Peer-mediated discrete trial training within a school setting

Research in Autism Spectrum Disorders 9 (2015) 53–67

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Peer-mediated discrete trial training within a school setting Keith C. Radley *, Evan H. Dart, Christopher M. Furlow, Emily J. Ness Department of Psychology, University of Southern Mississippi, Hattiesburg, MS, United States

A R T I C L E I N F O

A B S T R A C T

Article history: Received 16 July 2014 Received in revised form 30 September 2014 Accepted 3 October 2014

The present study evaluated the feasibility and effects of a peer-mediated, school-based, discrete trial training (DTT) protocol for students with autism spectrum disorder (ASD). Six typically developing elementary-age peers were trained to implement a basic DTT protocol. A multiple baseline across student interventionists design was utilized to evaluate the integrity with which trained peers implemented the DTT protocol and the efficacy of the student interventionists in training target academic behaviors. Results indicate that student interventionists acquired skills to implement the DTT protocol with high levels of integrity. Additionally, it was observed that participation in peer-mediated DTT resulted in mastery of target academic skills by participants with ASD. Measures of acceptability indicated high levels of student interventionist satisfaction with intervention procedures. ß 2014 Elsevier Ltd. All rights reserved.

Keywords: Discrete trial training Peer-mediated intervention Academic intervention

1. Introduction According to the Centers for Disease Control Autism and Developmental Disabilities Monitoring Network (2014), it is estimated 1 in 68 children have been identified with an autism spectrum disorder (ASD). Further, the U.S. Department of Education reports 7% of children between the ages of 6 and 21 receiving special education services in public schools under the Individuals with Disabilities Education Act (IDEA) fall into the autism category, and only 56% of children with an autism spectrum disorder finish high school (Wagner, Newman, Cameto, Levine, & Garza, 2006). Given poor academic outcomes of children with ASD (e.g., Howlin, Mawhood, & Rutter, 2000), it is necessary to identify interventions that may promote acquisition of academic skills. Due to the amount of research that has been completed since the 1960s, applied behavior analysis (ABA) has been recognized by the Surgeon General of the United States as representative of best practice for individuals with ASD (Department of Health, 1999). Individuals with ASD often require specialized behaviorally based interventions to address deficits in communication, social interaction, and academics (Matson & LoVullo, 2008; National Research Council, 2001). A common, evidence based instructional strategy which can be individualized to address each of these deficits is discrete trial training (DTT). Grounded in the experimental analysis of behavior, DTT is a specific type of teacher-directed instruction that utilizes simple instructional cues, prompting, reinforcement, and data-based decision making to shape behavior and improve children’s learning (Smith, 2001). The primary technique used throughout the DTT method of instruction, regardless of

* Corresponding author at: Department of Psychology, University of Southern Mississippi, 118 College Drive # 5025, Hattiesburg, MS 39406-001, United States. Tel.: +1 601 266 6748. E-mail address: [email protected] (K.C. Radley). http://dx.doi.org/10.1016/j.rasd.2014.10.001 1750-9467/ß 2014 Elsevier Ltd. All rights reserved.

