abnormality

Feature or occurrence that is not normal; an aberration or irregularity; also the state of being abnormal. The term is widely used in a medical context. In psychology, because of disagreement about defining ‘normalness’, other terms are now preferred, such as ‘deviant’ or ‘maladjusted’. In statistics, abnormality denotes variance from the norm.

Abnormal psychology concerns itself with unusual or deviant behaviour, with mental disorders, and with unusual experiences reported by normal individuals. Several approaches are employed – biological, physiological, behavioural, psychodynamic, and sociological – and the subject area overlaps with that of psychiatry, clinical psychology, and parapsychology. Many of the phenomena are relevant to general psychology and are studied under its various headings.