When you are talking about a behavior that falls outside of the basic norms of the human experience then often this is called abnormal psychology. This is a broad term that includes a lot of different types of afflictions and behaviors. Each one is going to be observed in a person and to develop a study about it there must be enough of a different c that exists that makes others see a difference. It is important to realize, that many different behaviors can be ruled as abnormal underneath different concepts of behavior. For example, there are different behaviors which are quite normal for someone who is 14 years old but are abnormal for someone at the age of 80 to experience. It means simply that the behavior is outside of the bell curve of observation that is deemed, normal. It is also important to understand that all people have unique personality characteristics which they display. Just because someone is unique there is no reason to label them as abnormal. In fact the people who are not displaying unique thought and behavior should be examined much more thoroughly than those who are expressing original thought and behavior.
Not Good or Bad
Most scientists will distinguish that behaviors which are deemed abnormal or normal should not be equated with the values of good or bad. They would give an example of someone that falls outside of the norm in intelligence or creativity that they would not be looked at as unlucky for having this quality. They would be considered lucky to be smarter although they were falling in the abnormal psych range. However this is just window dressing to the problem of labeling people and putting their behavior in a box that can be observed and evaluated for others to understand.
First there is the behavioral approach to labeling people as abnormal. This comes from being able to observe the behaviors of people which put them outside the norm. A therapist might try to replace or make the behavior something that a person might try to avoid. Secondly there is a medical approach. They look at the biological causes of the abnormal behavior and look for ways to correct it and make people more uniform with society. They can do it through either drugs or surgery. Finally there is the cognitive approach to treatment, where they look at the inner causes of the abnormal behavior and try to correct it by addressing the stimulus that brings on the behavior.
Simply because someone acts a little different or thinks a little differently does not make them a bad person. In fact, the label of abnormal brings with it a stigma that will be hard for the people diagnosed to overcome in any way. Although there are times when a person can be harmful to himself or others, but if there is no imminent harm occurring then it is questionable as to why there should be any treatment at all.