Stimming is a jargon term for a stereotypy, a repetitive body movement that self-stimulates one or more senses in a regulated manner. It is one of the symptoms listed by the DSM IV for autism, although it is observed in about 10 percent of non-autistic young children. Many autistics have no stims.[1] Common forms of stimming among people with autism include hand flapping, body spinning or rocking, lining up or spinning toys or other objects, echolalia, perseveration, and repeating rote phrases.[1]
There are many theories about the function of stimming, and the reasons for its increased incidence in autistic people. For hyposensitive people, it may provide needed nervous system arousal, releasing beta-endorphins. For hypersensitive people, it may provide a "norming" effect, allowing the person to control a specific part of their sensorium, and is thus a soothing behavior.[2]
From Wikipedia.org