Behavioral variability and autism spectrum disorder

No differences in implicit hand maps among different degrees of autistic traits

People with autism spectrum disorder (ASD) or higher levels of autistic traits have atypical characteristics in sensory processing. Atypicalities have been reported for proprioceptive judgments, which are tightly related to internal bodily representations underlying position sense. However, no research has directly investigated whether self-bodily representations are different in individuals with ASD. Implicit hand maps, estimated based on participants' proprioceptive sensations without sight of their hand, are known to be distorted such that the shape is stretched along the medio-lateral hand axis even for neurotypical participants. Here, with the view of ASD as falling on a continuous distribution among the general population, we explored differences in implicit body representations along with autistic traits by focusing on relationships between autistic traits and the magnitudes of the distortions in implicit hand maps (N ~ 100). We estimated the magnitudes of distortions in implicit hand maps both for fingers and hand surfaces on the dorsal and palmar sides of the hand. Autistic traits were measured by questionnaires (Autism Spectrum [AQ] and Empathy/Systemizing [EQ-SQ] Quotients). The distortions in implicit hand maps were replicated in our experimental situations. However, there were no significant relationships between autistic traits and the magnitudes of the distortions as well as within-individual variabilities in the maps and localization performances. Consistent results were observed from comparisons between IQ-matched samples of people with and without a diagnosis of ASD. Our findings suggest that there exist perceptual and neural processes for implicit body representations underlying position sense consistent across levels of autistic traits.

Effects of variability requirements on difficult sequence learning

The present study investigated the effects of variability requirements on learning difficult target sequences in humans. Twenty university students emitted five-response sequences. For the experimental groups, 30 nontarget sequences were reinforced according to the Lag-10 variation criterion or the Lag-3 repetition criterion across conditions. For the control groups, the probability of reinforcers for nontarget sequences was yoked to that obtained by the experimental groups. In addition, for both groups, two difficult target sequences were continuously reinforced. U values were higher with the Lag-10 variation criterion than with the Lag-3 repetition criterion for the experimental groups and were unsystematic for the control groups. Higher U values ​​were accompanied by a random pattern in the emission of nontarget sequences for all groups. Higher levels of variability, regardless of whether they were directly produced by reinforcement or were contingency induced, facilitated learning of difficult target sequences.

Reinforced behavioral variability in the valproate rat model of autism spectrum disorder

Individuals diagnosed with autism spectrum disorder (ASD) tend to display restricted, repetitive behaviors and deficits in social interaction. Rats exposed to valproate (VPA) in utero have been shown to model symptoms of ASD. In previous research, VPA rats engaged in less social interaction and more repetitive responding than controls. The purpose of the present study was to further investigate behavioral variability in the VPA rat model of ASD by testing VPA and control rats in a reinforced-behavioral-variability operant task. In this procedure, rats emitted sequences of lever presses, some of which produced food. During baseline, food was delivered probabilistically, and variability was not required. Next, rats were exposed either to a variability contingency, in which food was only delivered following sequences that differed sufficiently from previous sequences (i.e., variability required), or to a yoked contingency, in which variability was not required. We hypothesized that VPA rats would behave less variably than controls in this task. However, VPA and control rats responded similarly variably when variability was required. Furthermore, VPA rats behaved slightly more variably than controls during baseline and yoked conditions, when variability was not required. These findings contribute to the complex literature surrounding the VPA rat model of ASD.

A translational evaluation of listener interest on the presentation of conversation topics to individuals who exhibit restricted interests

Listener behavior has been shown to influence speaker behavior. However, little is known about the extent to which listener behavior can influence countertherapeutic outcomes. This study evaluated the influence of listener interest on the topics presented by adult participants conversing with an experimenter acting as an individual who exhibited restricted interests. Each session consisted of a 5‐min conversation, during which the participant was instructed to talk about 3 topics. We compared the duration of topic presentation across phases in which the experimenter behaved as an interested listener for 1 topic or for all 3 topics. Results showed that topic presentation was controlled by listener interest and all participants reported that the simulation was believable, acceptable, and useful. Although preliminary, these findings have implications for understanding possible undesirable interactions between individuals diagnosed with autism spectrum disorder who exhibit restricted interests and their peers or caregivers.

