LEARNING THEORY

Learning theory encapsulates two differing rationales to account for self-injurious behavior, regardless of whether the nature of the behavior is stereotyped or impulsive. These include (1) the positive reinforcement hypothesis, whereby self-injurious acts are performed to gain access to a preferred goal state, and (2) the negative reinforcement hypothesis, whereby self-injurious acts are engaged in order to escape an aversive condition. According to learning theory, a child or adolescent may engage in self-injurious behavior, such as stereotyped head banging or impulsive skin cutting, either to gain access to something that they experience as pleasant, such as social attention, which is contingent on performance of the self-injurious act (positive reinforcement), or to escape from something that they experience as unpleasant, such as social demands, suspension of which is contingent on performance of the self-injurious act (negative reinforcement). In either case, when self-injury results in access to a pleasant condition or facilitates escape from an unpleasant circumstance, the result is a strengthening (reinforcement) of the self-injurious behavior.

Self-injury in children and adolescents is a dramatic event that draws immediate attention and concern from adults. Parents, siblings, teachers, and friends, acting in good faith, may intuitively seek to provide comforting measures or modify and suspend limits or demands on a child or adolescent because it has the effect of stopping the self-injury, at least for the time being. In this regard, learning theory provides a useful insight as to how self-injury may be inadvertently reinforced and maintained by caretakers. Under certain circumstances, comforting measures intended to stop self-injury may result, paradoxically, in an increased frequency of the child’s self-injurious behavior because the child receives attention and caring after engaging in self-injury.^20a Similarly, modifying or eliminating expectations in response to a child’s self-injury also runs the risk of inadvertently teaching the child that self-injury is an effective way to communicate protest and to escape from nonpreferred tasks or stressful situations. The immediate effects of providing either comforting measures or “giving in” to the child’s protests quite often results in the temporary interruption of self-injurious behavior. In the long run, however, these approaches are likely to have the unintentional effect of promoting and strengthening self-injurious behavior and worsening the child’s problem.

SELF-REGULATORY (HOMEOSTATIC) THEORY

According to homeostatic theory, both stereotyped and impulsive self-injurious behaviors are considered self-stimulatory in nature and take the form of either arousal-inducing or arousal-reducing behaviors. In this perspective, when the optimal level of psychological stimulation is not available to a child, the child engages in compensatory activity, including self-injury, in an attempt to generate a more favorable or comfortable level of stimulation. Thus, the child is seen as self-regulating sensory stimulation by altering his or her level of arousal in relation to perceived changes in psychological stimuli. Underlying self-regulatory theory is the belief that children and adolescents (as well as adults) strive inherently to maintain a balanced level of central nervous system activation. That a certain degree of sensory stimulation is not only optimal, but also necessary, is a central tenet of the self-regulatory (homeostatic) hypothesis. Environmental sources of sensory stimulation, in the form of auditory, visual, tactile, vestibular, and kinesthetic modalities must be balanced and maintained at sufficient levels in order to avoid an internal sensation of discomfort. The same is true for cognitive and affective sources of sensory stimulation. According to self-regulatory theory, when the existing source of psychological stimulation does not fulfill the needs of the child, the underaroused child engages in self-injurious acts in an attempt to reach a balanced and sufficient level of sensory stimulation. Conversely, self-injurious acts also may function as self-stimulatory behaviors that regulate central nervous system activity when a child is overaroused. Engaging in proximal and monotonous self-injury is viewed as a means of effectively blocking potentially overwhelming psychological stimulation and achieving a lower and balanced arousal level.

The increased level of stereotyped self-injurious behavior displayed by children with autism spectrum disorder and mental retardation is hypothesized to be the result of striving to achieve this balance within a central nervous system that may be less reactive to distal environmental stimuli and more reactive to proximal stimulus conditions, because of the underlying nature of a developmental disability typified by cognitive deficit. This same self-regulatory hypothesis may be applied to adolescents with impulsive self-injury, who may experience underarousal or overarousal as a function of personality disorder or an affective illness, such as major depression, dysthymia, or bipolar disorder. When the adolescent’s internal balance of cognitive and/or affective sources of sensory stimulation is disrupted and he or she becomes either overaroused because of a perceived abundance of psychological stimulation or underaroused because of a perceived lack of stimulation, self-injurious behavior may serve a compensatory function and act to restore homeostasis.

