Hypotheses are that there is inwardly directed anger, introjection of loss of love object, severe superego demands, excessive personality needs narcissistic, oral and anal, loss of self-esteem and deprivation. in the mother-child relationship during the first year. This was first the belief of Freud, then that of other proponents of psychodynamics. Freud also believed that many cases of depression were actually biological. He said there must be triggers to cause these changes in the brain. One life change he has focused a lot of research on is that depression can be linked to loss or rejection by a parent early in life. Depression is a lot like grief in that it is a reaction to the loss of a relationship or someone important. These findings are better supported than most other research in the field of psychology. But there are still many questions to ask. Finally, I will introduce the behavioral theory of psychology. Behavioral theory of psychology is the branch of psychology that focuses on people's behaviors. This includes their actions, emotions and thoughts. It also focuses on how the environment can shape our behaviors. The main focus is on observation behavior and the conditions through which people will learn certain behaviors. This is done primarily through the processes of classical and operant conditioning