Standing apart from psychoanalysis, the field of personality psychology was developed in the 1930's by Harvard theorists Murray and Allport, and worked on further by Cattell, among others.

Allport saw personality less as a reaction to outside events than as a changing, internal process. Personality traits run from being specific to a certain behavior to a general way of being in the world. Three kinds of traits grouped by Allport are:

1. Secondary traits are only present under certain conditions.
2. Central traits are the general traits that are found in different degrees in everyone.
3. Cardinal traits are those that contribute to a dominant feature in someone's personality.

Allport also concluded that you can understand a person's philosophy of life by finding out what his/or her set of values is. Allport, Vernon, and Lindzey created the Study of Values, an assessment tool that measures one's moral/ethical world view according to six attitudinal categories:

1. Theoretical
2. Economic
3. Aesthetic
4. Religious
5. Social
6. Political