There are three main psychological theories (or "perspectives") regarding our personalities. I shall list them in turn and give a brief description.

The Trait Perspective

Traits, for the purposes of this theory, are defined as stable, enduring characteristics that contribute to personality. These are used to characterise people into different personality types.

Five distinct traits can be identified which define a personality:

• Emotional stability
• Extraversion / introversion
• Openness to experiences
• Agreeableness
• Conscientiousness

Personality typing is often self assessed using written personality tests.

The Humanistic Perspective

This theory is based on the idea that people are generally good and strive to better themselves.

There were two main practitioners of this theory, who stated the following:

• Abraham Maslow: Self-actualisation is the goal
• Carl Rogers: Our self-concept affects how we feel about the world.

The Social-Cognitive Perspective

This suggests that our personality is shaped by our interactions with the environment:

• Observing others
• Modelling their behaviour

How we think about our life affects our behaviour. (This is similar to the Humanistic Perspective.) There are two main beliefs we can have about our lives:

• Internal locus of control: you control your own destiny
• External locus of control: fate controls your destiny

Reference: Exploring Psychology (5th Edition) by David G. Meyers

For mostly historical reasons, we should include the Psychodynamic perspective. In this model, personality comes from the interaction of three basic psychic structures, the id, ego, and superego. Freud's theory came at a time when it was fashionable to apply the concepts of thermodynamics to pretty much everything. The id, ego, and superego have to share a finite amount of psychic "energy", and growth and development is a matter of approaching some kind of thermal equilibrium. The whole idea seems pretty hokey nowadays, but I'm sure it seemed like a good idea at the time.