Disorders of Habit

Abstract

Stereotyped rhythmic movements usually involve one or more segments of the body and take such forms as head banging, rocking, and flapping of the hands. Epidemiologic studies have shown that a considerable percentage of normal children under 2 years of age engage in such behavior for short periods of time and that the incidence is higher among boys than among girls (DeLissovoy, 1961). More recent studies have shown that both head banging and rocking are more prevalent among boys than girls (male/female ratio of 3:1). In a population of normal children, both types of behavior appear spontaneously before 12 months of age and peak a few months later. A decline sets in after 18 months, and only in about 3% does the behavior persist into the second year of life (Werry et al., 1983). However, in abnormal populations, such as retardates or psychotics, the stereotyped movements persist beyond the age of 2, take exaggerated forms, and may constitute a significant part of the child’s activities. Furthermore, while in young normal children such behavior is limited to situations in which the infant is fatigued, understimulated, or left alone in the crib, in deviant groups the behavior for the most part appears regardless of the nature of environmental stimuli and seems to be the preferred activity for the patient.