Stimming

Stimming has been interpreted as a protective response to sensory overload, in which people calm themselves by blocking less predictable environmental stimuli, to which they have a heightened sensory processing sensitivity. Stimming can be a way to relieve anxiety and other negative or heightened emotions.

Although some forms of stimming behaviors have typically been shown to be healthy and beneficial—as they help regulate intense sensory experiences, relieve intense emotions such as anxiety, may facilitate understanding and social interactions with other autistic people, may promote pleasant emotions, and facilitate sense of security— stimming is often socially stigmatized. Those who are neurodivergent often feel that they should hide or decrease their repetitive behaviors, by a social process called masking, because they appear to be socially unacceptable and often elicit negative reactions from those who do not understand their cause. While reducing disruptive or inherently harmful repetitive behaviors can be beneficial, there are also potential risks to mental health and well-being in suppressing and masking some autistic stimming behaviors that are not harmful or are adaptive.

Stimming behaviors can consist of tactile, visual, auditory, vocal, proprioceptive (which pertains to limb sensing), olfactory, and vestibular stimming (which pertains to balance). Stimming behaviours include hand flapping, clapping, rocking, blinking, pacing, head banging, repeating noises or words, snapping fingers, toe walking, and spinning objects. In some cases, stimming can be dangerous and physically harmful to the person doing it; for example, individuals may risk injuring themselves by forcefully banging their body parts against walls. Another problem is that repetitive behaviors can disrupt learning and social communication for some autistic individuals in some situations.

Autism

Stimming behavior is almost always present in autistic people, but does not, on its own, necessarily indicate the diagnosis. 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, stimming behavior is described as "stereotyped or repetitive motor movements" and listed as one of the five key diagnostic criteria of autism spectrum disorder.

Different perspectives suggest that stimming involves both sensory and motor functions. Underdevelopment of these sensorimotor functions can result in stimming behaviors produced by the person as a controllable response. One study which interviewed thirty-two autistic adults found that unpredictable and overwhelming environments caused stimming.

Stimming can sometimes be self-injurious, such as when it involves head-banging, hand biting, excessive self-rubbing, and scratching the skin.

As it serves the purpose of self-regulation and is mostly done subconsciously, stimming is difficult to suppress. Managing the sensory and emotional environment while increasing the amount of daily exercise can increase comfort levels for the person, which may reduce the amount of the need for stimming. Consciously or subconsciously suppressing stimming with the aim to present as neurotypical is one type of autistic masking. It typically requires an exceptional effort and can negatively impact mental health and well-being.