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Normal and Abnormal Stereotyped Behaviors in Humans and Infrahumans (1986)

Normal and Abnormal Stereotyped Behaviors in Humans and Infrahumans (1986)

©1986, 2013 by Dallas Denny

Source: Denny, Dallas. (1986). Normal and abnormal stereotyped behaviors in humans and infrahumans. Paper for Dr. Sid Levy, Special Education 3936, George Peabody College of Vanderbilt University.




Normal and Abnormal Stereotyped Behaviors

In Humans and Infrahumans


By Dallas Denny

For Dr. Sid Levy

Special Education 3936

April 19, 1986



All vertebrates exhibit rhythmic, repetitive behaviors. Some of these behaviors are normal and functional, but others are abnormal and non-functional. When the behaviors are abnormal, they are called stereotypies. Studies of normal rhythmic behaviors and abnormal stereotypies in both human and non-human animals are discussed. The importance of comparing normal and abnormal rhythmic behaviors in both human and non-human animals is stressed.

All vertebrates exhibit rhythmic, repetitive behaviors. They occur throughout ontogeny. Most of these behaviors are functional and some are quite necessary for the continuation of life. Locomotion, breathing, and eye-blinking, for example, are rhythmic behaviors. Sometimes, however, repetitive behaviors are non-functional or even deleterious. The terms stereotypic behavior and stereotyped behavior are commonly used to refer to non-functional rhythmic behaviors. These behaviors are sequences of motor acts which are relatively invariant, which are repeated frequently, and which have no apparent goal (Dawkins, 1980; Kiley-Worthington, 1977). They often occur with high frequency (Fentress, 1976). They occur in a wide range of species in an equally wide variety of behavioral contexts (Hediger, 1959; Hutt & Hutt, 1965 Pushen, 1984). The purpose of this paper is to examine findings about normal rhythmic behaviors and abnormal stereotyped behaviors in human and non-human animals.


Normal Rhythmic Behaviors in Developing Human Animals

Stereotypic behaviors are normal and important components of human behavior, especially during the first year of life (Kravitz & Boehm, 1971; Thelen, 1979, 1981). Attempts to explain this behavior from cognitive and psychodynamic points of view have been generally unfruitful. Piaget (1952) explained the movements as characteristic of a phase of “secondary circular reactions,” a developmental stage at which infants experiment upon the world. Other cognitive and psychodynamic explanations have focused upon pathology (cf Brody & Axelrad, 1979; and Leavy & Patrick, 1928). Spitz (1939) and Freud (1938) considered rhythmic behaviors of infants to be autoerotic. Anna Freud (1949) considered rhythmic behaviors to be self-directed aggression. Kravits & Boehm (1971) and Thelen (1981) more parsimoniously attributed the rhythmic behavior patterns of infants to normal motor development and the integration of simple repetitive patterns into voluntary motor patterns.

The topography and developmental history of rhythmical behaviors in normally developing infants was studied by Thelen (1979, 1981), who did an ethogram of the rhythmic behavior of normally developing infants. Thelen attacked the problem from a number of perspectives, using Tinbergen’s (1951) formulation to ask (1) “What is the immediate causal mechanism of the behavior?”; (2) “How did the child grow to respond in this particular way”; (3) “Why are stereotypic behaviors useful behaviors for a child to have?”; and (4) “What are the evolutionary origins of this behavior?” On the basis of observations of 16,000 bouts of stereotypic behavior, she was able to identify 47 distinct movements, including, kicking, rocking, waving, bouncing, scratching, banging, rubbing, thrusting, swaying, and twisting” (1981, p. 239). Many of the movements showed little variability, and fell well within the range of what ethologists called “fixed action patterns” (Tinbergen, 1951). She found the probability of different stereotypies varied with the age of the infant. Infants followed a clear developmental path, with behaviors emerging, peaking, and dropping out of the behavioral repertoire.

Thelen was able to identify antecedent environmental factors in 84% of the 16,000 bouts of stereotypy she observed. Most stereotypies seemed to be associated with a change of stimuli, for instance, appearance of a caretaker, or a change of state of arousal, for example, “fussiness” or drowsiness. She found the typical response to these apparent eliciting stimuli changed with age with, for instance, a younger infant engaging in a generalized increase in activity, and with older infants showing more specific responses, such as crawling and reaching movements. She noted that rhythmic movements have communicative effects; for instance, parents told her “That’s her angry kick.” She hypothesized that rhythmic movements can elicit increased attention from caregivers. The adaptive advantage to this is obvious. Thelen was able to test this hypothesis by showing 20-second videotapes of infants to mothers of preschool children and to college students. Soundtracks of a “fussy” infant were dubbed onto videos of infants who (1) showed no movement; (2) moved randomly; (3) kicked rhythmically for a few seconds or (4) kicked rhythmically throughout the presentation. Both groups of judges indicated that they would pick up the infant that kicked the most. Thelen also found that in different infants, percentage of time spent engaged in rhythmic activities ranged from about 5% to 40%. This was highly correlated with the amount of time the caregiver spent providing vestibular stimulation for the infant. “High stereotypy infants also were held less and talked to less and were more often placed in locations that restricted movements, such as infant seats and playpens” (1981, p. 242),

