Stereotypic Behavior in Persons with Mental Retardation (1994)
©1994, 2013 by Dallas Denny
Source: Denny, Dallas. (1994). Stereotypic behavior in persons with mental retardation. Paper for Dr. Paul Alberto, EXC 725, Georgia State University.
Stereotypic Behavior in Persons with Mental Retardation
By Dallas Denny
For Dr. Paul Alberto
EXC 725
Georgia State University
Spring, 1994
Abstract
Abstract
All vertebrates exhibit rhythmic, repetitive behaviors which occur throughout ontogeny. Most of these behaviors are functional, and some are quite necessary for the continuation of life. When rhythmic behaviors occur without a known functional purpose, they are called stereotypic behavior, or stereotypies. Zoo animals and factory farm animals in small enclosures which restrict freedom of movement and social opportunities frequently engage in stereotypies. Infants with mental retardation have long been known to show a delay in the onset of rhythmic motor patterns. In children and adults with mental retardation, and particularly in those who are severely or profoundly impaired, stereotyped behaviors are very common. Special educators do not typically get to watch the origin of these behaviors, as have some researchers; rather, they are often confronted with well-developed behaviors which appear to be nonfunctional and can occur with such great frequency as to make training difficult. Comparisons of normal and abnormal rhythmic behaviors in normally developing and developmentally delayed humans and comparisons of rhythmic behaviors in human and non-human animals can be of great utility in unraveling the mystery of abnormal stereotypic behaviors. It seems likely that similar factors may be responsible for stereotypies across species.
All vertebrates exhibit rhythmic, repetitive behaviors which occur throughout ontogeny. Most of these behaviors are functional, and some are quite necessary for the continuation of life (Thelen, 1979). Locomotion, breathing, and eye-blinking, for example, are rhythmic behaviors.
When rhythmic behaviors occur without a known functional purpose, they are called stereotypic behavior, or stereotypies. Zoo animals and factory farm animals in small enclosures which restrict freedom of movement and social opportunities frequently engage in stereotypies. Rushen (1984), for example, found tethered sows exhibited a variety of stereotypies. Some of the behaviors were observed to vary systematically, being most frequent before and directly after mealtimes. Other behaviors did not vary with the feeding schedule. The behaviors which were associated with mealtimes were to some extent topographically similar to the natural food-seeking behavior of the species (e.g., rooting). Rushen postulated that the concrete floor and the confining conditions of the small enclosure affected the topography of the behavior.
The stereotypies Rushen observed are not common in free-ranging sows. One might hypothesize the cause of such behaviors might be either sensory or social deprivation. Harlow’s classic (1958, 1962) studies with socially deprived monkeys provides strong evidence for the social deprivation hypothesis—especially since monkeys which were raised with cloth-covered “mothers” showed lower rates of stereotypies than monkeys raised with “mothers” which consisted of wire frames (Harlow, 1958). Monkeys deprived of contact with conspecifics engaged in high rates of body rocking, non-nutritive sucking, and other stereotyped behaviors. However, animals raised in small cages with conspecifics also engage in stereotypies (Singer, 1975); most likely, a combination of factors produces this type of behavior.
Stereotypic behavior in humans was studied by Berkson and his associates in the 1960s (Berkson, et al., 1962, 1965), who focused on persons with mental retardation in institutions. The early studies of Berkson et al. and others were largely descriptive, but unfortunately, the behaviors themselves were not rigorously described. Berkson has kept his interest in stereotypic behavior for more than twenty years (Berkson, et al., 1985, Schwartz, 1985), but the lack of rigor in his early studies has had unfortunate consequences for the study of stereotypies in persons with mental retardation.
Esther Thelen’s (1979, 1981) work with stereotypic behavior in normally developing infants was much more rigorous, for she took an ethological approach. She identified rhythmic behaviors by observation, and then painstakingly described and measured them. Thelen found a variety of rhythmic behavior in the infants she observed, including body rocking, swaying, hand waving, twirling, “pill-rolling,” mouthing, and shaking of objects. These behaviors are probably best not called stereotypies, as they are almost certainly functional in that they help the infant explore his or her own body and its relationship to the world, but they were certainly rhythmic. Thelen’s painstaking ethogram describes precisely which sections of the body are moved, and the temporal sequence of movements. Her work is in contrast to that of other workers, who sometimes describe behavior with some detail, but never in a way which precisely defines it. An example is Stevens’ (1971) description of body rocking:
… rocking behavior (is) thus defined: (a) All subjects must manifest a high probability of persistent back and forth torso rocking while seated either in a chair or on the floor. (b) The body rocking must be clearly defined as a stereotyped behavior, i.e., occurring at regular, persistent rates, varying in form only slightly, and continuing regardless of the environmental stimuli. (p. 77)
Thelen (1979, 1981) would have described the motor groups used, the frequently and amplitude of rocks, and the timing of rocks, with mean and standard deviation.
Infants with mental retardation have long been known to show a delay in the onset of rhythmic motor patterns (Kravitz & Boem, 1971). For the past seven or eight years, Berkson and his colleagues have been looking at the origin and topography of rhythmic movements in children with mental retardation and comparing them to normally developing children. Berkson’s work will doubtless provide hypotheses about the functionality of rhythmic behavior in both groups.
In children and adults with mental retardation, and particularly in those who are severely or profoundly impaired, stereotyped behaviors are very common. Special educators do not typically get to watch the origin of these behaviors; rather, they are often confronted with well-developed behaviors which appear to be nonfunctional and can occur with such great frequency as to make training difficult. Sometimes these behaviors can be tied to environmental conditions or to schedules, as with Rushen’s (1984) sows.
