Introduction to Abnormal Behavior
Psychologists agree that mental disorders are serious debilitating illnesses that affect the brain
and one’s ability to function daily. However, defining the term mental illness has its challenges.
The psychology field has multiple definitions of the term mental illness, but psychologists tend to
agree that mental illness affects a person’s thinking (cognition), behavior and emotional state.
According to the Diagnostic Statistical Manual-5 (DSM-5; 2013), mental illness is defined by the
four criteria.

According to Durand and Barlow (2019), psychological disorder is a dysfunction associated with
distress or impairment in functioning that is not atypical or a culturally expected response.
However, defining and differentiating abnormal behavior from that of normal behavior can
present some difficulties. For instance, consider that depending upon a society’s mores and
norms, what is considered normal in one society may not be considered normal in another.
Another example is trying to determine a person’s level of dysfunction; it can include not
functioning normally in one or more areas such as cognition, emotion, and behavior. The
individual who cries a lot or the teenager that binge eats may be showing emotional dysfunction.
The individual must be showing personal distress for the behavior to be considered abnormal as
well; yet, how should a person’s level of distress be identified?
References:
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders
(5th ed.). Arlington, VA: American Psychiatric Publishing.
Durand, M. V., & Barlow, D. H. (2019). Essentials of abnormal psychology. (8th ed.). Mason, OH:
Thomson Wadsworth.
To prepare for this week’s Discussion Board, review the following video in addition to this week’s
assigned Reading: