Written by Stephen M. Edelson, Ph.D.
Stereotypy or self-stimulatory behavior refers to repetitive body movements or repetitive movement of objects. This behavior is common in many individuals with developmental disabilities; however, it appears to be more common in autism. In fact, if a person with another developmental disability exhibits a form of self-stimulatory behavior, often the person is also labelled as having autistic characteristics. Stereotypy can involve any one or all senses. We have listed the five major senses and some examples of stereotypy.
Stereotypic Behaviors Related to Senses
- Visual staring at lights, repetitive blinking, moving fingers in front of the eyes, hand-flapping
- Auditory tapping ears, snapping fingers, making vocal sounds
- Tactile rubbing the skin with one's hands or with another object, scratching
- Vestibular rocking front to back, rocking side-to-side
- Taste placing body parts or objects in one's mouth, licking objects
- Smell smelling objects, sniffing people
Researchers have suggested various reasons for why a person may engage in stereotypic behaviors. One set of theories suggests that these behaviors provide the person with sensory stimulation (i.e., the person's sense is hyposensitive). Due to some dysfunctional system in the brain or periphery, the body craves stimulation; and thus, the person engages in these behaviors to excite or arouse the nervous system. One specific theory states that these behaviors release beta-endorphins in the body (endogeneous opiate-like substances) and provides the person with some form of internal pleasure.
Another set of theories states that these behaviors are exhibited to calm a person (i.e., the person's sense is hypersensitive). That is, the environment is too stimulating and the person is in a state of sensory-overload. As a result, the individual engages in these behaviors to block-out the over-stimulating environment; and his/her attention becomes focused inwardly.
Researchers have also shown that stereotypic behaviors interfere with attention and learning. Interestingly, these behaviors are often effective positive reinforcers if a person is allowed to engage in these behaviors after completing a task.
There are numerous ways to reduce or eliminate stereotypic behaviors, such as exercise as well as providing an individual with alternative, more socially-appropriate, forms of stimulation (e.g., chewing on a rubber tube rather than biting one's arm). Drugs are also used to reduce these behaviors; however, it is not clear whether the drugs actually reduce the behaviors directly (e.g., providing internal arousal) or indirectly (e.g., slowing down one's overall motor movement).