Some Dimensions of Mand Variability and Implications for Research and Practice

Since Skinner's conceptualization of the mand, applied behavior analysis researchers have used the concept to develop stimulus control transfer procedures effective for addressing manding deficits. More recently, researchers have explored the clinical utility of reinforcing mand variability during mand training and functional communication training. However, limitations in the conceptual analysis of mand variability may have limited the kinds of questions addressed in this research and our understanding of the findings. The current article reconceptualizes mand variability as consisting of eight distinct dimensions and provides operational definitions of the dimensions that may be useful for more precisely characterizing the effects of reinforcement on mand variability in future research. The article concludes with a brief discussion of potential clinical and research implications.

A Psychometric Evaluation of the Quality of Life for Children with Autism Spectrum Disorder Scale

Our purpose in this study was to validate the Quality of Life for Children with Autism Spectrum Disorder scale. We first conducted an exploratory factor analysis to examine the factor structure. Results suggested that a three-factor model (Interpersonal Relationships, Self-Determination, and Emotional Well-Being) should be retained. Next, we conducted a confirmatory factor analysis to compare a higher-order factor model and additional models. Results showed acceptable model fit for the higher-order factor model. The scale had excellent reliability (α = .90) for the overall scale and for the three subscales (Interpersonal Relationships, α = .87; Self-Determination, α = .81; and Emotional Well-Being, α = .66). The 16-item scale showed convergent and divergent validity. Implications for future research and practice are discussed.

A Critical Review of the Support for Variability as an Operant Dimension

There is abundant evidence that behavioral variability is more predominant when reinforcement is contingent on it than when it is not, and the interpretation of direct reinforcement of variability suggested by Page and Neuringer, Journal of Experimental Psychology: Animal Behavior Processes, 11(3), 429-452 (1985) has been widely accepted. Even so, trying to identify the underlying mechanisms in the emergence of stochastic-like variability in a variability contingency is intricate. There are several challenges to characterizing variability as directly reinforced, most notably because reinforcement traditionally has been found to produce repetitive responding, but also because directly reinforced variability does not always relate to independent variables the same way as more commonly studied repetitive responding does. The challenging findings in variability experiments are discussed, along with alternative hypotheses on how variability contingencies may engender the high variability that they undeniably do. We suggest that the typical increase in behavioral variability that is often demonstrated when reinforcement is contingent on it may be better explained in terms of a dynamic interaction of reinforcement and extinction working on several specific responses rather than as directly reinforced.

Sensitivity to Changing Environmental Conditions across Individuals with Subtype 2 Automatically Reinforced and Socially Reinforced Self-injury

Automatically reinforced Subtype 2 self-injurious behavior (ASIB) has been characterized as showing insensitivity to competing reinforcement contingencies in the contexts of both functional analyses and in treatment using reinforcement alone (Hagopian, Rooker, &Yenokyan, 2018). One question is whether this insensitivity is specific to Subtype 2 ASIB as response class in these contexts or whether it is represents a generalized response tendency of the individual that is evident across other response classes. To examine this question, we compared responding on a single-operant task under changing reinforcement schedules for three individuals with Subtype 2 ASIB, relative to a comparison group of three individuals with socially reinforced SIB (which is characterized by sensitivity to changes in reinforcement contingencies). As hypothesized, all individuals showed sensitivity to changes in contingencies. These results provide preliminary support that the insensitivity of Subtype 2 ASIB is a property specific to that response class in these contexts rather than a generalized response tendency of the individual.

