The assumptions are that there is anger directed towards the inside, introjection of the loss of the love object, serious demands of the Superego, excessive narcissistic, oral and anal needs of the personality, loss of self-esteem and deprivation in the mother-child relationship during the first year. This was initially the belief of Freud and then of other supporters of psychodynamics. Freud also believed that many different cases of depression were actually biological. He said there had to be triggers to make these changes in the brain. One life change that much of the research has focused on is that depression may be linked to the loss or rejection of a parent early in life. Depression is very similar to grief in this sense, it is a reaction to the loss of a relationship or significant other. These findings are better supported than most other research in the field of psychology. But there is still room for many questions. Finally I will present 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 primary focus is observational behavior and the conditions through which people will learn certain behaviors. This occurs primarily through the processes of classical and operant conditioning