DEVELOPMENTAL THEORY

According to developmental theory, self-injury is a unique subset of behaviors emerging from the larger category of repetitive behaviors commonly observed in infancy.²¹ In this regard, repetitive behavior is seen as occurring during the normal progression of early developmental stages and reflective of the child’s maturational process. Piaget²² viewed repetitive motor movements as reflecting the earliest stages of intellectual growth (i.e., sensorimotor period of development). For the infant, engaging in repetitive acts, or “circular reactions,” as Piaget termed them, emerges from an innate propensity for repetition, which allows infants to learn about their bodies. During the first year of life, the extent to which infants continue to engage in repetitive activity affects their ability to develop adaptive environment manipulation, which ultimately, helps them understand the world. Repetitive behavior would then decrease across the normal developmental trajectory as the child learns more adaptive and mature behavior, such as communication, to interact with the environment.

For children not progressing in accordance with the normal developmental trajectory, engaging in repetitive behavior was said to have become “fixated” at levels of primary and secondary circular reactions. Repetitive motor mannerisms directed toward the self were said to represent primary circular reactions, whereas repetitive motor mannerisms directed toward the environment were said to represent secondary circular reactions. Fixation, in this regard, was representative of not only a slower development but also a deceleration and termination of progress in the latter stages of the developmental period, in which continuing cognitive growth was anticipated. In sum, fixation was thought to occur when the course of normal development was disrupted as a result of inadequate learning experience, lack of appropriate stimuli, absence of critical role models, or physical and/or cognitive impairment.

Accordingly, self-injurious behavior is viewed as resulting from the stalling of an otherwise normal and transient stage of development. Repetitive self-injurious behavior has been observed in 5% of normally developing infants and toddlers before the age of 36 months,²³ usually in the form of head banging in the crib and usually with the clear communicative intent to be picked up, fed, burped, changed, or comforted because of sickness. The advent of language in the normally developing child results in no further self-injury. For children with autism spectrum disorder and mental retardation who fail to acquire language, repetitive self-injurious behavior becomes stereotypic in nature because of a “fixed primary circular reaction” based in earlier learning, in which it proved to be an efficacious means of communicating protest and discomfort and/or gaining access to care and comforting measures. It may be argued that this same line of reasoning, which overlaps extensively with the positive and negative reinforcement hypotheses of learning theory, may be applied to adolescents with impulsive self-injurious behavior and borderline personality disorder, in which a constant demand for attention is characteristic of the disorder, or those with affective disorder, in which the need to communicate distress and access safety and comforting measures may be paramount.

ORGANIC THEORY

According to organic theory, self-injurious behavior may be the product either of a genetic disorder or a nongenetic health condition. Smith-Magenis syndrome,²⁴ Lesch-Nyhan syndrome,²⁵ Prader-Willi syndrome,²⁶ Cornelia de Lange syndrome,²⁷ and Rett syndrome²⁸ are examples of mental retardation syndromes in which chronic self-injury is characteristic of the developmental disorder. A complex motor tic, such as self-slapping or skin picking, associated with Tourette syndrome²⁹ also is an example of a genetic disorder that may involve stereotyped self-injury. However, organic theory also allows for self-injurious behavior to occur as an artifact of a nongenetic health condition, such as epilepsy,³⁰ otitis media,³¹ headache, toothache and constipation,³² menstrual pain,³³ gastroesophageal reflux disease,³⁴ and sleep difficulties.³⁵ Children with autism spectrum disorders and mental retardation who are nonverbal and lack an effective means for communicating distress and illness may resort to self-injury in the form of repeatedly pressing or hitting an affected area possibly to achieve an anesthetic effect, or they may merely attack the affected area out of frustration over the discomfort it creates. Adolescents with personality disorder and/or affective illness also may experience an increased risk of impulsive self-injury as the result of an unrecognized health condition that produces pain, elevates discomfort, increases anxiety and agitation, or depresses mood. In this regard, they, too, may engage in self-injurious behavior in order to gain access to the “sense of relief” commonly reported to follow an episode of impulsive self-injury.