Choice for reinforced behavioral variability in children with autism spectrum disorder

Although individuals with autism spectrum disorder (ASD) tend to behave repetitively, certain reinforcement contingencies (e.g., lag schedules) can be used to increase behavioral variability. In a lag schedule, reinforcers only follow responses that differ from recent responses. The present study was designed to promote variable play behavior in preschoolers with ASD interacting with playsets and figurines and to assess preference for variability and repetition contingencies. Data have shown a preference for variability in pigeons and college students, but this effect has not been explored in clinical populations. In this experiment, preschoolers with ASD were taught to discriminate between variability and repetition contingencies. Only play behaviors that met a lag schedule were reinforced in the presence of one color, and only repetitive behaviors were reinforced in the presence of another. After differential performance was established, participants experienced a concurrent chains schedule. Participants chose between the colors taught in training and then completed a play session with the selected contingency. One participant selected variability and repetition equally. The other participants showed a slight preference for variability. These results indicate that some individuals with ASD may play repetitively, not because they prefer repetition, but because they require additional teaching to play variably.

The Effects of Scenic Picture Prompts on Variability During the Acquisition of Intraverbal Categorization for Children With Autism

Researchers have demonstrated the efficacy of picture prompts on the acquisition of intraverbals (Coon & Miguel in Journal of Applied Behavior Analysis, 45, 657-666, 2012; Goldsmith, LeBlanc, & Sautter in Research in Autism Spectrum Disorders, 1, 1-13, 2007; Ingvarsson & Hollobaugh in Journal of Applied Behavior Analysis, 44, 659-664, 2011; Ingvarsson & Le in The Analysis of Verbal Behavior, 27, 75-93, 2011; Miguel, Petursdottir, & Carr in The Analysis of Verbal Behavior, 21, 27-41, 2005; Partington & Bailey in The Analysis of Verbal Behavior, 11, 9-18, 1993). However, no one (to our knowledge) has determined the effects of picture prompts on the variability of responding during intraverbal categorization. We evaluated the use of a scenic picture prompt on response variability during the acquisition of intraverbal categorization with 4 children diagnosed with autism. All children mastered the task and initially demonstrated varied responding. However, responding eventually became invariant for all children. These results demonstrate the efficacy of a scenic picture prompt for teaching children with autism intraverbal categorization and for producing initial response variability. Additional research should be conducted to determine teaching procedures that promote continued varied responding for individuals with autism.

Increasing Response Diversity to Intraverbals in Children with Autism Spectrum Disorder

The purpose of this study was to evaluate the effects of intraverbal prompts on response diversity and novelty in intraverbals posed to children with autism spectrum disorder (ASD). The intraverbal prompts involving function, feature, and class (FFC) of an item were used in the training of three questions requiring multiple responses. Two Chinese boys with ASD (aged 5-6 years) served as participants. A multiple-probe across three behaviors design was employed. The results indicated that the intraverbal prompts effectively increased the number of divergent responses to all three questions. Novel responses emerged at a low level while generalization to similar questions was not observed following the training.

Views of professionals about the educational needs of children with neurodevelopmental disorders

BACKGROUND

Professionals play a key role in supporting children with special educational needs in schools. However, the views of those working with neurodevelopmental disorders are less known.

AIMS

This study examined the views of professionals (including teachers, teaching assistants, educational psychologists, speech and language therapists, physio and occupational therapists etc.) working with children with Williams Syndrome (WS), Down Syndrome (DS) or with Autism Spectrum Disorders (ASD) in terms of how informed professionals are about the disorder and their views about the type of support these children need to be receiving.

METHODS AND PROCEDURES

Professionals working with 77 children with ASD, 26 with DS and 38 with WS completed an online questionnaire.

OUTCOMES AND RESULTS

Professionals in all three groups highlighted relevant areas of difficulty for these children, but they did not recognise some of the less phenotypical difficulties that children with a specific disorder may experience. In addition, there was a disconnect between the difficulties identified by the professionals and the type of specialist support that may be necessary.

