The effects of differential and lag reinforcement schedules on varied verbal responding by individuals with autism

Effect of signaled reinforcement on response variability

Three experiments examined the effect of signaling reinforcement on rats' lever pressing on contingencies that reinforced variable responding to extend the exploration of signaled reinforcement to a schedule that has previously not been examined in this respect. In Experiment 1, rats responding on a lag-8 variability schedule with signaled reinforcement displayed greater levels of variability (U values) than rats on the same schedule lacking a reinforcement signal. In Experiment 2, rats responding on a differential reinforcement of least frequent responses schedule also displayed greater operant variability with a signal for reinforcement compared with rats without a reinforcement signal. In Experiment 3, a reinforcement signal decreased the variability of a response sequence when there was no variability requirement. These results offer empirical corroboration that operant variability responds to manipulations in the same manner as do other forms of operant response and that a reinforcement signal facilitates the emission of the required operant.

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.

Using a Lag Schedule of Reinforcement to Increase Response Variability in Children With Autism Spectrum Disorders

Lag reinforcement schedules have been shown in previous research to be an effective intervention for teaching verbal and nonverbal response variability to individuals with developmental disabilities. In more recent research, variability itself has been considered a reinforceable behavior in its own right (Susa & Schlinger, The Analysis of Verbal Behavior, 18, 125-130, 2012). Lag x schedules of reinforcement can be used to teach variability by using contingencies that require responses to differ from previous responses. The present study extended Susa and Schlinger's, The Analysis of Verbal Behavior, 18, 125-130, (2012) research by using 3 social questions instead of 1 in a random rotation and included probes to test for generality. A changing-criterion design was used to evaluate the results with one 11-year-old female participant diagnosed with autism. During baseline, the participant provided little variability, with rote responses. During the Lag 1 and Lag 2 phases, appropriate variable verbal responding increased with the use of echoic prompts, visual aids, and an error correction procedure. Further, the results also showed that the participant learned to vary her responses by demonstrating the ability to emit 11 novel prompted responses and 13 spontaneous responses. In addition, the participant was able to retain the skills learned in a maintenance probe conducted 4 weeks postintervention.

Evaluation of Lag Schedules and Rules on Persistent Response Variability With Preschoolers in a Group

In the present study, experimenters evaluated the influence of lag schedules of reinforcement in combination with accurate and inaccurate (complete and incomplete) rules on the response variability of naming category items for typically developing preschoolers in a group format. Results showed that when lag schedules were introduced with 2 categories, response variability generalized to the third category. Furthermore, after participants experienced the lag schedule, variability persisted when the contingency no longer required variability. Participants continued to vary their responses unless the rule and contingency required them to repeat responses. We discuss potential clinical applications of using lag schedules in a group format and including rules during teaching, as well as directions for future research in this area.

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.

Replication and Extension of the Effects of Lag Schedules on Mand Variability and Challenging Behavior During Functional Communication Training

More is known about how to reduce challenging behavior with functional communication training (FCT) than how to mitigate its resurgence during or following a course of treatment. Research suggests reinforcing mand variability during FCT may mitigate the resurgence of challenging behavior, but validated procedures for reinforcing mand variability are limited and poorly understood. Lag schedules can reinforce variability in verbal behavior such as manding in individuals with autism, but studies have been largely limited to nonvocal mand modalities. Therefore, in the current study, we further evaluated the effects of FCT with lag schedules on vocal mand variability and challenging behavior in children with autism. The results suggest lag schedules alone or in combination with response prompt-fading strategies during FCT can increase mand variability and expand mand response classes but may fail to produce clinically significant reductions in challenging behavior.

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.

