors like bed wetting or thumb sucking.