CONCLUSIONS AND IMPLICATIONS

Although professionals have a lot of knowledge about the specific neurodevelopmental disorders, further evidence-based training would allow more effective support for children with neurodevelopmental disorders in the classroom but also equip professionals better and raise their confidence in meeting these children's needs.

A Systematic Review of Interventions to Promote Varied Social-Communication Behavior in Individuals With Autism Spectrum Disorder

Individuals with autism spectrum disorder (ASD) may engage in repetitive social-communication behaviors that can limit their skill acquisition, access to reinforcement, and access to less restrictive settings. Basic and applied research indicates that variability, or the extent to which responses are topographically different from one another, is influenced by antecedent and consequence interventions. Our purpose in this study is to systematically review the literature on interventions to increase variable social-communication behaviors in individuals with ASD. We identified 32 studies through a database search and screened them using the What Works Clearinghouse (WWC) Single-Case Design Standards. Eighteen studies containing 55 cases met WWC Design Standards. We coded the descriptive characteristics and strength of evidence based on visual analysis from each of these 18 studies and calculated effect sizes using Tau-U. Our results indicate that most cases (65%) provide strong evidence of a functional relation between the interventions and varied social-communication behaviors, and the median Tau-U was .82. We discuss the implications of our results for practice and for future research on interventions designed to increase variability with this population.

An Evaluation of the Effects of Varying Magnitudes of Reinforcement on Variable Responding Exhibited by Individuals With Autism

Interventions aimed at increasing communicative response variability hold particular importance for individuals with autism spectrum disorders (ASD). Several procedures have been demonstrated in the applied and translational literature to increase response variability. However, little is known about the relationship between reinforcer magnitude and response variability. In the basic literature, Doughty, Giorno, and Miller evaluated the effects of reinforcer magnitude on behavioral variability by manipulating reinforcer magnitude across alternating relative frequency threshold contingencies, with results suggesting that larger reinforcers induced repetitive responding. The purpose of this study was to translate Doughty et al.'s findings to evaluate the relative effects of different magnitudes of reinforcement on communicative response variability in children with ASD. A Lag 1 schedule of reinforcement was in place during each condition within an alternating treatments design. Magnitudes of reinforcement contingent on variable communicative responding were manipulated across the two conditions. Inconsistent with basic findings, the results showed higher levels of variable communicative responding associated with the larger magnitude of reinforcement. These outcomes may have potential implications for interventions aimed at increasing response variability in individuals with ASD, as well as future research in this area.

Effects of a Lag Schedule with Progressive Time Delay on Sign Mand Variability in a Boy with Autism

For some children with autism, mand training can produce highly repetitive manding unless the environment is arranged in a manner that promotes mand variability. Prior research demonstrated that mand training using a lag schedule and progressive time delay increased variability in vocal manding in children with autism. Whether lag schedules have similar effects on sign mand topographies is unknown. The current study evaluated the effects of mand training with a Lag 1 schedule of reinforcement and progressive time delay (TD) on topographical variability and the development of a sign mand response class hierarchy in a boy with autism. The results suggest independent use of all sign mand topographies occurred, a mand response class hierarchy was developed, and topographically variant sign manding increased under the Lag 1 + TD schedule compared to a Lag 0 schedule of reinforcement. Implications for practitioners, limitations, and directions for future research are discussed.

Effects of modeling rote versus varied responses on response variability and skill acquisition during discrete-trial instruction

Despite its advantages, discrete-trial instruction (DTI) has been criticized for producing rote responding. Although there is little research supporting this claim, if true, this may be problematic given the propensity of children with autism to engage in restricted and repetitive behavior. One feature that is common in DTI that may contribute to rote responding is the prompting and reinforcement of one correct response per discriminative stimulus. To evaluate the potential negative effects of rote prompts on varied responding, we compared the effects of modeling rote versus varied target responses during the teaching of intraverbal categorization. We also evaluated the effects of these procedures on the efficiency of acquisition of any one correct response. For all four children, any increase in varied responding was fleeting, and for two participants, acquisition was slower in the variable-modeling condition.

