1. Personality Theorists - Psychoanalytical and Humanistic

Maslow - Hierarchy of needs

Maslow's theory of the hierarchy of needs

The most basic of needs, those that keep us alive are at the bottom.  If these needs are not met, people can not progress up the pyramid to achieve their fullest potential. 

Maslow suggested that if you do not get some of these needs met, or there is a problem at one of the levels, you may become fixated at that stage and may not be able to move on in your personality development.   For example, if you are in a war as a child and are deprived of your basic needs, you may become obsessed with collecting or stocking the pantry.  A divorce in your family, may cause you to be insecure in your marriage as an adult.