Stereotypic behavior in normal infants has been shown to vary with various aspects of the environment and with presumed internal states of the individuals involved. Thelen (1981), for example noted that “fussy” babies, and sometimes drowsy babies, showed higher rates of stereotypic behavior than did infants who were apparently content. Thelen also observed that infants who received high levels of vestibular stimulation from their caregivers engaged in rhythmic movements less often than did infants who received less stimulation.


Normal Rhythmic Behavior in Non-Human Animals

The concept of normal repetitive behaviors is integral to ethological theory:

Konrad Lorenz and Niko Tinbergen (1939) proposed that the nervous systems of animals must have special units responsible for the detection of neural messages generated by sign stimuli. These INNATE RELEASING MECHANISMS (IRM) would, upon receipt of the appropriate signal, activate a battery of motor cells and so turn on a behavioral response or FIXED ACTION PATTERN. Strictly speaking, a FAP is a motor response that can be performed in the absence of any guiding sensory feedback. Once released, the behavior is produced in its entirety without alteration, as if there was a programmed motor message to be played back in response to specific sensory signals… Although both the IRM and FAP are hypothetical constructs and have been modified in response to vigorous criticism over the years… there is growing evidence that there are physiological mechanisms that resemble IRMs and that generate FAPs.

                      —Alcock, 1979, p. 54

Fixed Action Patterns were devised to explain behaviors such as egg-rolling in geese. If an egg rolls out of the nest of a greylag goose, the goose retrieves it by stretching the neck towards it, bringing the bill behind the egg and with careful balancing movements rolling it back in to the nest (Tinbergen, 1951, p. 84). Once the retrieval movement is initiated, it apparently cannot be stopped. The goose will continue the behavior even if the egg is removed during the middle of the retrieval process. Because eggs are oval, they do not roll smoothly, and the goose makes compensating movements to the left and right to keep the egg centered. The left and right compensating movements are not shown after the egg is removed.

FAPs are also called species-typical stereotyped motor patterns (Brown, 1975). They occur in many diverse species, and in many contexts. They are usually repetitive in nature. The topography and timing of the movements are very consistent. Examples of FAPs include the head-bobbing displays of Anolis lizards (Jenssen, 1980) and the courtship display of crickets (Bentley & Hoy, 1974). Examples of FAPs are scattered widely throughout the ethological literature.

Brown (1975) has characterized seven characteristics of FAPs. Most notably, they occur in all individuals of a species, do not rely upon learning, and are subject to genetic manipulation. They differ from reflexes in that whereas reflexes are integrative units which bring about relationships between certain stimuli and certain responses, FAPs are units of motor coordination. Study of neuronal mechanisms of FAPs is a serious topic of study for ethologists.


Abnormal Stereotypic Behavior In Non-human Animals

In animals, stereotypies have been shown to vary with changes in the environment and with presumed internal states. Stereotyped behavior is common in animals raised in captivity (Fox, 1968). Even though housing conditions in zoos have improved considerably in recent years, a trip to any zoo will show many animals engaging in stereotypic pacing. Meyer-Holzapfel (1968) described these pacing movements, as well as rhythmic swinging of the head and rumination. I observed an adult polar bear engaging in a stereotyped swimming pattern at the Knoxville Zoo during the summer of 1984. Meyer-Holzapfel (1968) mentioned that abnormal movements are most common in small enclosures where the natural movements of the animal are restrained, and that such stereotypies often disappear with changes in the enclosure.

Peter Singer (1975) has described the appalling conditions in which animals are raised in factory farms. Many animals spend their entire lives in tiny pens which allow no semblance of a normal life. Abnormal behavior is common in farm animals which spent large amounts of time in such enclosures. Rushen (1984) found tethered sows showed certain stereotypies directly before and directly after mealtimes. Other stereotypies did not seem to vary predictably with mealtimes. Behaviors which did seem to be associated with mealtimes were to some extent topographically similar to the natural food-seeking behavior of this species (e.g. movements of the forelimbs and snout). Rushen noted that the topography of the stereotypic behaviors did vary somewhat from actual food-seeking behaviors in pigs; this may have been due, however, to the concrete floor and to the confines of the small artificial enclosure in which the sows were housed. Since the pigs were fed daily at the same time, and since a cart was noisily pushed around the piggery, there was a possibility that either (1) the behaviors were schedule induced); or (2) the behaviors were classically conditioned responses. Similar behaviors, for example crib-biting, have been observed to occur in other farm animals (Fraser, 1968).

