Self-stimulatory behavior, also known as stimming and self-stimulation, is the repetition of physical movements, sounds, or repetitive movement of objects common in individuals with developmental disabilities, but most prevalent in people with autism spectrum disorders. It is considered a way in which autistic people calm and stimulate themselves. Therapists view this behavior as a protective response to being overly sensitive to stimuli, with which the individual blocks less predictable environmental stimuli.Sensory processing disorder is also given as a reason by some therapists for the condition. Another theory is that stimming is a way to relieve anxiety, and other emotions.
Common stimming behaviors (sometimes called stims) include hand flapping, rocking, excessive or hard blinking, pacing, head banging, repeating noises or words, snapping fingers, and spinning objects. Stimming is almost always a symptom of autism, but it is also regarded as part of some non-autistic individuals' behavioral patterns. The biggest difference between autistic and non-autistic stimming is the type of stim and the quantity of stimming.
In the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association, this type of behavior is listed as one of the symptoms of autism or "stereotyped and repetitive motor mannerisms". There are numerous ways to reduce or eliminate stereotypic behaviors. Some of them include providing an individual with alternative forms of stimulation; drugs have been used to reduce stimming (however, it is not clear whether the drugs are actually beneficial or restrict the individual from finding relief).