Interpreting treatment effect size from single case experimental design data: a preliminary analysis of differential effects of treatments designed to increase or decrease behaviour.

BACKGROUND: Estimates of treatment effect size from single case experimental design (SCED) data may be impacted by the direction for treatment effects (i.e. ascending or descending slope for the dependent variable). Estimating effect sizes for treatments designed to decrease behaviour are potentially more restricted because the intended direction for treatment is zero (i.e. an absolute basal). Conversely, effect sizes for interventions that increase behaviour are less restricted due to a relatively unconstrained ceiling from a pure measurement standpoint (i.e. no absolute ceiling). That is, treatments that increase behaviour have a broader range of possible effect size values as the ceiling is only limited by demand characteristics and the learners' skills and motivation to exhibit the behaviour. METHOD: The current study represents a preliminary analysis of the mean and range of SCED effect sizes for treatments designed to either increase or decrease target behaviour. A within-case Cohen's d measure that was developed for SCED data was used to estimate treatment effect sizes. RESULTS: Results indicated that the mean and range of effect size values for treatments that increased behaviour were significantly greater compared with treatments that decreased behaviour. CONCLUSIONS: Results are discussed in terms of developing standards, or best practices, specific to interpreting effect size values and meeting quality control requirements for inclusion of the data set in future SCED meta-analytic studies estimating treatment effect size. Specifically, preliminary results suggest that benchmarks for low, medium and high SCED effect size values need to be developed separately for treatments that increase or decrease levels of the dependent variable.

Predictors of self-injurious behaviour exhibited by individuals with autism spectrum disorder.

BACKGROUND: Presence of an autism spectrum disorder is a risk factor for development of self-injurious behaviour (SIB) exhibited by individuals with developmental disorders. The most salient SIB risk factors historically studied within developmental disorders are level of intellectual disability, communication deficits and presence of specific genetic disorders. Recent SIB research has expanded the search for risk factors to include less commonly studied variables for people with developmental disorders: negative affect, hyperactivity and impulsivity. METHOD: A heterogeneous sample of 617 individuals with autism spectrum disorder diagnoses was derived from the National Database of Autism Research. Latent constructs were estimated from items of the community version of the Aberrant Behaviour Checklist. Structural equation modelling was used to assess whether impulsivity, hyperactivity, negative affect, severity of stereotypy, intellectual functioning or severity of autism symptoms predicted severity of SIB. RESULTS: Impulsivity (ß = 0.46), followed by intellectual functioning (ß = -0.39), and stereotypy (ß = 0.23) were the variables most highly predictive of increased SIB; impulsivity and stereotypy remained significant predictors of SIB after severity of autism symptoms and intelligence quotient (IQ) were controlled for. CONCLUSIONS: High levels of impulsivity and stereotypy were significant predictors of SIB in a large and diverse sample of people with confirmed autism diagnoses. Future research is needed on the effects of reducing impulsivity and stereotypy on the outcomes of treatment, early intervention and attempts to prevent the development of SIB.

Early intervention and prevention of self-injurious behaviour exhibited by young children with developmental disabilities.

The ontogeny of self-injurious behaviour exhibited by young children with developmental delays or disabilities is due to a complex interaction between neurobiological and environmental variables. In this manuscript, the literature on emerging self-injury in the developmental disability population is reviewed with a focus on an operant conceptual model of how topographies of self-injurious behaviour can change structurally and become sensitive to various environmental consequences. Results of previous studies are reviewed in terms of extending our research focus from a reactive model of assessment and treatment of well-established cases of self-injury to an early intervention and prevention model.

Stimulus characteristics within directives: effects on accuracy of task completion.

Three experiments were conducted in an outpatient setting with young children who had been referred for treatment of noncompliant behavior and who had coexisting receptive language or receptive vocabulary difficulties. Experiment 1 studied differential responding of the participants to a brief hierarchical directive analysis (least-to-most complex stimulus prompts) to identify directives that functioned as discriminative stimuli for accurate responding. Experiment 1 identified distinct patterns of accurate responding relative to manipulation of directive stimulus characteristics. Experiment 2 demonstrated that directives identified as effective or ineffective in obtaining stimulus control of accurate responding during Experiment 1 continued to control accurate responding across play activities and academic tasks. Experiment 3 probed effects of the interaction between the type of directive (effective vs. ineffective) and the reinforcement contingency (differential reinforcement for attempts vs. differential reinforcement for accurate responses) on accurate task completion and disruptive behavior. Results suggested that behavioral escalation from inaccurate responding to disruptive behavior occurred only when ineffective directives were combined with differential reinforcement for accurate task completion. The overall results are discussed in terms of developing a methodology for identifying stimulus characteristics of directives that affect accurate responding.