Psychoeducational Interventions for Adults With Level 3 Autism Spectrum Disorder: A 50-Year Systematic Review

There is face validity to the expectation that adults with level 3 autism spectrum disorder (ASD–3) will benefit from a range of psychoeducational interventions. This paper reviews the empirical evidence supporting the effectiveness of these interventions, many of which are currently used in clinical settings. We reviewed 56 peer-reviewed studies of psychoeducational interventions for adults with ASD–3, written in English and since 1968, that met our criteria. The reviewing team included educators, clinicians, researchers, and a biostatistician. The available literature was limited, and most, if not all, of the studies presented some significant methodological limitations. When using Cochrane’s criteria to assess seven key outcome domains—activities of daily living, aggressive/destructive behaviors, emotional functioning, language/communication skills, self-injurious behaviors, stereotypy/mannerisms, and vocational skills—we found only moderately reliable evidence to support the effectiveness of interventions designed to improve emotional functioning in adults with ASD–3. The reliability of evidence relevant to the six other outcome domains was rated as low or very low. Based on this review, we suggest directions for future study of interventions for adults with ASD–3, including topics, subpopulations, and approaches that should be explored. We also propose some crucial changes in how future studies regarding this population should be designed, analyzed, and documented, while balancing clinical considerations with scientific/educational utility.

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.

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.

An evaluation of the additive effects of lag schedules of reinforcement

Lag schedules of reinforcement represent an increasingly researched strategy for addressing restricted and repetitive social communication of individuals with autism spectrum disorder (ASD). Although the body of literature suggests that lag schedules of reinforcement are generally effective for this purpose, studies have varied in their utilization of verbal rules describing the contingency. Furthermore, research has yet to evaluate generalized effects of lag schedules of reinforcement to social communication with peers. This study evaluated the implementation of a social skills curriculum, modified to incorporate lag schedules of reinforcement, on novel responding of participants with ASD. Participants attended training twice per week, with probes of novel responding collected with both researchers and non-participating peers. Results indicate that social skills training that incorporated lag schedules of reinforcement generally resulted in larger increases in novel responding than social skills training alone. Furthermore, effects of training generalized to novel responding to non-participant peers.

Generalization of learned variability across multiple dimensions in humans

This study examined whether trained variability would generalize across dimensions of the target response. Two experiments used a computerized rectangle drawing task that required participants to click and drag a mouse cursor to create rectangles on a computer screen. In Experiment 1, one group received points when successive rectangles varied in their size, shape and location (VAR), another group were yoked to the VAR group and received points that were allocated to them using a yoking procedure (YOKE), regardless of the variability in the size, shape or location of the rectangle drawn. Variability was higher for a dimension when variability on that dimension was directly reinforced. In Experiment 2, three groups of participants received points when rectangles varied on two dimensions; each group differed in the two dimensions that required variation. Variability was again higher for the reinforced dimensions for two of the three groups. Comparison with the YOKE group showed that the variability on those dimensions where variability was not directly reinforced was affected by reinforcement for variability on the other dimensions. Specifically, the variability in Shape and Location was significantly higher when these two dimensions occurred with other dimensions where variability was reinforced (as in Experiment 2) compared to when they were not required to vary (as in the YOKE group). This suggests that, for these two groups, the reinforced variability on the other two dimensions generalized to the third dimension. Implications of this finding to our understanding of factors that promote behavioral variability are discussed.

Promoting Conditional Use of Communication Skills for Learners With Complex Communication Needs: A Tutorial

PURPOSE

Conditional use of communication skills refers to the ability of a learner to appropriately generalize and discriminate when, where, and how to communicate based on constant variation and shifts in environmental cues.

METHOD

We describe discrimination and generalization challenges encountered by learners with complex communication needs and ways in which these challenges are fostered through traditional communication intervention programming. We address arrangements in instruction that maximize the probability of learners acquiring the conditional use of new vocabulary and the modest instructional technology implemented when planning for generalization.

RESULTS

We propose establishing well-discriminated and generalized use of new vocabulary items through the application of a general case instruction framework to communication intervention programming.

CONCLUSION

We provide intervention methodology, including intervention steps for general case instruction, a plethora of functional examples, and graphic displays to assess and intervene to promote conditional use of communication skills for learners with complex communication needs.

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.