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target skill, consists of four parts: (a) the trainer’s presentation of a discriminative stimulus to which a child responds, (b) the child’s response, (c) the consequence, and (d) a short pause prior to the next command (Anderson, Taras, & O’Malley-Cannon, 1996; Malott & Trojan-Suarez, 2004). DTT has been shown to be an efficient approach for teaching children with ASD new and difficult skills in important areas including, but not limited to, language, social, and academic skills (Leaf & McEachin, 1999; Lovaas & Smith, 2003; Smith, 2001; Sturmey & Fitzer, 2007). As a result, DTT has been utilized to significantly improve the developmental and educational outcomes of children with autism and developmental delay (Lovaas, 1987a, 2003; McEachin, Smith, & Lovaas, 1993; Smith, 1999); therefore, this approach has proven particularly effective in helping young children with autism acquire a wide range of new skills (e.g., Coe, Matson, Fee, Manikam, & Lanarello, 2009; Gutierrez et al., 2009; Sarokoff & Sturney, 2008; Young, Krantz, McClannahan, & Poulson, 1994). Due to its many demonstrated strengths and apparent effectiveness, DTT has been classified as an evidence-based practice by the National Autism Center (2010) and the National Research Council (2001); and many parents of children with autism have increasingly requested that their children be provided publicly funded DTT-based educational programming (Choutka, Doloughty, & Zirkel, 2004). This method of instruction has been successfully implemented by teachers, parents, paraprofessionals, graduate and undergraduate students (Crockett, Fleming, Doepke, & Stevens, 2007; Devlin & Harber, 2004; Dib & Sturmey, 2007; Downs, Downs, & Rau, 2008; Fazzio, Martin, Arnal, & Yu, 2009; Sarokoff & Sturmey, 2008; Severtson & Carr, 2012). Despite this evidence, several challenges may prohibit utilization of DTT in school settings. The one-on-one format frequently utilized in schools removes children with ASD from settings in which they may interact with peers and limits their inclusion in the least restrictive environments (Skokut, Robinson, Openden, & Jimerson, 2008). Although DTT may be used to instruct groups of children (e.g., Leaf et al., 2013; Ledford, Gast, Luscre, & Ayres, 2008), group instruction is likely to reduce opportunities to respond, and such procedures may inefficiently target individual behaviors (e.g., Lovaas, 1987a,b; Skokut et al., 2008) – particularly when children within a classroom demonstrate different instructional objectives and goals. Possibly the most salient barrier to implementation of DTT in the school setting is that it is very time-consuming for teachers to implement, making DTT difficult to implement for teachers who may be responsible for multiple children with ASD at one time. As such, Steege, Mace, Perry, and Longenecker (2007) cautioned against using a school-based DTT program for students with ASD as there may not be enough time available for the teacher to implement the intervention successfully. In order to increase the feasibility of DTT in school settings, alternative strategies of implementation should be considered. One strategy for promoting the feasibility of school-based DTT is to increase the number of trained interventionists. Previous research has found strategies such as video modeling and didactic instruction to be effective in prompting accurate use of a DTT protocol (e.g., Catania, Almeida, Liu-Constant, & DiGennaro-Reed, 2009; Hay-Hansson & Eldevik, 2013). Instruction in facilitation of DTT has been found to be particularly effective when training incorporates instruction, opportunities to practice DTT, and feedback (Catania et al., 2009). Increasing the number of trained interventionists allows for school-based DTT to target diverse academic objectives of multiple students simultaneously, addressing a substantial limitation of school-based DTT (e.g., Skokut et al., 2008). In addition to training additional staff to implement DTT, others have suggested that school feasibility be increased by utilizing students as interventionists to supplement teacher-facilitated intervention (Fazzio et al., 2009) – particularly as peer-mediated DTT may allow children with ASD to develop important skills through both contact with typically developing peers and individualized instruction. Peer-mediated intervention is a treatment approach in which students are trained to act as the intervention agents, implementing instructional programs, behavioral interventions, and facilitating social interactions (Garrison-Harrell, Kamps, & Kravitz, 1997; Laushey & Heflin, 2000a). Peer tutoring, a type of peer-mediated intervention, describes the process of peers providing one-one one individualized instruction (Utley, Mortweet, & Greenwood, 1997). There are many benefits to utilizing peer-mediated interventions, particularly peer tutoring, in schools. For example, the abundance of peers within the school means the availability of many intervention agents. Training peers to implement interventions may lead to additional opportunities for the generalization of skills across individuals and, since the child with ASD may have an opportunity to practice skills with multiple people (Carr & Darcy, 1990; Stokes & Baer, 1977; Stokes, Doud, Rowbury, & Baer, 1978). This may also reduce demands on teachers and other professionals while also increasing the amount of intervention access for the individual with ASD. An additional benefit is that the direct interaction between a student with ASD and typically developing students may also foster inclusion in school settings. This way, students with ASD have the opportunity to create relationships with peers without disabilities leading to an increase in the number of available social partners. In otherwords, as the individual with ASD acquires new skills, they may also gain greater access to the educational environment that may be augmented by facilitating relationships with the other people in that environment (Chan et al., 2009). Peer-mediated interventions have received substantial support as a viable strategy for service delivery in schools. For example, some of the interventions that have previously used students as intervention agents have addressed a variety of issues such as improving reading fluency (Dufrene et al., 2010), teaching social studies (Scruggs, Mastropieri, & Marshak, 2012), improving social skills and prosocial behaviors (Harjusola-Webb, Hubbell, & Bedesem, 2012; Hughes et al., 2013), and using alternative and augmentative communication (Trembath, Balandin, Togher, & Stancliffe, 2009). These results have been achieved within both special education and general education for students in elementary school, middle school, and high school (Hughes et al., 2013; Lindauer & Petrie, 1997; Utley et al., 1997). The literature supporting the effectiveness of peer-mediated interventions specifically for students with ASD is also robust. Although

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much of the literature has focused on peer-mediated social skills interventions (e.g., Laushey & Heflin, 2000b; Petursdottir, McComas, McMaster, & Horner, 2007), a meta-analysis conducted by Zhang and Wheeler (2011) suggests that these interventions are highly effect for teaching social initiation and responding to students with ASD (ES = 1.46). Research also suggests that peer interventionists also benefit from participation in peer-mediated interventions. Kamps, Barbetta, Leonard, and Delquadri (1994) found peer tutoring to result in improvements in academic performance of tutors. Peer-mediated interventions have also been found to result in improved self-competence and attitudes toward academic subjects, as well as produce increased interaction between student interventionists and tutees (Franca, Kerr, Reitz, & Lambert, 1990). Additionally, increased interaction of typically developing children with children with disabilities may result in greater acceptance of individuals with disabilities (Favazza & Odom, 1996). Although peer-mediated interventions and the procedures of DTT are separately well established in the literature, only a single study has examined the effectiveness of a peer-mediated DTT intervention to promote skill acquisition in students with ASD. Schreibman, O’Neill, and Koegel (1983) trained typically developing siblings of students with ASD to implement a discrete trial intervention protocol with them in order to teach skills such as receptive identification, stimulus discrimination, and expressive and receptive labeling. The results demonstrated that training in DTT produced high implementation integrity and application of the DTT procedures produced considerable skill acquisition above baseline levels. The limited research on peer-mediated DTT supports the use of this strategy in the education of children with ASD; however, no studies have evaluated the applicability of such procedures within school settings. Given the need for effective academic interventions for children with ASD, coupled with the challenges of implementation of DTT procedures within school settings (e.g., Eikeseth, 2010; Skokut et al., 2008; Steege et al., 2007), strategies to promote learning within school settings must be investigated. Therefore, the purpose of this study was to answer the following questions: 1. Can middle school students who serve as student interventionists implement discrete trial training procedures with sufficient integrity? 2. What is the effect of middle school students as student interventionists using discrete trial training methods on the correct/independent responding of participants with ASD? 3. Is discrete trial training considered an acceptable intervention by middle school student interventionists? 2. Methods 2.1. Participants and setting Two participants with ASD were recruited for inclusion in the current study. Both participants had clinical diagnoses of ASD from a licensed psychologist and had special education classifications of Autism. Participants were placed within a self-contained special education classroom for students with developmental disabilities within a public elementary school. Participants were nominated for inclusion by teachers for requiring additional teaching opportunities in order to meet Individual Education Plan (IEP) objectives. Jimmy (pseudonyms used throughout), a 7-year-old male, had a diagnosis of autism from a licensed psychologist and a special education ruling of Developmental Disability in the areas of cognitive and communication skills. On the Battelle Developmental Inventory, Second Edition (BDI-2; Newborg, 2005) Cognitive Domain, Jimmy received a standard score of 51, a score below the 0.1 percentile. Jimmy engaged in frequent problem behaviors (e.g., off-task, out of seat behavior, yelling) and stereotypy (e.g., spinning, arm waving). Teachers reported that these disruptive behaviors coupled with cognitive delays often hindered his teachers’ ability to complete instructional tasks with him, slowing his skill acquisition and academic progress. He had below average motor skills and adaptive skills. He had a limited vocal repertoire, consisting of grunting and yelling, and communicated primarily through gestures. Jimmy received speech and language services and had previous experience with functional communication training (FCT), demonstrating occasional use of two picture cards within the classroom. Jimmy was not engaged in the FCT intervention at the time of the current study. Ritchie, a 6-year-old male, had a special education ruling of Autism. On the BDI-2 Cognitive Domain, Ritchie received a standard score of 57 o, a score at the 0.1 percentile. He displayed poor reading and math skills and below average adaptive and motor skills. In terms of verbal behavior, Ritchie demonstrated one-word imitative abilities, with the primary means of communication being gestural. Ritchie was not receiving any additional services at the time of the current study beyond that offered within the self-contained classroom. Six typically developing peers were also included in the study as student interventionists. Typically developing peers were fifth grade students ranging in age from 10 to 11 years old who attended the same public school as the participants with ASD. Fifth grade teachers were asked to nominate high-achieving, responsible, trustworthy students who would make good student interventionists. Peers nominated for inclusion included four females, Angelina, Ginny, Katie, and Alicia, and two males, Jack, and Andrew. Prior to inclusion in the study, parental consent and student interventionist assent was collected. Peer-mediated DTT was conducted within the self-contained classroom. The training area measured 8 m  5 m. A table and two chairs were present in the training area to allow for conducting DTT sessions. Additional materials present in the training environment included preferred reinforcers as identified through a multiple stimuli without replacement preference assessment (Roane, Vollmer, Ringdahl, & Marcus, 1998).

