Many individuals on the autism spectrum exhibit some form of repetitive motor behavior.1 Just as they may speak a word or phrase over and over again (echolalia), or even just utter the same sound repeatedly, they may flap their hands, flick their fingers, bang their heads, grind their teeth, or endlessly perform other seemingly random physical acts. The psychiatric term for this is stereotypy, but these actions are more often referred to as "repetitive behaviors" or "stimming" - which is short for self-stimulation.

Although these types of behaviors do occur in very young "typical" children, as well as in those with other developmental or psychiatric disorders, it has been shown that they occur more often and more intensely in autism.2 These repetitive behaviors appear to be tied to developmental level and IQ in individuals with ASDs. Those who are younger and/or lower functioning display a lot more of the physical stimming behaviors (like hand flapping).3,4 Those who are higher functioning may also perform these behaviors, especially when very young, but tend to demonstrate more complex behaviors,5 compulsions, or intense areas of interest as they get older.6 (See Restricted Interests.)

Stimming behaviors can be very unnerving for families of those with an ASD. Imagine a child who walks around the backyard in a circle, uttering a strange cry over and over, smacking his palm against the back of his other hand.for hours. How much of this should they permit? Is the behavior actually helping the child somehow, or is it random and purely dysfunctional?

The experts are not in agreement. Some have proposed that these behaviors help people with ASDs block out overwhelming sensory input. Others have suggested that they are used to get attention or to escape unpleasant tasks. Still others have described them as a sort of retreat to familiar ground; individuals with ASDs will engage in them when faced with unfamiliar situations that defy their coping skills.7 Considering the wide variety of behaviors, there is probably more than one valid explanation.

When a "stimming" behavior crosses the line into self-injury, parents and other supporters of those with ASDs become most desperate to interfere. Self-injurious behaviors occur most commonly among the lowest-functioning individuals, and include hand biting, head banging, or scratching so intense that they cause physical damage.8 This is thought to be entirely different from the kind of self-inflicted injury that might be carried out by a socially, intellectually normal person with some other kind of psychiatric issue, such as borderline personality disorder.9 It's believed that, for those with ASDs, self-injurious behaviors may often serve a social-communication function - a way to get a message across when language is either not present or not sufficient to do so.10 There is also evidence that neurochemical abnormalities are associated with such behaviors, and that chronic health issues - like ear infections and gastrointestinal problems -- can make a tendency to self-injure much worse.11

Whatever the case, witnessing a child injure him- or herself is terribly upsetting, and parents or caregivers are driven to try all possible solutions, from medications to attempts at behavior modification, to decrease or eliminate it.

1. American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., rev.). Washington DC: Author.
2. Bodfish, J. W., Symons, F. J., Parker, D. E., & Lewis, M. H. (2000). Varieties of repetitive behavior in autism: Comparisons to mental retardation. Journal of Autism and Developmental Disorders, 30(3), 237-243(7). Abstract
3. Campbell, M., Locascio, J.J., Choroco, M.C., Spencer, E.K., Malone, R.P., Kafantaris, V., & Overall, J.E. (1990). Stereotypies and tardive dyskinesia: Abnormal movements in autistic children. Psychopharmacology Bulletin, 26(2), 260-6. Abstract
4. Cuccaro. M.L., Shao, Y., Grubber, J., Slifer, M., Wolpert, C.M., Donnelly, S.L., Abramson, R.K., Ravan, S.A., Wright, H.H., DeLong, G.R., & Pericak-Vance, M.A. (2003). Factor analysis of restricted and repetitive behaviors in autism using the ADIR. Child Psychiatry and Human Development, 34(1), 3-17. Abstract
5. Militerni, R., Bravaccio, C., Falco, C., Fico, C., & Palermo, M.T. (2002). Repetitive behaviors in autistic disorder. European Child & Adolescent Psychiatry, 11, 210-218. Abstract
6. South, M., Ozonoff, S., & McMahon, W.M. (2005). Repetitive behavior profiles in asperger syndrome and high functioning autism. Journal of Autism and Development Disorders, 35(2), 145-158. Abstract
7. Turner, M. (1999). Annotation: Repetitive behavior in autism: A review of psychological research. Journal of Child Psychology and Psychiatry, 40(6), 839-849.
8. Matson, J.L., & Nebel-Schwalm, M. (2006). Assessing challenging behaviors in children with autism spectrum disorders: A review. Research in Developmental Disabilities, in press - available on-line 9/14/06. Abstract
9. Schroeder, S.R., Oster-Granite, M.L., Berkson, G., Bodfish, J.W., Breese, G.R., Cataldo, M.F., Cook, E.H., Crnic, L.S., DeLeon, I., Fisher, W., Harris, J.C., Horner, R.H., Iwata, B., Jinnah, H.A., King, B.H., Lauder, J.M., Lewis, M.H., Newell, K., Nyhan, W.L., Rojahn, J., Sackett, G.P., Sandman, C., Symons, F., Tessel, R.E., Thompson, T., & Wong, D.F. (2001). Self-injurious behavior: Gene-brain-behavior relationships. Mental Retardation and Developmental Disabilities Research Reviews, 7, 3-12. Abstract
10. McClintock, K., Hall, S., & Oliver, C. (2003). Risk markers associated with challenging behaviours in people with intellectual disabilities: A meta-analytic study. Journal of Intellectual Disability Research, 47(6), 405-416. Abstract
11. Schroeder, S.R., Oster-Granite, M.L., Berkson, G., Bodfish, J.W., Breese, G.R., Cataldo, M.F., Cook, E.H., Crnic, L.S., DeLeon, I., Fisher, W., Harris, J.C., Horner, R.H., Iwata, B., Jinnah, H.A., King, B.H., Lauder, J.M., Lewis, M.H., Newell, K., Nyhan, W.L., Rojahn, J., Sackett, G.P., Sandman, C., Symons, F., Tessel, R.E., Thompson, T., & Wong, D.F. (2001). Self-injurious behavior: Gene-brain-behavior relationships. Mental Retardation and Developmental Disabilities Research Reviews, 7, 3-12. Abstract