Stereotyped behaviors are also observed in pet animals. On several occasions I observed stereotyped eye-gouging in a large parrot at a pet store in Hillsboro Village in Nashville. This parrot reached around its head with its leg and placed a claw in its eye socket. Pet store personnel informed me the bird had engaged in the behavior for a number of years. And it is a rare person who has not been annoyed by a dog which barks all night.

The classic deprivation studies which were carried out in the 1950’s by Harry Harlow and his associates (1958, 1962), and which have been extensively replicated, produced abnormal stereotypic behaviors in rhesus monkeys and other primates which were reared in isolation from their mothers and/or from other monkeys. These monkeys were extremely poorly socialized, and engaged in high rates of body rocking, nonnutritive sucking, and other stereotypic behaviors. Monkeys showed a total of about five abnormal stereotypies, whereas chimpanzees showed at least 25. It must be understood these deprived primates were highly abnormal individuals and their stereotypies were extremely pathological behaviors. Stereotypies seem to be extremely rare or nonexistent in monkeys and apes in naturalistic settings (Thelen, 1981). An exception was reported by Chevalier-Skolnikoff (1976, 1977) who reported stereotypic behavior in gorillas.

In a deprivation study reminiscent of the Harlows’, Mason & Berkson (1975) found rhesus monkeys which were reared on artificial mothers which were mechanically moved about in the environment did not develop stereotyped body rocking. Control monkeys had a mother which was not moved about, and did develop body rocking. Harlow (1958) found monkeys reared with a cloth-covered artificial mother seemed more self-assured and engaged in fewer stereotypies than did monkeys raised on wire-covered artificial mothers.

Skinner (1948) reported that pigeons in operant conditioning chambers on a random schedule of reinforcement often developed stereotyped behaviors. Skinner called these behaviors superstitious behavior. They are apparently formed by reinforcement of behaviors which happen to be occurring when food is provided. Although the provision of the food is not contingent upon the behavior, the pigeon acts as if it were. It is unclear to what extent superstitious behavior causes stereotypies. It is of especial note that animals in small enclosures (much like the pigeon) show high rates of ritualized behaviors; some of these behaviors may be caused the same way as superstitious behavior in the pigeon.


Abnormal Stereotypic Behavior in Human Animals

In humans, most stereotypic behaviors occur in handicapped individuals. In developmentally handicapped persons, stereotypic behavior is often called self-stimulatory behavior (Adams. Tallon, & Stangl. 1980; Harris & Wolchik, 1979). Self-injurious behavior is often topographically similar to stereotypic behavior, but is generally treated separately in the literature, even though it is unclear whether causal factors are the same for self-stimulatory and self-injurious behaviors. The incidence of stereotypy among mentally retarded individuals has been studied, especially in residential institutions; the majority of institutionalized mentally retarded persons show some type of stereotypy (Adams, et al., 1980; Berkson & Davenport, 1962; Kaufman & Levitt. 1965; Tierney. et al., 1979), and stereotypy is one of the defining characteristics of autism (Rimland, 1964). Stereotypies are considered undesirable, both inside and outside of the institution, because they are unattractive (Harris & Wolchik, 1979) and may interfere with learning (Forehand & Baumeister, 1976; Kaufman & Levitt, 1965). Therefore, a number of techniques have been used to reduce stereotypies in institutionalized retarded and autistic individuals.

The most successful methods of reducing stereotypic behaviors have been reported in the literature of applied behavior analysis. These methods have included administration of psychoactive drugs, contingent vibration, overcorrection, time-out, differential reinforcement of other behavior, contingent administration of noxious liquids, positive reinforcement, extinction, facial screening, differential reinforcement of incompatible behavior, response-cost procedures, and electric shock (cf Forehand & Baumeister, 1976, for a review).