Increased scale-free dynamics in salience network in adult high-functioning autism

Autism spectrum disorder (ASD) is clinically characterized by extremely slow and inflexible behavior. The neuronal mechanisms of these symptoms remain unclear though. Using fMRI, we investigate the resting state's temporal structure in the frequency domain (scale-free activity as measured with Power-Law Exponent, PLE, and Spectral Entropy, SE) and temporal variance (neural variability) in high-functioning, adult ASD comparing them with schizophrenic and neurotypical subjects. We show that ASD is characterized by high PLE in salience network, especially in dorsal anterior cingulate. This increase in PLE was 1) specific for salience network; 2) independent of other measures such as neuronal variability/SD and functional connectivity, which did not show any significant difference; 3) detected in two independent samples of ASD but not in the schizophrenia sample. Among salience network subregions, dorsal anterior cingulate cortex exhibited PLE differences between ASD and neurotypicals in both samples, showing high robustness in ROC curves values. Salience network abnormal temporal structure was confirmed by SE, which was strongly anticorrelated with PLE and thus decreased in ASD. Taken together, our findings show abnormal temporal structure (but normal temporal variance) in resting state salience network in adult high-functioning ASD. The abnormally high PLE indicates a relative predominance of slower over faster frequencies, which may underlie the slow adaptation to unexpected changes and the inflexible behavior observed in autistic individuals. The specificity of abnormal PLE in salience network suggests its potential utility as biomarker in ASD.

An evaluation of lag schedules and prompting methods to increase variability of naming category items in children with autism spectrum disorder

A lag schedule of reinforcement is one way to increase response variability; however, previous research has been mixed with regard to the necessary parameters to increase variability. For some individuals, low schedule requirements (e.g., Lag 1) are sufficient to increase variability. For other individuals, higher lag schedules (e.g., Lag 3) or a lag schedule in combination with prompting is needed to increase variability. We evaluated the efficiency of different within-session progressive lag schedules to increase response variability with 2 children with autism. Results showed that increasing the lag criterion across sessions increased variability to levels similar to beginning with a high lag schedule for one participant. When lag schedules did not increase variability for the second participant, we compared a variety of prompting procedures. Results of the prompting evaluation showed that a tact-priming procedure was effective to increase varied responding.

Effects of a lag schedule of reinforcement with progressive time delay on topographical mand variability in children with autism

OBJECTIVE

Evaluate the effects of a Lag 1 schedule of reinforcement and progressive time delay (TD) on topographical mand variability in children with autism.

METHODS

Using single-subject design methodology, a multiple baseline across behaviors with embedded reversal design was employed. During Lag 0, reinforcement was delivered contingent on any independent instances of manding. During Lag 1 + TD, prompts were faded and reinforcement was delivered contingent on independent or prompted variant mand topographies.

RESULTS

Higher levels of topographical mand variability were observed during Lag 1 + TD for both participants.

CONCLUSIONS

A Lag 1 schedule of reinforcement with progressive TD increased variability across functionally equivalent vocal mand topographies for both participants. This finding extends prior literature by providing a novel model for studying reinforced mand variability in children, and by demonstrating how practitioners could use prompts and differential reinforcement to increase topographical mand variability in children with autism.

Increasing "Object-Substitution" Symbolic Play in Young Children With Autism Spectrum Disorders

Children with autism spectrum disorders (ASD) may not develop symbolic play skills, so such skills need to be taught specifically. We report an experiment regarding a procedure targeting "object-substitution" symbolic play skills. The "object-substitution" symbolic play behavior occurred when the child labeled a common object with the name of a substitute and used the object to perform a play action (e.g., As she put a bowl on her head, she called it a hat). A multiple probe across behaviors design was employed with five children (four boys and one girl, aged 3 to 6 years) with ASD. All children had verbal communication and demonstrated functional play and generalized imitation, but no symbolic play skills prior to the study. The instruction consisted of intraverbal training, picture prompts, and modeling of play actions. All children demonstrated object-substitution symbolic play skills after the instruction. The occurrences of response generalization were also discussed.