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2.2. Materials Materials utilized in the current study include a training script (Appendix A), utilized during sessions in which student interventionists were trained by researchers to implement DTT, intervention integrity checklists, and participant responding scoring sheets. Additional materials utilized in the current study include chips, Cheez-It1 crackers, Cap’n Crunch1 cereal, Marvel1 Iron Man Spin Globe, Flashing Ball, alphabet blocks, and a computer, items identified for use in the current study during preference assessments with participants with ASD. 2.3. Measures 2.3.1. Intervention integrity The primary dependent variable in the current study was integrity of implementation of DTT. This was operationally defined as the successful demonstration of DTT components by peers during teaching sessions. To assess intervention integrity, researchers observed peer-mediated DTT sessions using an intervention integrity checklist (Table 1). At the beginning of each DTT session, researchers scored the student interventionists’ performance on five preparatory steps: placing the bin of reinforcers out of the participant’s reach; placing task-specific materials in front of the participant; stopping the participant from playing with preferred items; getting the participant’s attention by patting their hands in their lap; and saying ‘‘Get Ready.’’ Following the observation of these preparatory steps, researchers scored the student interventionists’ performance on each of the six steps included in the DTT protocol during each trial. The steps included: presentation of a clear discriminative stimulus (SD); providing an appropriate prompt (e.g., guiding or modeling a response); delivering a consequence dependent upon participant response (e.g., social praise and access to tangible reinforcer); appropriate fading of prompt (e.g., hand over hand to gestural, gestural to independent); and appropriate correction of any errors if prompt fading was unsuccessful. A total of 10 trials were presented during each DTT session. The percentage of correctly implemented DTT steps by student interventionists was calculated by dividing the number of correctly demonstrated steps by the total number of possible steps (i.e., 65) and multiplying by 100. 2.3.2. Correct/independent responding of academic skills Correct/independent of target academic skills by participants with ASD, operationally defined as correct touching of an object following the presentation of a discriminative stimulus, was collected as a secondary dependent variable. Researchers observed responding of participants with ASD during trials, with each response being scored as correct/ independent, prompted via physical or gestural prompt, or incorrect. Participant responding was recorded during each of the 10 trials presented. Correct/independent responding was calculated by dividing the number of trials scored correct/independent by the total number of trials administered and multiplying by 100. Additionally, percentage of trials scored as prompted was also calculated. 2.3.3. Social validity Social validity of training and intervention procedures was assessed through administration of a modified version of the Behavior Intervention Rating Scale (BIRS; Elliott & Von Brock-Treuting, 1991) to student interventionists. The questionnaire contained 24 items endorsed on a 6-point Likert scale ranging from ‘strongly disagree’ (1) to ‘strongly agree’ (6). Psychometric evaluations indicate three factors, acceptability, effectiveness, and time of effectiveness. Factors have been found to have high construct validity and reliability, with alpha coefficients of .97, .92, and .87, respectively. 2.4. Experimental conditions 2.4.1. Design A concurrent multiple baseline across participants design (Cooper, Heron, & Heward, 2007) was utilized to assess intervention integrity and participant responding. Utilization of multiple baseline designs with staggered implementation Table 1 Intervention integrity checklist. Intervention component

Component score

1. Placed bin of toys/snacks out of the student’s reach 2. Placed task specific teaching materials in front of the student 3. Stopped the student from playing with preferred items 4. Got the student’s attention by patting your hands in your lap 5. Said: ‘‘Get Ready!’’ 6. Presented correct instruction. (i.e., correct SD) 7. Provided appropriate prompt 8. Provided appropriate reinforcement 9. Accurately recorded data following each trial 10. Attempted to fade prompts appropriately 11. Attempted to correct any errors