NEUROBIOLOGICAL THEORY

Research on the neurobiological mechanisms that underlie self-injurious behavior is an outgrowth of studies aimed at understanding why children with developmental disabilities engage in the larger class of stereotypic responding and, similarly, why adolescents with borderline personality disorder and comorbid affective disorder may experience an impulse to engage in self-injury. In this regard, the neurobiological perspective views dopaminergic, serotoninergic, and opioid mechanisms as playing a major role in the advent and maintenance of self-injurious behavior.

The dopamine hypothesis³⁶ is pursued largely because of the known association of alterations in basal ganglia dopamine with repetitive behaviors and the behavioral comparability of seemingly driven repetitive behavior with stereotypical and impulsive forms of self-injury. According to the dopamine hypothesis, self-injurious behavior results from a deficiency of dopamine that causes receptor sites to develop “supersensitivity” to the neurotransmitter, so that low levels of dopamine across the transmission sites create exaggerated excitability and result in basal ganglia dysfunction. Support for a dopamine hypothesis is derived from positron emission tomographic studies that demonstrate dopaminergic deficits associated with Lesch-Nyhan syndrome, a disorder characterized by stereotyped self-injury in the form of repetitive lip and finger biting. Additional support may be observed in studies of children with autism in which bromocriptine, a dopamine agonist, produced marked improvement in a variety of repetitive behavior disorders, as well as studies of so-called atypical antipsychotics, which block D₂ dopamine receptors and have been observed to be moderately effective in decreasing self-injury in children with developmental disabilities.

According to the serotoninergic hypothesis,³⁷ self-injurious behavior is caused by alterations in serotoninergic functioning that result in pathologically altered mood and, ultimately, failure of impulse control. Approximately 50% of adolescents with personality disorder and/or affective disorder admit to thinking about engaging in self-injury less than 1 hour before acting to cut or burn themselves. The serotonin hypothesis also gains support from findings that serotonin uptake inhibitors, such as clomipramine, have been demonstrated as a moderately effective treatment of self-injurious behavior. Additional support for a serotoninergic hypothesis is derived from studies that have shown increased self-injury after depletion or administration of selected precursors that act on serotoninergic neurotransmission.

The role of endogenous opiates³⁸ in self-injurious behavior is sought to explain both stereotyped and impulsive responding. In this regard, it has been hypothesized that for some children and adolescents, specifically, those with a demonstrated insensitivity to pain, self-injury may occur in response to a state of sensory depression brought about by chronic elevation of endogenous opiates. A second and more widely postulated theory suggests that some children with autism spectrum disorder and mental retardation may engage in stereotyped self-injurious behavior in order to gain access to endogenous opiates and, more specifically, to the favorable sensory consequence associated with its narcotic effect. This same line of reasoning may be applied to adolescents with borderline personality disorder or affective illness. Thus, gaining access to endogenous opiates through self-injury may, ironically, result in an improved sense of well-being. It is further speculated that the same children and adolescents may continue to hurt themselves, day after day, because they become addicted to the rewarding sensory consequence of the endorphins.

PSYCHODYNAMIC THEORY

Psychodynamic theory was formulated primarily as an attempt to explain impulsive self-injury in adolescent (and adult) populations with comorbid personality and affective disorders.³⁹ It is based on the self-disclosures of individuals with a history of self-injurious behavior and, to a greater extent, on the interpretation of these self-reports by professionals charged with providing treatment. Consequently, several hypotheses generated by psychodynamic theory cannot be empirically validated. However, many of the proposed causal mechanisms very clearly and extensively overlap with much of what has been previously reviewed with regard to learning, self-regulatory, developmental, organic, and neurobiological theories. In this regard, psychodynamic theory purports that children and adolescents engage in self-injury for a variety of reasons,⁴⁰ including (1) to gain access to care and comforting; (2) to distract themselves from emotional pain by causing physical pain; (3) to act as a compromise between life and death drives; (4) to punish themselves; (5) to relieve tension; (6) to feel “real” by feeling pain or seeing evidence of injury; (7) to end a dissociative episode; (8) to feel numb, “zoned out,” calm, or at peace; (9) to experience euphoric feelings; (10) to communicate their pain, anger, or other emotions to others; and (11) to nurture themselves through the process of the self-care of their wounds.