The concept of personality refers to the profile of stable beliefs, moods, and behaviors that differentiate among children (and adults) who live in a particular society. The profiles that differentiate children across cultures of different historical times will not be the same because the most adaptive profiles vary with the values of the society and the historical era. An essay on personality development written 300 years ago by a New England Puritan would have listed piety as a major psychological trait but that would not be regarded as an important personality trait in contemporary America.
Contemporary theorists emphasize personality traits having to do with individualism, internalized conscience, sociability with strangers, the ability to control strong emotion and impulse, and personal achievement.
An important reason for the immaturity of our understanding of personality development is the heavy reliance on questionnaires that are filled out by parents of children or the responses of older children to questionnaires. Because there is less use of behavioral observations of children, our theories of personality development are not strong.
There are five different hypotheses regarding the early origins of personality (see accompanying table). One assumes that the child's inherited biology, usually called a temperamental bias, is an important basis for the child's later personality. Alexander Thomas and Stella Chess suggested there were nine temperamental dimensions along with three synthetic types they called the difficult child, the easy child, and the child who is slow to warm up to unfamiliarity. Longitudinal studies of children suggest that a shy and fearful style of reacting to challenge and novelty predicts, to a modest degree, an adult personality that is passive to challenge and introverted in mood.
A second hypothesis regarding personality development comes from