The development and topography of stereotypic behaviors in developmentally delayed persons is not well known. Most workers agree on the types of stereotypies most frequently exhibited by institutionalized persons, but have rarely described adequately the topography of stereotypic behaviors. An ethogram such as Thelen’s (1979, 1981) of stereotypic behavior in normal children is needed. Body rocking, swaying, head shaking, hand waving, twirling, “pill rolling,” mouthing, and shaking of objects are frequently mentioned in the literature (cf Berkson & Davenport, 1962; Kaufman & Levitt, 1965; & Stevens, 1971). Typically, the behavior is described with a short phrase, for instance, as “body rocking” (Tierney, et al., 1979). Often, an attempt is made to operationally define the stereotypy, as with Stevens (1971):

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)

Kravitz & Boehm (1971) observed normal and handicapped neonates in a hospital. They noted that infants with Down syndrome or cerebral palsy showed a marked delay in the onset of rhythmic motor patterns. Recently, Berkson and his colleagues (Schwartz, Gallagher, & Berkson, 1985) have begun to examine the origin and topography of repetitive behavior in severely mentally retarded young children. They have found topographic differences between the body rocking and hand gazing behaviors of normal infants and retarded children. Retarded children look at their hands longer than normal infants, and engage in repetitious movements of the hands while doing so; normal infants do not. Also, retarded children gaze at their hands in several different body positions, while normal infants gaze at their hands only while in a supine position. The body rocks of retarded children have a greater amplitude than do the body rocks of normal infants; additionally, the retarded children rock for longer periods of time.

Berkson, McQuiston, Jacobson, Eyman. and Borthwlck (1985) reported a low rate of abnormal stereotypic behavior in institutionalized retarded children. The rate increased rapidly with age, peaked at the onset of adulthood, and then slowly decreased.

Some stereotypies in institutionalized mentally retarded persons seem to vary with provision of meals (Kaufman & Levitt, 1965). As with pigs, the effects may be due to classical conditioning and scheduled-induced effects.

A number of researchers have observed the effect of administration of psychoactive drugs upon the stereotypies of institutionalized individuals. Not surprisingly, findings have varied With drugs administered. For instance, Berkson (1965) found no effect on stereotypies with two levels of an amphetamine, two levels of a central nervous system depressant, and a placebo. Davis, Sprague, & Werry (1968) found an effect with Thorazine.

Rates of stereotypies have also been found to vary with changes of tempo of music (Stevens, 1971), amount of toys and other objects in a room (Berkson & Mason, 1963), the amount of noise in the environment, levels of frustration (Forehand & Baumeister, 1971; Hutt & Hutt, 1970), changes in ward personnel (Kaufman & Levitt, 1965), and the presence or absence of other individuals (Berkson & Mason, 1963). Some stereotypies may vary cyclically. Lewis, MacLean, Johnson, & Baumeister (1981) found institutionalized mentally retarded persons showed variable frequency of stereotypic behavior, with a period of about four hours.

Thelen (1981) noted that in autistic and retarded humans, as well as in chimpanzees. there seems to be a direct relationship between stereotypy and arousal and an inverse relationship between stereotypy and environmental complexity. Adams, et al. (1980) found provision of a television in a living unit for mentally retarded adults caused increased stereotypy. Forehand and Baumeister (1971), on the other hand, found provision of color slides resulted in lower levels of stereotypy than did no visual presentation. In the presumably more tightly controlled setting of Forehand & Baumeister, the visual stimuli were probably the most predominant feature, whereas in the living unit of Adams, et al. (1980), the television may have added to an already confusing and disturbing level of noise and visual stimuli.



During the past twenty years, the majority of papers published about stereotypic behavior in humans have been reports of attempts to reduce the frequency of abnormal behaviors, or reviews of such attempts. Although a good 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 abnormal 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 abnormal stereotypic behaviors of handicapped persons. A number of critical unanswered questions remain:

(1) Are stereotypic behaviors which seem to be nonfunctional indeed functional? Do they meet some need of the individual?


(2) What is the relationship between environmental complexity and abnormal stereotypic behaviors? What is the function of the state of arousal of the organism and stereotypy?


and (3) Are individuals with abnormal stereotypic behaviors fixated at some developmental stage?

Comparisons of normal and abnormal rhythmic behaviors 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 similar factors may be responsible for stereotypies in both humans and non-humans. The animal literature shows clearly small enclosures in particular can cause stereotyped behaviors, and improvement of facilities can lead to reductions in stereotyped behaviors, but severe deprivation can lead to poor socialization and irreversible deficits In behavior. Although it is not possible to do deprivation studies with humans, environmental factors are implicated in human stereotypies (Berkson. et al., 1985). Also, low levels of vestibular stimulation may result in high levels of stereotypies in both humans and non-humans. Further research in both of these areas may lead to increased understanding of the function and causal factors of abnormal stereotyped behaviors. Increased understanding of abnormal stereotypies may lead to practical ways of controlling these behaviors and increasing the quality of life of handicapped persons. More work of the caliber of Esther Thelen’s, which integrated information from both non-human and human animals, and discussed both normal and abnormal behaviors, is especially needed.




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