Lag Schedules and Functional Communication Training: Persistence of Mands and Relapse of Problem Behavior

We evaluated the effects of lag schedules of reinforcement and functional communication training (FCT) on mand variability and problem behavior in two children with autism spectrum disorder. Specifically, we implemented FCT with increasing lag schedules and compared its effects on problem behavior with baseline conditions. The results showed that both participants exhibited low rates of problem behavior during treatment relative to baseline during and following schedule thinning (up to a Lag 5 schedule arrangement). Variable and total mands remained high during schedule thinning. With one participant, variable manding persisted when the value of the lag schedule was reduced to zero. The current results are discussed in terms of implications for training multiple mand topographies during FCT for the potential prevention and/or mitigation of clinical relapse during challenges to treatment.

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.

Enhancing appropriate and variable responding in young children with autism spectrum disorder

OBJECTIVE

The present study utilized lag schedules of reinforcement, in conjunction with training multiple exemplars and provision of prompts, to promote appropriate variability of social skills.

METHODS

Participants included in three children between the ages of 5 and 7 with ASD. Participants attended a social skills training program twice per week for eight weeks. A multiple probe design across target social skills was used to assess the effects of intervention.

RESULTS

Findings indicate that training multiple exemplars alone did not appreciably increase appropriate and variable responding, whereas the addition of lag schedules of reinforcement and prompting to training multiple exemplars resulted in appropriate and variable responding that exceeded baseline levels.

CONCLUSION

Use of lag schedule of reinforcement in conjunction with prompts was more effective than multiple exemplar training in isolation for increasing appropriate variability of social skills.

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.

Application of a lag contingency to reduce perseveration on circumscribed interests

OBJECTIVE

To evaluate the effects of a lag reinforcement contingency on the conversation topics of children diagnosed with autism who perseverated on circumscribed interests (CIs).

METHOD

Single-case design study with two participants, age 11 and 12 years. A functional analysis employed an alternating-treatments design to assess effects of contingent attention on conversational behavior. A multiple-baseline with an embedded reversal design was employed in a subsequent lag contingency analysis, in which the conversation partner provided attention at the end of each 10 s interval if the content of the participant's conversation met the requirement of a Lag 0, Lag 1, or Lag 2 contingency.

RESULTS

The participants' conversational behavior was sensitive to a conversation-partner's attention as a consequence. Lag contingencies successfully altered the prevalence of CI-related and-unrelated talk.

CONCLUSION

Lag contingencies can shift conversation content away from CIs, but further research is needed to identify appropriate treatment goals with respect to variability and content.

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.

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.

Teaching complex verbal operants to children with autism and establishing generalization using the peak curriculum

The present study evaluated the feasibility of the PEAK Relational Training System's Generalization Module (Dixon, 2014b) to teach and establish generalization of autoclitic mands, distorted tacts, and creative path finding in three children diagnosed with autism spectrum disorder. Using a multiple-baseline design across behaviors, each participant was provided with differential reinforcement and a least-to-most prompting hierarchy for correct responses to a subset of stimuli, and responses to other similar stimulus sets were probed for emergent generalization. Following training, each participant successfully acquired the directly trained behaviors and demonstrated generalization to the nonreinforced test exemplars. These data support the utility of Skinner's (1957) analysis to teach complex forms of verbal operants, and suggest that a manualized curriculum such as PEAK may have utility for promoting skill development and generalization for front line staff and caregivers of children with autism.

Using Instructive Feedback to Increase Response Variability During Intraverbal Training for Children with Autism Spectrum Disorder

We evaluated the effects of instructive feedback on the variability of intraverbal responses for two children with autism spectrum disorder. Specifically, we used an adapted alternating treatments design to compare participants' novel responses and response combinations during an intraverbal category program across conditions with and without instructive feedback. During instructive feedback, secondary targets were presented during the consequence event of the learning trial and consisted of a therapist's model of response variability. The results showed that participants engaged in more novel response combinations during instructive feedback conditions. We discussed the clinical implications of these results as well as areas for future research.

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.