Rates of stereotypies in persons with retardation have been found to vary with tempo of music (Stevens, 1971), amounts of toys and other objects in a room (Berkson, & Mason, 1963), the amount of noise in the environment (Forehand & Baumeister, 1971), levels of frustration (Hutt & Hutt, 1970), changes in ward personnel (Kaufman & Levitt, 1965), and the presence or absence of other individuals (Berkson & Mason, 1963).
Thelen (1981) noted that in autistic and retarded humans, as well as in chimpanzees, there seems to be a direct relationship between stereotypy and environmental complexity. Adams, et al. (1980), found that provision of a television in a living unit for mentally retarded adults caused increased stereotypy. Forehand & Baumeister (1981), on the other hand, found provision of color slides resulted in lower levels of stereotypic behavior than did no visual presentation. In the presumably more tightly controlled setting of Forehand & Baumeister, the visual stimuli were probably the most salient feature in the environment, whereas in the living unit of Adams et al., the television may have added to an already confusing and disturbing level of noise and visual stimuli.
Most early studies were somewhat descriptive, but stereotypic behavior, which some people consider to include self-injurious behaviors of various sorts, are a practical management problem in institutions for persons with mental retardation, and even early papers focused largely on behavior management. Although a great deal has been learned about the prevalence of various types of stereotypies in institutional settings and the efficacy of various behavioral methods of changing the frequency of apparently nonfunctional stereotypies, less is known about causal factors and almost nothing is known about the relationship between normal stereotypic behaviors such as the rhythmic behaviors of infants and the abnormal stereotypic behaviors of persons with mental retardation, the work of Berkson and Thelen being notable exceptions. A number of critical unanswered questions remain: (1) Are stereotyped behaviors which seem to be nonfunctional indeed nonfunctional, or they meet some need of the individual (1) What is the relationship between environmental complexity and abnormal stereotypic behaviors? What is the function of the state of arousal of the organism in regard to stereotypy? And (3) are individuals with abnormal stereotypic behaviors fixated as some developmental stage?
Comparisons of normal and abnormal rhythmic behaviors in normally developing and developmentally delayed humans and comparisons of rhythmic behaviors in human and non-human animals can be of great utility in unraveling the mystery of abnormal stereotypic behaviors. It seems likely that similar factors may be responsible for stereotypies across species. The animal literature shows clearly that small, bare enclosures and social deprivation can cause stereotyped behaviors, and that improvement of housing facilities and interaction with conspecifics can lead to reduction in rates and severity of stereotypies. Although it is not possible to do deprivation studies with humans, environmental factors are implicated in human stereotypies (Berkson, et al., 1985).
Further research in these areas may lead to increased understanding of the function and causal factors of abnormal stereotyped behaviors. This in turn may lead to practical ways of controlling these behaviors and increasing the quality of life in persons with mental retardation. More work of the caliber of Esther Thelen’s (1979, 1981), which integrated information from both non-human and human animals, and discussed both normal and abnormal behaviors, is especially needed.
References
Adams, G.L., Tallon, R.J., & Stangl, J.M. (1980). Environmental influences on self-stimulatory behavior. American Journal of Mental Deficiency, 85(2), 171-175.
Berkson, G., & Davenport, R.K. (1962). Stereotyped movements of mental defectives: I. Initial survey. American Journal of Mental Deficiency, 66(6), 849-852.
Berkson, G., & Mason, W.A. (1963). Stereotyped movements of mental defectives: III. Situation effects. American Journal of Mental Deficiency, 68, 409-412.
Berkson, G., McQuiston, S., Jacobson, J.W., Eyman, R., & Borthwick, S. (1985). The relationship between age and stereotyped behaviors. Mental Retardation, 23(1), 31-33.
Forehand, R., & Baumeister, A.A. (1976). Deceleration of aberrant behavior among retarded individuals. Progress in Behavior Modification, 2, 223-278.
Harlow, H.F. (1958). The nature of love. American Psychologist, 13, 673-685.
Harlow, H.F., & Harlow, M. (1962). Social deprivation in monkeys. Scientific American, 207(5), 137-146.
Hutt, C., & Hutt, J.S. (1970). Stereotypies and their relation to arousal: A study in autistic children. In S.J. Hutt & C. Hutt (Eds.), Behaviour studies in psychiatry. New York: Pergamon Press.
Kaufman, M.E., & Levitt, H. (1965). A study of three stereotyped and social behaviors in mental defectives. American Journal of Mental Deficiency, 69, 467-473.
Rushen, J. (1984). Stereotyped behaviour, adjunctive drinking, and the feeding period of tethered sows. Animal Behaviour, 32, 1059-1067.
Schwartz, S.S., Gallagher, P.J., & Berkson, G. (1984). Normal repetitive and abnormal stereotyped behaviors in infants and young children. Paper presented at the Eighteenth Annual Gatlinburg Conference on Research and Theory in Mental Retardation and Developmental Disabilities, Gatlinburg, TN, March, 1985.
Singer, P. (1975). Animal liberation: A new ethics for our treatment of animals. New York: Avon Books.
Stevens, E.A. (1971). Some effects of tempo changes on stereotyped rocking movements of low-level mentally retarded subjects. American Journal of Mental Deficiency, 76(1), 76-81.
Thelen, E. (1979). Rhythmical stereotypies in normal human infants. Animal Behaviour, 27, 699-715.
Thelen, E. (1981). Rhythmical behavior in infancy: An ethological perspective. Developmental Psychology, 17(3), 237-257.