Repetitive stereotyped behaviors have been problematic to define due to the variation in the topography of type of movements. Repetitive stereotyped behaviors have been associated with tremor (more or less regular, rhythmic contracting of muscles and their antagonists.) There are various types of tremors: a) tics (sudden, brief, recurrent, inappropriate, and other irresistible movements, simple or complex, without purpose or aim), b) tardive dyskinesia (involuntary movements of the lips, jaws, and tongue), perseveration (repetition of recent movements, action, or speech in spite of the individual’s effort to produce a new movement), c) stereotypy (an action or group of actions or words monotonously repeated or a posture maintained abnormally long), d) mannerism (a normal goal-directed behavior which is performed in a peculiar stylized and idiosyncratic manner) and e) obsessional phenomena (repetitive, purposeless voluntary phenomena which the subject feels compelled to carry out, but does so under the influence of his or her own will) (Frith and Done, 1997). Baker (1992) divided repetitive stereotyped behaviors in two categories: 1) As consequence of a restricted environment and 2) repetitive stereotyped behaviors triggered by the central nervous system. According to Garner (2005) and Turner (1997), repetitive stereotyped behaviors can be defined as behaviors that are inappropriate, repetitive and unvarying in either goal or motor pattern. Repetitive stereotyped behaviors may be subdivided into two basic categories based on the unvarying manner in which the behaviors are repeated: (1) Stereotypies involve the unvarying inappropriate repetition of a particular set of movements and/or body postures that lack any goal or function. (2) Impulsive/compulsive behaviors involve the repetition of an inappropriate goal with variable flexible goal-directed behavior (Garner 2005). Cuccaro and colleagues (2004, 2007) identified two factors in the repetitive stereotyped behaviors: Factor 1) Repetitive sensory motor actions and Factor 2) Resistance to change. Esbensen and colleagues (2008) found that repetitive behaviors are a heterogeneous group of behaviors, with the subtypes of repetitive stereotyped behaviors having their own individual patterns across the lifespan. Stereotyped patterns of behavior include not only excessive atypical movement but also the loss of typical movement (e.g., catatonia) in this broader definition (Stoppelbein, et al. 2005; Heffernan, et al., 2003).
Motor stereotyped behaviors are apparently purposeless ranging from simple movements, such as flapping arms or hands, flipping fingers in front of eyes, making repetitive sounds such as "eeeee" or "dika dika dika", jumping up and down , clenching muscles or turning in circles, clapping and finger tapping, to more complex whole-body movements. Self-injurious behaviors (
According to Turner (1997, 1999) restricted stereotyped behaviors in autism can be divided into “lower-level” behaviors characterized by repetitive movement, and “higher-level'” behaviors characterized by preoccupations, insistence on sameness, and restricted patterns of interest. According to Turner (1997, 1999, Moy, et al., 2008) “higher-level” repetitive stereotypical behaviors (RSB) are more specific to autism than “lower-level”. Abramson and colleagues (2005) found that repetitive stereotyped behaviors in autism may be on a spectrum with obsessive-compulsive traits, which may allow genetic researchers to identify different phenotypes groups in the autism spectrum disorder.
Although self-injurious behavior is not specific for autism spectrum disorder, it constitutes one of the most challenge forms of “lower-level” repetitive stereotyped behaviors.
There are several hypotheses about self-injurious behaviors as a repetitive stereotyped behavior. One leading theory explains repetitive stereotyped behaviors as an attempt to adjust arousal levels to maintain homeostasis by producing needed sensory stimulation or avoiding over-stimulating situations (Frith and Done, 1997). Applied behavior analysis (