Y Y Y Y Y 1 1 1 1 1 1

N N N N N 2 2 2 2 2 2

3 3 3 3 3 3

4 4 4 4 4 4

5 5 5 5 5 5

6 6 6 6 6 6

7 7 7 7 7 7

8 8 8 8 8 8

9 9 9 9 9 9

10 10 10 10 10 10

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of intervention across three series allows for documentation of a functional relation (Horner, Carr, McGee, Odom, & Wolery, 2005). The current study consisted of two phases: baseline and intervention. 2.4.2. Baseline Prior to collection of baseline data, researchers consulted with teachers to identify skills included as educational objectives on participants’ IEPs. Three IEP objectives were selected as target skills for each participant. For Jimmy, object-toobject identical matching of a marker, receptive identification of the number ‘‘two,’’ and picture-to-picture identical matching of a square were selected. For Ritchie, receptive identification of a circle, object-to-object identical matching of a cube, and picture-to-picture identical matching of a circle were selected. Each of the target stimuli was presented with two distracter stimuli in an array of three. Following consultation with teachers to identify skills to be taught, three student interventionists were randomly assigned to each participant with ASD by drawing names out of a bag. Angelina, Ginny, and Jack were assigned to Jimmy, whereas Andrew, Katie, and Alicia were assigned to Ritchie. Once assigned to a participant with ASD, each student interventionist was randomly assigned a target skill to teach to the participant with ASD. During baseline, both Jimmy and Ritchie were provided with peer-mediated DTT concurrently, in the same training area. In this way, it was possible for one adult to supervise both sessions simultaneously, effectively doubling the time efficiency of the intervention over traditional adult-mediated DTT. Each session lasted approximately 30 min. The student interventionists rotated in and out of the training area throughout the 30-min session such that each student interventionist was present for 10 min of the entire session to teacher his or her assigned skill. Only two student interventionists were ever present at any given time, one providing DTT to Jimmy and the other providing DTT to Ritchie. During baseline sessions, student interventionists were instructed to teach their assigned participant the target skill, provided with a data collection sheet, and told to record how well the participant responded during 10 trials. No information regarding instruction or accurate scoring of responding was provided. All required stimuli and reinforcers were present in the training setting. Student interventionists were then introduced to the training setting with a participant and the researcher recorded the DTT steps observed to be successfully utilized. Following conclusion of the 10 trials, the student interventionists were thanked and returned to their classroom. Baseline data were collected across staggered baselines with phase changes from baseline to intervention dependent upon stability and trend of intervention integrity data. 2.4.3. Intervention Prior to the intervention phase, student interventionists were trained to implement the DTT protocol by a graduate student researcher. Training consisted of student interventionist review of written instructions (see Appendix A), a review and discussion of procedures with the researcher, modeling of DTT by researcher, and behavioral rehearsal with a researcher. Steps for facilitation of DTT presented to student interventionists included: (a) placing reinforcers out of the participant’s reach; (b) placing teaching stimuli in front of the participant; (c) gaining the participant’s attention; (d) presenting a clear SD for skill use; (e) utilizing and fading prompts to elicit the target skill from the participant; (f) providing consequences dependent upon participant response (i.e., providing reinforcement for correct responding, withholding reinforcement for errors, regaining the participant’s attention when inattentive); (g) allowing for an intertrial interval of 3–5 s at the end of each trial; and (h) correct recording of data. Although data were not collected on whether student interventionists rotated the target stimuli across the array presented to participants with ASD, corrective feedback was provided immediately after the session was complete and immediate before the following session if a failure to rotate stimuli was observed. Student interventionists were trained to utilize a rapid prompt fading process in order to simplify decision making and reduce confusion with regards to when a prompt should or should not be faded based on the responding of the participant with ASD. Student interventionists were instructed to begin their sessions with a full physical prompt on the first trial, a point prompt on the second trial, and allow the student to respond independently by the third trial. Based on the response of the participant with ASD, the student interventionist was instructed to either continue to allow for independent responses or use the last prompt that was effective with evoking a correct response. Since a prompt was initially provided for the first two trials of a session, the highest rate of unprompted responses a participant with ASD could achieve was 80%. Once participants had demonstrated the ability to respond independently and correctly, the experimenters instructed student interventionists to use the point prompt step from the DTT protocol for the first trial and allow independent responding starting with the second trial. In some instances, the participants with ASD responded correctly before the student interventionist could provide a prompt. In this situation, the student interventionists were instructed to record the response as correct, provide immediate reinforcement, and proceed to the next trial. During behavioral rehearsal, performance feedback was provided as necessary, with behavioral rehearsal being continued until participants demonstrated 80% accuracy. Due to the nature of the multiple baseline design, student interventionists were trained at different times throughout the study; and therefore, they were asked not to discuss or demonstrate the procedures to the other student interventionists who had not yet been trained. Training in DTT procedures was completed in one session for all participants, approximately 30 min in duration, and implementation of DTT procedures occurred within one day of training. During each training session, student interventionists were introduced to the training environment. All required stimuli and reinforcers were present in the training setting. Student interventionists were required to prepare the teaching environment by placing the bin of reinforcers out of the participant’s reach, placing teaching materials in front of the

