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This study was designed to test whether there is a functional relationship between sensory stimulation and stereotyped movements (SM). Four children with autism and intellectual disability (according to DSM-IV criteria) who showed stereotyped movements were studied. The Short Sensory Profile was used to define whether a child perceived stimulation within each sensory modality as aversive, attractive, or neutral. The Stereotyped and Self-Injurious Movements Interview was used to identify each child's repetitive movements. Children were then exposed to sensory stimuli that were neutral, aversive or attractive. Results indicate that children: (a) initiate or increase stereotyped movements immediately following the onset of an aversive stimulus, (b) terminate or decrease stereotyped movements following the onset of an attractive stimulus and (c) initiate or increase stereotyped movements during periods of neutral stimulation. We conclude that stereotyped movements are functionally related to sensory stimulation; individuals who frequently engage in stereotyped movements may do so in order to cope with under-stimulation and aversive over-stimulation.
Stereotyped movements (SM), or stereotypies, are patterned repetitive movements that share at least three characteristics: a high frequency of repetition, an invariant form, and an inappropriate or odd manifestation such that the movement lacks an obvious goal. Typical SM include rhythmic body rocking, head bobbing, arm or hand flapping, eye rolling, finger wiggling, finger waving (in front of the face), and hair twirling (Schopler, 1995).
Stereotyped movements are a feature of normal behaviour, especially during infancy. Among adults, they are especially evident when a person is bored or anxious (de Lissavoy, 1961; Thelen, 1979). More commonly, SM appear in captive animals, in persons who have mental illness or a disability, and in persons given stimulant drugs (Mason, 1991). Most commonly, SM are observed in individuals with autism - whether or not the person is also intellectually disabled (Bartak & Rutter, 1976). Among individuals with autism and profound intellectual disability, elaborate motor routines may be the only way of expressing the restrictive repertoire of activities and interests that contribute to the diagnosis of autism (Schopler & Mesibov, 1995; Gillberg & Coleman, 1992). Among individuals with autism who are less intellectually disabled, repetitive movements may include lining objects, flicking light switches, or showing attachment to and manipulating an object like a string, a rubber tube, or a...