Sigmund Freud believed that the personality develops in infancy as the child is trained to control bodily functions. Freud's model of personality is divided into three parts. The original, unsocialized urges arise out of the id. The norms, values and feelings taught through socialization belong to the superego and the ego is one's conception of oneself in relation to others. Behaviorism takes the opposite view from that of sociobiology.
Behaviorists believe that all behaviors are learned.
Ivan Pavlov demonstrated that conditioned reflexes could be developed by training a dog to salivate at the sound of a bell. John B. Watson showed that emotions such as fear could also be conditioned. Feral children are children who have been raised in isolation. Studies of such children show that the absence of parental love and nurturance damages the individual's ability to become a social being. Studies which compare children reared in orphanages with those reared in traditional families show that the former are more likely to develop emotional problems.