An Evaluation of Lag Schedules of Reinforcement During Functional Communication Training: Effects on Varied Mand Responding and Challenging Behavior

We evaluated the effects of lag schedules of reinforcement during functional communication training (FCT) on the varied use of mands and challenging behavior by two individuals diagnosed with autism. Specifically, we compared the effects of Lag 0 and Lag 1 schedules of reinforcement during FCT. The results showed that each participant exhibited increases in varied mand responding during FCT with the Lag 1 schedule of reinforcement relative to Lag 0; challenging behavior remained low during both FCT lag conditions relative to baseline. Results are discussed in terms of treatment implications relating to FCT and the potential prevention and/or mitigation of clinical relapse during challenges to treatment.

Translational evaluation of a lag schedule and variability in food consumed by a boy with autism and food selectivity

PURPOSE

To evaluate the effects of a lag schedule of positive reinforcement on variability in food consumed by a boy with autism and food selectivity.

METHODS

Using single-subject experimental design methodology, an ABAB design was employed. During lag 0 (condition A), high-preferred toys were delivered contingent on consumption of any food. During lag 1 (condition B), high-preferred toys were delivered contingent on consumption of different foods within session.

RESULTS

Higher levels of variability in within-session consumption were observed during lag 1 conditions.

CONCLUSIONS

The lag 1 schedule of reinforcement increased variability in food consumed. This finding adds to the literature by demonstrating a novel experimental arrangement that may be used in applied studies to evaluate the clinical utility of differentially reinforcing variability in the treatment of food selectivity associated with autism.

Reversal learning in C58 mice: Modeling higher order repetitive behavior

Restricted, repetitive behaviors are diagnostic for autism and prevalent in other neurodevelopmental disorders. These behaviors cluster as repetitive sensory-motor behaviors and behaviors reflecting resistance to change. The C58 mouse strain is a promising model for these behaviors as it emits high rates of aberrant repetitive sensory-motor behaviors. The purpose of the present study was to extend characterization of the C58 model to resistance to change. This was done by comparing C58 to C57BL/6 mice on a reversal learning task under either a 100% or 80%/20% probabilistic reinforcement schedule. In addition, the effect of environmental enrichment on performance of this task was assessed as this rearing condition markedly reduces repetitive sensory-motor behavior in C58 mice. Little difference was observed between C58 and control mice under a 100% schedule of reinforcement. The 80%/20% probabilistic schedule of reinforcement generated substantial strain differences, however. Importantly, no strain difference was observed in acquisition, but C58 mice were markedly impaired in their ability to reverse their pattern of responding from the previously high density reinforcement side. Environmental enrichment did not impact acquisition under the probabilistic reinforcement schedule, but enriched C58 mice performed significantly better than standard housed C58 mice in reversal learning. Thus, C58 mice exhibit behaviors that reflect both repetitive sensory motor behaviors as well as behavior that reflects resistance to change. Moreover, both clusters of repetitive behavior were attenuated by environmental enrichment. Such findings, along with the reported social deficits in C58 mice, increase the translational value of this mouse model to autism.

An analysis of procedures that affect response variability

Response variability is sensitive to antecedent and consequent manipulations. Researchers have investigated inducement, direct production through reinforcement, and stimulus control of response variability. Recently, researchers have shown that lag reinforcement schedules reliably increase variability but may also produce higher-order stereotypy. There has been limited investigation of appropriate variability levels and alternation between repetition and variation. In a three-part study, we evaluated levels of variability across a group of children, the effects of various procedures on producing response variability and novelty, and the use of schedule-correlated stimuli for producing rapid alternation between repetition and variation. In Study 1, there was a nearly bimodal distribution of children emitting either low or high variability. In Study 2, for most children, fixed lag 4 and variable lag 4 schedules produced the highest levels of variability and novelty. In Study 3, responding was brought under control of schedule-correlated stimuli, allowing for rapid alternation between repetition and variation.

