Abnormal behavior is defined as behavior that is considered to be maladaptive or deviant by the social culture in which it occurs. Though disagreement exists regarding which particular behaviors can be classified as abnormal, psychologists have defined several criteria for purposes of classification. One is that the behavior occurs infrequently and thus deviates from statistical norms. Another is that the behavior deviates from social norms of acceptable behavior. A third is that the behavior is maladaptive, that it has adverse affects on the individual or on the individual’s social group. Lastly, abnormality may be defined based on the subjective feelings of misery, depression, or anxiety of an individual rather than any behavior he exhibits. (The Diagnostic and Statistical Manual of Mental Disorders, 4th edition, DSM-IV,), is a classification system of abnormal behaviors which aids psychologists and other mental health professionals in diagnosing and treating mental disorders. DSM-IV includes the major categories of abnormal behavior which are anxiety disorders, such as obsessive-compulsive disorders and phobias; affective disorders, which are disturbances of mood such as depression; schizophrenic disorders, which are characterized by major disturbances in personality and distortion of reality; and various personality disorders. While psychologists use similar criteria to diagnose abnormal behavior, their perspectives in understanding and treating related disorders vary greatly. For instance, a psychologist with a psychoanalytic approach would explain depression as a reaction to loss, worsened by anger turned inward. A behavioral psychologist would assume a lack of positive reinforcement to be a significant cause in the disease. A cognitive theorist would focus on the negative thought patterns and attitudes of an individual in contributing to his depression. And a psychologist with a biological perspective would consider a chemical imbalance in the nerv>