Two important stage theorists of psychological development are Sigmund Freud and Erik Erikson. Each period has a sexual focus that is gratified, frustrated or overindulged, leaving a lasting imprint on personality. . As he attempts to gain more control he derives pleasure from exploring the environment, testing the strength of his will power over parents and authority figures. A crucial event to Freud was toilet training that represents society's systematic efforts to control the child's biological urges. They openly explore and play with their bodies and enjoying being naked.
Children also become interested in the parent of the opposite sex.
If the girl's attempts to attract his attention are successful and her father responds fully and positively, she gains sex-role assuredness and a positive relationship with men. As the fulfiller of all the boy's needs for security, love and comfort, the boy is strongly attached to the loving mother and threatened by the father, the obvious competitor for mom's affections. Boys may develop a castration complex towards the father who might punish desires for his mother. With the advent of puberty sexual urges reappear and the sexual energy is normally channeled toward peers of the opposite sex. Each stage of psychosocial development with the crisis and favorable social condition and outcome and possible negative conditions and outcome is reviewed below.