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 (2013), 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?