havioral models of psychological disorders emerged during the late 1800’s and early 1900’s.
             The biological model of psychological disorders states that abnormal behavior is caused by the malfunctioning of the nervous system or the endocrine glands, or in other words physiological, and is most times attributable to heredity factors.
             Freud developed the psychoanalytic model of psychological disorders. It states that behavior disorders are symbolic expressions of unconscious internal conflicts that can be traced to the early years of life. This model implies that people should be conscious of the fact that the sources of their problems lie in their childhood and infancy before they can resolve their problems effectively. For example, a woman who has problems relating to men may be unconsciously expressing strong feelings of insecurity and loneliness that was manifested as a result of not having her father around when she was a child.
             The cognitive-behavioral model of psychological disorders grew through research on learning and cognition during the 20th century. It implies that abnormal behavior is much like all behaviors, a result of learning. In a sense it says that negative behavior and thinking (i.e. anger, anxiety, dejection, hatred, sexual deviations, and similar behaviors) are learned and therefore can be unlearned.
             The diathesis-stress model of psychological disorders suggests that some people are biologically prone to developing a particular disorder under stress whereas others are not. For example, someone biologically predisposed to alcoholism, depression, phobias, schizophrenia, or similar disorders who will tend to exhibit the disorder when particularly affected by stress.
             The systems theory says that emotional problems are "lifestyle diseases" like high blood pressure and many other physical illnesses that are caused by a combination of biological risks, psychological stresses, and societal pressure...