The first modern personality trait theorist was Gordon Allport. In the 1930’s, Allport and his students searched through dictionaries to find words that described personality. They started with 17,953 adjectives but settled on 4504 of them.
Allport suggested that most of these traits were “common traits” (traits we all hold in common). Some might have a lot of a common trait but others might have only a smidge. But Allport also proposed that people can have individual traits unique to them.
His morphogenic approach combined individual uniqueness (idiographic traits) and group comparison traits (nomothetic traits). You can compare yourself to others on “agreeable,” “friendly,” and “caring.” Plus you can have your own special nobody-in-the-world-is-like-me traits. Allport bridged the “lots of traits” and the “only a few traits” debate by combining them.
Allport proposed there is a core to personality: a proprium. This central core is our sens of self. It is the “me” we know and feel ourselves to be. This proprium develops in stages. First, we begin early infancy with no sense of self. Second, we become able to tell the difference between our body and external things. This occurs in the second half of the first year.
The third stage of proprium development occurs in year 3. This is when we develop self-identify. We begin to take pride in our accomplishments. Of course, some negativism develops too. Allport’s use of the word “negativity” was sometimes reported as “reverse psychology,” and may have been the origins of that phrase.
The fourth stages of proprium development is the extension of self. In years 4-6, you develop an egocentric self. From your point of view, others are there for you. Santa, God, parents; everyone exists for your benefit. In this stage, self is extended to possessions; everything is “mine.” Self-image also emerges during this period. You begin to have hopes, aspirations, and expectations of others.
The fifth stage is the rational coper. During the period from 6 to 12, you learn to cope rationally. Like Freud’s ego and Piaget’s formal operations, you learn to think things through in your head.
The sixth and last stage is proprium striving. As a teen, you learn how to be an adult and yet remain yourself. You might rebel with the hope that your parents will stop you from doing stupid things. You want to be an adult and develop long-range plans. But you don’t want to leave your “self” behind or take total responsibility for your life.
For more on the subject, check out this video on Modern Trait Theories.