Abnormal behavior is considered to be a psychological disorder. In behaving abnormally, the reactions of others can range from mild displeasure to profound distress and suffering. For the individual who exhibits the abnormal behavior, the results can range from suffering the disapproval of others, to an inability to survive because of a lack of ability to comprehend reality or to behave within the cultural and accepted norms.
Many people suffer from some psychological disorder or disorders. The effect of the disorders causes an impairment that prevents them from living whole lives that are taken for granted by those who can go to work, enjoy relationships with family and friends, and manage internal and external challenges.
A good definition of abnormal behavior is "It is a psychological dysfunction within an individual associated with distress or impairment in functioning and a response that is not typically or culturally expected." (1) There are three elements based on this definition: psychological dysfunction; distress or impairment in functioning; and atypical or unexpected response.
But defining "abnormal" is not as easy as the clean definition would imply. If we could transport a hundred "normal" people from 200 years ago, into an urban setting today, most of them would be locked up or shot within a few hours or days. If a hundred of us "normal" people were suddenly transported to 200 years ago, the same would probably happen to us. In other words, what is considered "normal" in one era becomes abnormal, and even criminally abnormal in another era, indicating that society dictates what is "normal" and "abnormal" psychology.
There are constants, however, and they are ability to thrive and to care for onself; ability to comply with the law; ability to perceive reality and to react appropriately to people and events; and ability to not harm the self or others. The constant challenges to those abilities can come from the early childhood development of maladaptive thought processes and behaviors, or from physiological flaws and faults that a person is born with, or from brain damage/modification that comes from injury, illness or substance abuse.
"Psychological dysfunction refers to a breakdown in cognitive, behavioral, or emotional functioning." (2)
One criteria that may or may not be present, is distress. All humans suffer from distress at one time or another and normal individuals manage to resolve their distress in healthy or normal ways through their healthy faculties. Many profoundly psychologically dysfunctional people suffer no distress at all from their distress and even prefer their condition, as with manic sufferers who persistently resist treatment because they "...enjoy the manic state". (3)
Impairment is another criteria which may or may not be present. Being a procrastinator or engaging in the odd eating binge enough times to be overweight are not signs of psychological dysfunction. Extremes of normal human frailties, flaws and faults, however, can be severe enough to impair a person's ability to function. Fear that is profound enough to prevent a person from ever leaving their home is an example of impairment, as opposed to a simple phobia about going out when there is a storm.
The criteria of atypical or unexpected response ranges from the individual who has a few crazy ideas and behaviors to the individual who cannot control their behavior so that it falls within the norms of society and the law. The concept of "dysfunctional harm" comes into play. The DSM-IV-TR has a definition of abnormal that should apply, regardless of culture or location in time or place:
"...behavioral, emotional or cognitive dysfunctions that are unexpected in their cultural context and associated with personal distress or substantial impairment in functioning." (4)
The DSM V is in the working stages and it is expected that more work on the definition of "abnormal" will result in more useful understandings. Two areas that are included in the Websters definition of "abnormal psychology" are the areas of examining dream states and hypnosis.
1, 2, 3, 4
V. Mark Durand and David Barlow, "The Essentials of Abnormal Psychology", 2006, Thompson Wadsworth