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participant, stop the participant from playing with preferred items, and obtain the participant’s attention. Following preparation of the teaching environment, student interventionists were to present 10 trials of the target skill using the steps learned during training (see Table 1). Intervention integrity and participant response data collected for intervention phases were collected in a manner identical to baseline sessions, with the exception of student interventionists receiving performance feedback at the conclusion of each DTT session. If student interventionists demonstrated intervention integrity less than 80% during a DTT session, they were retrained immediately prior to the next intervention session. Retraining consisted of a review of the written instructions and behavioral rehearsal with a researcher. Intervention sessions were conducted approximately twice per week following the same 30-min format as the baseline sessions with both Jimmy and Ritchie receiving DTT simultaneously. These sessions were designed to supplement the regular instruction both students were already receiving from their classroom teacher. Intervention was terminated following three consecutive sessions in which both intervention integrity and correct/ independent responding were observed to be greater than 90%. Mastery criterion for target skills was selected due to IEP objectives indicating correct/independent responding at 90% or greater for three consecutive teaching sessions. Additionally, student interventionists were replaced by a different student interventionist who had previously met mastery criterion if extended implementation of peer-mediated DTT failed to produce improvements in correct/ independent responding by the target student or if consistent errors in DTT administration persisted following error correction. For example, Ginny demonstrated the most inconsistent adherence to the DTT protocol. Four of her fourteen days as interventionist saw treatment integrity drop below 80%, the most of any student interventionist, despite corrective feedback. The majority of Ginny’s lapses in treatment adherence (55.8%) involved the provision and fading of prompts as outlined in the intervention protocol. These data, coupled with the low rate of acquisition exhibited by Ritchie for the skill Ginny was teaching, provided an impetus to change the student interventionist teaching this skill to Ritchie. Angelina, who had already taught Ritchie to mastery criterion on another skill, was chosen to replace Ginny. No other student interventionists were replaced throughout the duration of the study. 2.5. Interobserver agreement Interobserver agreement (IOA) was obtained for intervention integrity and participant responding through observation of DTT sessions by a second researcher. IOA for intervention integrity and participant responding was collected for 50% of DTT sessions facilitated by Angelina, 51% for Ginny/Angelina, 46% for Jack, 35% for Andrew, 28% for Katie, and 32% for Alicia. Average IOA for intervention integrity was found to be 92% (range = 77–100%) for Angelina, 94% for Ginny (range = 90–100%), 93% for Jack (range = 78–100%), 96% for Andrew (88–100%), 99% for Katie (95–100%), and 96% for Alicia (84–100%). Average IOA for participant responding was 90% for Angelina (range = 50–100%), 94% for Ginny (range = 90–100%), 88% for Jack (range = 50–100%), 89% for Andrew (range = 60–100%), Katie (range = 60–100%), and 96% for Alicia (range = 80–100%). 2.6. Data analysis Intervention effects on intervention integrity and correct/independent responding were evaluated through visual analysis of level, trend, and variability of the data. In addition to visual analysis of data, Tau–U, a nonparametric single case effect size, was calculated to determine the magnitude of the intervention effect. Tau–U, a family of four indices that are based on Kendall’s Rank Correlation and Mann–Whitney U, is a conservative estimate of intervention effect as it allows for the control of trends in the baseline and intervention phases (Parker, Vannest, Davis, & Sauber, 2011). Tau–U scores range between 0.00 and 1.00 and represent the percentage of data that improved between baseline and treatment. Although no interpretation guidelines for Tau–U currently exist, because Tau–U is a similar yet more conservative effect size estimate than Nonoverlap of All Pairs (NAP; Parker & Vannest, 2009), the NAP interpretation guidelines were used in this analysis. As such, Tau–U scores between 0.00 and 0.65 are interpreted as weak intervention effects, scores between 0.66 and 0.91 as moderate effects, and scores between 0.92 and 1.00 are interpreted as strong effects (Parker & Vannest, 2009). For a detailed description of calculation of Tau–U, see Parker et al. (2011). 3. Results 3.1. Effect of interventionist training on intervention integrity The primary research question addressed the functional relationship between the training each student interventionist received in the implementation of DTT and the integrity with which they implemented the intervention procedures over the course of the study. It was hypothesized that student interventionists would demonstrate treatment adherence above baseline levels following training. Overall, visual analysis indicates that training had a large effect on treatment adherence; integrity during baseline remained at near-zero levels for each peer interventionist and no overlapping data were observed from baseline to intervention for all student interventionists. The overall effect size of the training procedures on treatment adherence across all six participants indicated a large effect (Tau–U = 1.00, 95% CI = 0.75–1.00, p < .001). Data from each student interventionist are presented individually below.

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3.1.1. Intervention integrity, Angelina The top panel of Fig. 1 presents Angelina’s treatment adherence data. Visual analysis of Angelina’s treatment adherence data reveals a low and stable baseline. Following training, a large and immediate increase in treatment adherence above baseline levels was observed. An increasing and relatively stable trend in adherence continued throughout the treatment phase. The effect size of DTT training on Angelina’s treatment adherence was large (Tau-U = 1.0, 95% CI = 0.44–1.00, p < .001).

[(Fig._1)TD$IG]

3.1.2. Intervention integrity, Ginny The middle panel of Fig. 1 presents Ginny’s treatment adherence data. Visual analysis of Ginny’s treatment adherence data reveals a low and relatively stable baseline. Following training, a large and immediate increase in treatment adherence was observed. This increase in adherence continued throughout the treatment phase with moderate variability but maintained well above baseline levels. Following the switch in student interventionists from Ginny to Angelina, Ginny was no longer implementing the intervention; therefore, data following this change were not included in Ginny’s treatment adherence analysis. The effect size of DTT training on Ginny’s treatment adherence was large (Tau–U = 1.00, 95% CI = 0.57–1.00, p < .001). 3.1.3. Intervention integrity, Jack The bottom panel of Fig. 1 presents Jack’s treatment adherence data. Visual analysis of Jack’s treatment adherence data reveals a low and stable baseline. Following training, a large and immediate increase in treatment

Fig. 1. Treatment integrity, Angelina, Ginny/Angelina, and Jack.

