Abnormal Psychology

Abnormal psychology is the specific field of psychology concerned with the study of abnormal behavior.

Abnormal behavior refers to observable actions considered to be maladaptive or deviant by the social culture in which they occur. Although there is not consensus regarding which specific behaviors should be classified as abnormal, psychologists have defined several consistent criteria for purposes of classification and treatment. First, the behavior occurs infrequently in the dominant culture and therefore deviates from statistical norms. Second, the behavior is apart from the social rules of acceptable behavior. Third, the behavior must be maladaptive: It has adverse effects on the individual or on the individual's social group. Fourth, abnormality may be defined based on a person's internal feelings of distress, unease, depression, or anxiety rather than any specific behavior exhibited.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is a classification system of abnormal behaviors, which is designed to help psychiatrists, psychologists, and other behavioral health professionals to diagnose and treat mental and behavioral health disorders. DSM-5 includes the major, or statistically significant, categories of abnormal behavior. Among these major categories are anxiety disorders, such as obsessive-compulsive disorders and phobias; affective disorders, which are disturbances of mood such as depression; schizophrenia spectrum and other psychotic disorders, which are characterized by major disturbances in personality and distortion of reality; and personality disorders.


Not providing appropriate adjustment to an environment and leading to negative effects on the individual.
An extreme and irrational fear.

Although psychologists use similar criteria to diagnose abnormal behavior, the principles they employ to understand and treat various mental disorders vary widely based on their theoretical framework. For instance, a psychologist with a psychoanalytic approach may explain depression as a reaction to loss, worsened by anger turned inward. A behavioral psychologist may posit that the depressed person suffers from a lack of positive reinforcement: Experiences outside the self, in the world, have caused his disease. A cognitive theorist would focus on changing negative thought patterns and attitudes of a depressed person because these patterns can contribute to psychological illness. Finally, a psychologist with a strongly biological perspective would suspect a chemical imbalance in the nervous system of the depressed person is causing the disorder. Research has shown that a number of these factors may come into play in the life of an individual experiencing a mental disorder characterized by abnormal behavior. Much mental illness is thought of as multifactorial.

See also Antisocial behavior ; Assessment, psychological ; Behavior therapy ; Clinical psychology ; Psychosis ; Psychotherapy .



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Beidel, Deborah C., Cynthia M. Bulik, and M. A. Stanley. Abnormal Psychology. Upper Saddle River, NJ: Prentice Hall, 2010.

Meyer, Robert G., and Christopher M. Weaver. Case Studies in Abnormal Behavior. Boston: Pearson, 2013.

Smoller, Jordan W. The Other Side of Normal: How Biology Is Providing the Clues to Unlock the Secrets of Normal and Abnormal Behavior. 2013.

Weis, Robert. Introduction to Abnormal Child and Adolescent Psychology. 2013.


McLeod, Saul. “Abnormal Psychology.” http://www.simplypsychology.org/abnormal-psychology.html (accessed July 17, 2015).


Anxiety and Depression Association of America, 8701 Georgia Ave., Ste. 412, Silver Spring, MD, 20910, (240) 485-1001, http://www.adaa.org .