Response efficiency during functional communication training: effects of effort on response allocation.

An analogue functional analysis revealed that the problem behavior of a young child with developmental delays was maintained by positive reinforcement. A concurrent-schedule procedure was then used to vary the amount of effort required to emit mands. Results suggested that response effort can be an important variable when developing effective functional communication training programs.

Functional analysis and treatment of breath holding maintained by nonsocial reinforcement.

A functional analysis showed that breath holding exhibited by a 16-year-old boy with mental retardation occurred independent of social consequences. Assessment results of the existing treatment procedure-a verbal reprimand-were used to design a treatment package that reduced the behavior to low levels across 7 months.

Evaluating the effects of functional communication training in the presence and absence of establishing operations.

We conducted functional analyses of aberrant behavior with 4 children with developmental disabilities. We then implemented functional communication training (FCT) by using different mands across two contexts, one in which the establishing operation (EO) that was relevant to the function of aberrant behavior was present and one in which the EO that was relevant to the function of aberrant behavior was absent. The mand used in the EO-present context served the same function as aberrant behavior, and the mand used in the EO-absent context served a different function than the one identified via the functional analysis. In addition, a free-play (control) condition was conducted for all children. Increases in relevant manding were observed in the EO-present context for 3 of the 4 participants. Decreases in aberrant behavior were achieved by the end of the treatment analysis for all 4 participants. Irrelevant mands were rarely observed in the EO-absent context for 3 of the 4 participants. Evaluating the effectiveness of FCT across different contexts allowed a further analysis of manding when the establishing operations were present or absent. The contributions of this study to the understanding of functional equivalence are also discussed.

Further analysis of problem behavior in response class hierarchies.

A functional analysis identified the reinforcers for 3 participants' problem behavior, but only relatively mild problem behaviors (e.g., screaming, disruption) were observed when all topographies produced tested consequences. We then conducted an extinction analysis in which specific topographies produced a reinforcer while all other topographies were on extinction. The extinction analysis confirmed that the same reinforcer identified in the initial functional analysis maintained more severe topographies of problem behavior (e.g., aggression). In addition, results of the extinction analysis indicated that 2 of the participants displayed patterns of responding consistent with a response class hierarchy hypothesis, in which less severe problem behavior frequently occurred prior to more severe topographies. The 3rd participant displayed a response pattern indicative of differential reinforcement effects.

On the effects of "quality" of attention in the functional analysis of destructive behavior.

Two young children with mental retardation displayed inconclusive patterns of destructive behavior when a functional analysis was conducted using the procedures described by Iwata et al. (1982/1994). A second functional analysis incorporated modifications to the social attention condition that were based on interview data from care providers and descriptive observations. Results of the modified social attention condition indicated that a specific "quality" of attention was needed to identify the maintaining contingency for destructive behavior within an experimental analysis. Results are discussed in terms of considerations for further assessment when traditional analog functional analysis conditions are ineffective in isolating maintaining contingencies for destructive behavior.

Functional analysis and extinction of different behavior problems exhibited by the same individual.

Specific extinction procedures were matched to the function of two target behaviors displayed by the same individual, with results indicating that the matched extinction procedure suppressed the behavior for which it was designed. One of the target behaviors was exposed to an irrelevant extinction procedure, which produced no beneficial effects. These results support previous research indicating the need to match extinction procedures to the function of problem behavior.

Using pretreatment and posttreatment assessments to enhance and evaluate existing treatment packages.

Pretreatment assessment data were used to enhance an existing treatment package to reduce aggression and to increase positive social interactions between a young boy and his peers. Based on the results of pretreatment assessments, additional reinforcement (differential reinforcement of alternative behavior with adult attention) and punishment (performing a nonpreferred task during time-out) components were added to an existing nonresetting differential reinforcement of other behavior (access to peers unless aggression occurred) plus time-out procedure. A posttreatment component analysis of the additional treatment components indicated that the reinforcement component facilitated positive social interactions and the punishment component suppressed aggression towards peers.