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adherence above baseline levels was observed. This increase in treatment adherence remained relatively stable throughout the treatment phase. The effect size of DTT training on Jack’s treatment adherence was large (Tau–U = 1.0, 95% CI = 0.63–1.00, p < .001). 3.1.4. Intervention integrity, Andrew The top panel of Fig. 2 presents Andrew’s treatment adherence data. Visual analysis of Andrew’s treatment adherence data reveals a relatively low baseline with a slightly increasing trend present. Following training, a large and immediate increase in treatment adherence above baseline levels was observed. This increase in adherence continued throughout the treatment phase with moderate variability but maintained well above baseline levels. The effect size of DTT training on Andrews’s treatment adherence was large (Tau–U = 1.00, 95% CI = 0.50–1.00, p < .001). 3.1.5. Intervention integrity, Katie The middle panel of Fig. 2 presents Katie’s treatment adherence data. Visual analysis of Katie’s treatment adherence data reveals a low and relatively stable baseline. Following training, a large and immediate increase in treatment adherence above baseline levels was observed. This increase in level was associated with a corresponding increase in variability but eventually stabilized toward the end of the treatment phase. The effect size of DTT training on Katie’s treatment adherence was large (Tau–U = 1.00, 95% CI = 0.62–1.00, p < .001).

[(Fig._2)TD$IG]

Fig. 2. Treatment integrity, Andrew, Katie, and Alicia.

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3.1.6. Intervention integrity, Alicia The bottom panel of Fig. 2 presents Alicia’s treatment adherence data. Visual analysis of Alicia’s treatment adherence data reveals a low and stable baseline. Following training, a large and immediate increase in treatment adherence was observed. An upward and relatively stable trend in adherence continued throughout the treatment phase. The effect size of DTT training on Alicia’s treatment adherence was large (Tau–U = 1.00, 95% CI = 0.65–1.00, p < .001). 3.2. Effects of peer-mediated DTT on correct/independent responding The second research question addressed the functional relationship between the peer-mediated DTT procedure and correct/independent responding of participants with ASD. It was hypothesized that implementation of peer-mediated DTT would be associated with an increase in participants’ correct/independent responding above baseline levels. Overall, visual analysis indicates that implementation of peer-mediated DTT had a large effect on correct/independent responding; correct/ independent responding and prompted responding during baseline remained at near-zero levels for each participant. Following introduction of peer-mediated DTT, immediate increases in prompted responding were observed across participants. For all participants, increases in correct/independent responding were observed following several sessions of increased levels of prompted responding, with prompted responding decreasing as participants reached mastery criteria (three consecutive sessions of 90% or greater correct/independent responding). The overall effect size across both participants indicated a moderate effect (Tau–U = 0.83, 95% CI = 0.58–1.00, p < .001). Data from each participant are presented individually below. 3.2.1. Correct/independent responding, Jimmy Fig. 1 presents Jimmy’s correct/independent responding and prompted responding data across the skills taught using the peer-mediated DTT procedure. Across all three skills, peer-mediated DTT was associated with a moderate overall effect size for correct/independent responding (Tau–U = 0.81, 95% CI = 0.47–1.00, p < .001). Data from each skill are presented individually below. As shown in the top panel of Fig. 3, visual analysis of Jimmy’s object-to-object matching correct/independent responding data revealed a stable baseline phase with no correct/independent or prompted responding. Jimmy’s object-to-object matching correct/independent responding initially remained at baseline levels for several sessions once peer-mediated DTT was implemented, while prompted responding demonstrated a large increase. Following several sessions of high levels of prompted responding, Jimmy demonstrated a variable yet rapid increase in correct/ independent responding. Once correct/independent reached 100%, it remained stable until the mastery criterion was met. The effect size of the peer-mediated DTT procedure on Jimmy’s correct/independent responding for object-toobject matching is moderate (Tau–U = 0.56, 95% CI = 0.00–1.00, p < .05). As shown in the middle panel of Fig. 3, visual analysis of Jimmy’s 2D receptive identification data revealed a stable baseline with no correct/independent or prompted responding. Jimmy’s 2D receptive identification correct/independent responding initially remained at baseline levels, whereas prompted responding demonstrated increased, yet variable, data. Following several sessions in which high rates of prompted responding were demonstrated, a small increase in correct/independent responding was observed. Following a change in student interventionist, Jimmy demonstrated a rapid increase in correct/independent responding above baseline levels that became highly variable as the phase continued before stabilizing at 100% until the mastery criterion was met. The effect size associated with the peermediated DTT procedure on 2D receptive identification correct/independent responding is moderate (Tau–U = 0.67, 95% CI = 0.27–1.00, p < .001). As shown in the bottom panel of Fig. 3, visual analysis of Jimmy’s picture-to-picture matching data revealed a relatively stable baseline with nearly no correct/independent responding and no prompted responding. Picture-to-picture correct/independent responding and prompted responding demonstrated an immediate increase above baseline levels once peer-mediated DTT was implemented and a consistent upward trend in correct/independent responding was apparent. Variability of correct/independent responding increased as the intervention phase continued before stabilizing above 80% until the mastery criterion was met. The effect size associated with the peer-mediated DTT procedure on picture-to-picture correct/independent responding is large (Tau–U = 1.00, 95% CI = 0.63–1.00, p < .001). 3.2.2. Correct/independent responding, Ritchie Fig. 2 presents Ritchie’s correct/independent responding and prompted responding data across the skills taught using the peer-mediated DTT procedure. Across all three skills, peer-mediated DTT yielded a moderate effect on correct/independent responding (Tau–U = 0.88, 95% CI = 0.54–1.00, p < .001). Data from each skill are present individually below. As shown in the top panel of Fig. 4, visual analysis of Ritchie’s 2D receptive identification data revealed a stable baseline phase with no correct/independent or prompted responding. Upon implementation of the peer-mediated DTT procedure, Ritchie’s 2D receptive identification demonstrated a small but immediate increase in correct/independent responding, and a large, but variable increase in prompted responding. A consistent but variable increasing trend in correct/independent responding was evident as the intervention phase continued before stabilizing at 100% until the mastery criterion was met. The effect size of the peer-mediated DTT procedure on Ritchie’s 2D receptive identification correct/independent responding is moderate (Tau–U = 0.82, 95% CI = 0.33–1.00, p < .001).