Effects of Simultaneous Script Training on Use of Varied Mand Frames by Preschoolers with Autism

Young children with autism may fail to mand using a range of frames (e.g., "I want," "May I have," "Please give me"). We examined the effects of simultaneous script training and script fading on acquisition and maintenance of varied mand frames with six preschool children with autism. For participants who did not demonstrate increased mand variability under fixed-ratio (FR) 1 conditions, we assessed the effects of post script-training extinction on response variability. Following training of up to four different mand frames, three of six participants emitted more varied mands under FR1 conditions relative to baseline. Posttraining extinction resulted in increased mand variability for two of the three remaining participants. Results are discussed in terms of considerations for both establishing and ensuring the persistence of varied verbal behavior among children with autism.

Promoting Accurate Variability of Social Skills in Children With Autism Spectrum Disorder

Restricted and repetitive behavior is a central feature of autism spectrum disorder (ASD), with such behaviors often resulting in lack of reinforcement in social contexts. The present study investigated training multiple exemplars of target behaviors and the utilization of lag schedules of reinforcement in the context of social skills training to promote appropriate and varied social behavior in children with ASD. Five participants with ASD between the ages of 7 and 9 attended a twice-weekly social skills group for 8 weeks. A multiple probe design across skills was utilized to assess intervention effects. During baseline, participants demonstrated low levels of skill accuracy and low appropriate variability in responding. During continuous reinforcement with one trained exemplar, skill accuracy increased while appropriate variability remained low. Training of three exemplars of target skills resulted in minimal improvements in appropriate variability. Introduction of a Lag 2 schedule with three trained exemplars was generally associated with increased appropriate variability. Further appropriate variability was observed during Lag 4 with three trained exemplars. Limitations and implications are discussed.

The use of a discrimination-training procedure to teach mand variability to children with autism

We investigated the effects of a script-fading and discrimination-training procedure on mand variability in preschoolers with autism. Participants were taught to vary their vocal mands in the presence of written scripts, a green placemat, and a lag schedule of reinforcement. They were also taught to engage in repetitive mands in the presence of the same written scripts and a red placemat. When the scripts were removed, all 3 participants continued to engage in varied manding in the presence of the green placemat and lag schedule, and they continued to engage in repetitive manding in the presence of the red placemat. When the lag schedule was also removed, 2 of the 3 participants continued to engage in varied responding in the presence of the green placemat and repetitive responding in the presence of the red placemat. Finally, all 3 participants demonstrated generalization and maintenance of mand variability during snack sessions with their peers.

Repetitive Behavior in Neurodevelopmental Disorders: Clinical and Translational Findings

Repetitive behavior refers to a highly heterogeneous set of responses associated with a wide range of conditions, including normative development. Treatment studies for aberrant repetitive behavior are limited although one promising approach involves conceptualizing such behavior as a generalized inflexibility or lack of variability in responding. Relatively little is known about the neurobiological mechanisms that mediate the development and expression of repetitive behavior, information critical to the design of effective pharmacotherapies, early interventions, and prevention strategies. We will review clinical findings in repetitive behavior as well as findings from animal models highlighting environmental factors and the role of cortical-basal ganglia circuitry in mediating the development and expression of these behaviors. Findings from animal models have included identification of a specific neural pathway important in mediating repetitive behavior. Moreover, pharmacological studies that support the importance of this pathway have led to the identification of novel potential therapeutic targets. Expanding the evidence base for environmental enrichment-derived interventions and focusing on generalized variability in responding will aid in addressing the broader problem of rigidity or inflexibility.