Meta-analysis of social skills interventions of single-case research for individuals with autism spectrum disorders: results from three-level HLM

This meta-analysis used hierarchical linear modeling to examine 115 single-case studies with 343 participants that examined the effectiveness of social skills interventions for individuals with autism spectrum disorder (ASD). The average effect size of the included studies was 1.40 (SD = 0.43, 95% CL = 1.32-1.48, N = 115). In the further, several common predictors including intervention length, age and gender of the participants, and study quality indicators (provision of sufficient, in-depth, and replicable information of participants, settings/materials, independent variables, and dependent variables) were not found to mediate the intervention effectiveness. Only research design that the study employed was found to impact the intervention effectiveness; the studies using multiple baseline or reversal design had larger effect sizes than studies using other designs. Implications of the results and limitations of this study are discussed.

Using a lag reinforcement schedule to increase phonemic variability in children with autism spectrum disorders

Shaping functional vocal language is difficult when an individual has not yet acquired an echoic repertoire and does not emit sufficient phonemes (i.e., speech sounds) for shaping. Few studies have evaluated interventions to increase the frequency and breadth of phonemes. The current study extended Esch, Esch, and Love (2009) by evaluating the effects of a Lag 1 reinforcement schedule on vocal variability and limiting the definition of variability to responses that incorporated a novel phoneme. For 2 of the 3 participants, the cumulative number of novel phonemes, the percentage of trials with variability, and the number of different phonemes emitted per session increased during the Lag 1 intervention phase.

Reinforced variability enhances object exploration in shy and bold rats

In an open-field test, the Long-Evans (LE) strain of rats was identified as "bold" and the PVG strain as "shy." Some members of each strain then experienced 14 sessions of a common enrichment procedure, namely exposure to a series of novel objects (Exposed). Others in each strain were explicitly reinforced with food pellets for variable interactions with the same objects (Reinforced). Both experience and strain influenced object interactions. In particular, Reinforced rats interacted more variably with the objects - contacting, probing, pushing and so forth - than did the Exposed; and LEs interacted more variably than PVGs. Foraging proficiency in the same rats was then studied in a transfer-of-training test. Food pellets were hidden among never-before experienced objects and the rats were permitted to explore freely. Reinforced rats discovered and consumed more pellets than Exposed; and LEs discovered and consumed more than PVGs. Thus a bold genetic strain and reinforcement of variability independently contributed to successful foraging behavior.

Using a lag schedule to increase variability of verbal responding in an individual with autism

Research has shown that reinforcing novel behaviors can increase the number of different ways that an individual behaves (Goetz & Baer, 1973; Pryor, Haag, & O'Reilly, 1969). However, it was not until more recently that researchers began to consider variability to be a reinforceable operant in and of itself (Neuringer, 2002). More specifically, Neuringer suggested that variability can be taught using a Lag x schedule of reinforcement, in which x refers to the number of previous responses from which the current response must differ in order for reinforcement to occur (Page & Neuringer, 1985). The purpose of the present study was to extend one of the first studies of a Lag x schedule on verbal responses with human subjects (Lee, McComas, & Jawor, 2002), by increasing the lag criteria while attempting to address some of methodological limitations of the study. The participant was a 7-year-old male with autism. A changing criterion design was used and results showed that 3 novel responses were acquired and varied according to the lag schedule of reinforcement.

Increased variability in tacting under a lag 3 schedule of reinforcement

Research has shown that variability may be an operant dimension of behavior. One method of reinforcing response variability is to use a lag schedule of reinforcement (Page & Neuringer, 1985). Several studies have shown that a Lag 1 schedule is effective in increasing variable responding with human participants (e.g., Esch, Esch, & Love, 2009; Lee, McComas, & Jawor, 2002). In these arrangements, however, the return to baseline responding during reversal phases suggests that the resulting behavior change may not be maintained following intervention. The purpose of the present study was to investigate the effects of a Lag 3 schedule on increasing and maintaining variability of tacts in 2 children diagnosed with developmental disabilities. Results demonstrated increased variability in tacting for both participants and maintenance in variable responding after a 3-week follow-up.