[(Fig._3)TD$IG]

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Fig. 3. Skill accuracy, correct/independent and prompted responses, Jimmy.

As shown in the middle panel of Fig. 4, visual analysis of Ritchie’s object-to-object matching data revealed a stable baseline with no correct/independent or prompted responding. Ritchie’s object-to-object identification correct/independent responding demonstrated a large increase in level once the peer-mediated DTT procedures were implemented, with a small increase in prompted responding. Moderate variability in correct/independent responding was evident as the intervention phase continued before correct/independent responding stabilized at 100% and the mastery criterion was met. The peermediated DTT procedure on object-to-object matching correct/independent responding was associated with a moderate effect (Tau–U = 0.89, 95% CI = 0.51–1.00, p < .001). As shown in the bottom panel of Fig. 4, visual analysis of Ritchie’s picture-to-picture matching data revealed a relatively stable baseline with nearly no correct/independent responding and no prompted responding. Although there was not an immediate increase in correct/independent responding between baseline and implementation of the peer-mediated DTT procedure, picture-to-picture matching correct/independent responding demonstrated a consistent upward trend with little variability as the intervention phase continued before the mastery criterion was met. Prompted responding demonstrated an immediate increase following implementation of peer-mediated DTT, with a decreasing trend throughout the intervention phase. The effect size associated with the peer-mediated DTT procedure on correct/independent responding for picture-topicture matching is large (Tau–U = 0.91, 95% CI = 0.49–1.00, p < .001). 3.3. Treatment acceptability Data regarding the acceptability of the intervention procedures were collected all six student interventionists responsible for implementing DTT. Following the completion of the study, each student interventionist was asked to complete a BIRS regarding their involvement with the intervention. Overall, the peer-mediated DTT procedure was rated positively by the student interventionists (M = 5.37, SD = 0.79; Agree) on the factors of acceptability (M = 5.40, SD = 0.87; Agree), effectiveness (M = 5.16, SD = 0.83; Agree), and time (M = 5.42, SD = 0.58; Agree).

[(Fig._4)TD$IG]

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Fig. 4. Skill accuracy, correct/independent and prompted responses, Ritchie.

4. Discussion The purpose of the current study was to evaluate the utility of a peer-mediated DTT protocol. Specifically, peer-mediated DTT was investigated in the context of the school setting in terms of implementation integrity, skill acquisition, and acceptability. Overall, functional relationships were demonstrated between training of DTT procedures and student interventionist treatment adherence and between implementation of peer-mediated DTT and skill acquisition by target students. This supports the finding of Schreibman et al. (1983), who found elementary-age student interventionists to implement a DTT protocol with high levels of integrity, resulting in the acquisition of target academic skills in children with ASD. The current findings expand upon previous research by providing preliminary evidence for the effectiveness of peermediated DTT within the context of the schools. Although the 30-min semiweekly DTT sessions utilized in the current study were far less rigorous than some DTT programs (e.g., Lovaas, 1987b), the current results suggest that these relatively infrequent sessions were sufficient for both target students to master all three skills addressed through the intervention; however, more frequent sessions (i.e. daily) and/or more gradual prompt fading may have allowed Jimmy and Ritchie to master their respective skills in a shorter amount of time. These results cannot be taken out of the school-based service delivery context, which often must consider the availability of funding, time, and intervention personnel when evaluating the usefulness of an intervention. Teachers’ daily instructional demands often conflict with the limited amount of time they have to complete them. Although DTT is effective and may result in substantial academic benefit for students with ASD (Leaf & McEachin, 1999; Lovaas & Smith, 2003; Smith, 2001; Sturmey & Fitzer, 2007), special education teachers may not have time to implement an intervention like DTT in addition to their regular instructional requirements. As such, Steege et al. (2007) cautioned against using DTT in schools because of the resources required for implementation of such an intensive intervention. The results of the current study also provide preliminary evidence that elementary school students can be trained effectively to implement DTT, suggesting that alternative implementation options may be available to school personnel wishing to establish a DTT

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program within the classroom. It might be most beneficial for schools to conceptualize students as supplementary interventionists within an established adult-mediated DTT program to increase the amount of service already provided to the target student and promote generalization by training sufficient exemplars (Stokes & Baer, 1977). As demonstrated in this study, peer-mediated DTT may improve the efficiency of DTT within school settings by taking advantage of an abundant resource in schools, other students, and increasing the number of available interventionists. The present study placed an adult into a supervisory role, instead of an intervention role, allowing them to supervise two simultaneous peer-mediated DTT sessions. By implementing DTT in this way, a single adult (e.g. classroom aide, paraprofessional) may be able to supervise several student interventionists at once, increasing a school’s capacity to provide these otherwise time intensive services. By consolidating provision of DTT services to several students into a single peer-mediated small group session format it might be feasible for schools to provide a more intense (i.e. more hours per week) DTT program than would be possible otherwise. Outcomes in the current study indicate that student interventionists implemented the DTT protocol with high procedural integrity, indicating that a brief training session consisting of written and verbal instructions, modeling, rehearsal, performance feedback, and subsequent feedback/re-training may be sufficient to promote high integrity in basic DTT procedures. Due to the high intervention integrity and subsequent skill acquisition by participants with ASD, results of the current study indicate that peer-mediated DTT may represent a feasible option in a school setting in which limited time and resources prohibit the use of DTT to address academic skills in children with ASD. Several other potential benefits of peer-mediated DTT within school settings are noted. First, student interventionists trained the target students in their natural environment (i.e., self-contained special education classroom). By conducting the DTT intervention in the student’s natural environment, where they are expected to exhibit the trained skills and naturally maintaining contingencies for target skill use exist, the likelihood of participants with ASD engaging in those skills is increased (e.g., Stokes & Osnes, 1989). Additionally, Jimmy’s skill acquisition results should be considered in light of the fact that he frequently engaged in disruptive behaviors during the peer-mediated DTT sessions. Students with ASD commonly exhibit problem behaviors similar to those of Jimmy (e.g., motor stereotypy, non-compliance, out of seat behavior; e.g., O’ Neill, Jenson, & Radley, 2014), potentially increasing the difficulty associated with implementing a DTT program. Although no objective measures of student behavior were taken and only one of the two target students engaged in significant problem behaviors, the student interventionists working with Jimmy were able to navigate his problem behavior while implementing DTT with a high degree of integrity. This suggests that student interventionists may be able to implement DTT with high integrity even when faced with challenging behavior; however, because problem behavior can vary greatly between individuals in topography, function, and intensity, more research is needed before definitive statements about the effectiveness of peer-mediated DTT for students engaging in problem behavior. It is also important to note the social validity of peer-mediated DTT in addressing IEP objectives of students with ASD. Although Jimmy and Ritchie missed approximately 30 min of instructional time during each DTT session, both students were taught academic skills that addressed objectives on each of their IEPs, with both students achieving mastery levels during peer-mediated DTT. Demonstrating attainment of IEP objectives is paramount to determining whether a special education student is making progress in their educational environment. Although both Jimmy and Ritchie mastered all of their respective target skills in approximately the same amount of time (M = 18.7 and M = 18.3 sessions, respectively) there were substantial discrepancies between skills within each student’s data. Jimmy mastered Object–Object matching in 9 sessions, Picture–Picture matching in 17 sessions, and Receptive Identification in 30 sessions; although, once Ginny was replaced by Angelina, Jimmy mastered Receptive Identification in 16 sessions. Ritchie mastered Picture–Picture matching in 13 sessions, Object–Object matching in 19 sessions, and Receptive Identification in 23 sessions. There is no easily identifiable explanation for this discrepancy other than the relative ease or difficulty of the skill being taught. Both students took the longest to master receptive identification, which might be reflective of their limited verbal abilities. The strengths and positive results of the current study must also be conceptualized in light of several limitations. First, data collection procedures required the researchers to be present and in close proximity to the student interventionists and target students during DTT sessions. Although researchers engaged in minimal interaction with the students, unknown levels of reactivity may have influenced student behaviors and subsequent outcomes. Consequently, it is possible that the same high levels of integrity and acquisition would not occur in a situation in which peer-mediated DTT was being conducted without such close monitoring; however, the minimal level of interaction during DTT between researchers and student interventionists suggests that similar results may be obtained with reduced supervision. Additionally, peermediated interventions are rarely, if ever, implemented without adult supervision in practice and the minimal level of support provided to student interventionists in this study reflects what would typically be provided if the intervention were being implemented outside the context of an empirical study. Second, teacher acceptability data were not obtained. As such, it is unknown whether the teachers of the student interventionists and of the participants with ASD found this intervention and its procedures acceptable considering the required changes in classroom environment, routine, and instruction time. Future studies should collect data on intervention acceptability from teachers of both the target students and student interventionists, allowing for further assessment of the social validity of peer-mediated DTT in a school setting. Lastly, no probes of maintenance or generalization were collected. Follow-up measures of intervention integrity and student skill acquisition could assess the robustness of the procedures and the amount of follow-up training necessary across a semester or school year. Additionally, the assessment of how well student interventionists can generalize DTT implementation across settings, target students or skills would expand the DTT and peer-mediated intervention literature.

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5. Conclusion The current study demonstrates that elementary-age students can be taught to implement a basic DTT protocol with high levels of integrity following brief training. Additionally, peer-mediated DTT resulted in improvements in academic skills previously identified as learning objectives on participants’ IEPs. As substantial barriers exist for implementation of DTT within school settings (e.g., Eikeseth, 2010; Skokut et al., 2008; Steege et al., 2007), peer-mediated DTT may improve intervention feasibility in school settings. Although additional research is needed to determine the effects and generalizability of school-based, peer-mediated DTT, the current study indicates that peers may implement basic DTT protocols with a high degree of integrity, producing measurable improvements in academic skills of children with ASD. Appendix A. Peer training script Note: If the student tries to leave the teaching area, begins to engage in problem behavior, or does not want any of the available toys or snacks, stop teaching. Before you start: 1. 2. 3. 4.

Place bin of toys/snacks out of the student’s reach. Place teaching materials in front of the student. Stop the student from playing with preferred items. Get the student’s attention by patting your hands in your lap and say: ‘‘Get Ready!’’

Teaching: 1. 2. 3. 4. 5. 6. 7.

Present your instruction: (Ex: ‘‘Match it,’’ ‘‘Where’s the. . ..’’ ‘‘Show me. . .’’ ‘‘Give me. . .’’ ‘‘What is it?’’) Guide the student’s hand to match/touch/or give the card/object with the correct answer. Praise him by saying something like: ‘‘GOOD JOB/GREAT WORK/WAY TO GO!’’ Record N on data sheet. Present your instruction: (Ex: ‘‘Match it,’’ ‘‘Where’s the. . ..’’ ‘‘Show me. . .’’ ‘‘Give me. . .’’ ‘‘What is it?’’) Point to the correct card/object. If the student matches/touches the right card/object after you point to it:  Immediately give him the reward and praise him by saying something like: ‘‘GOOD JOB/GREAT WORK/WAY TO GO!’’  Record N on data sheet  Go to step 8

If the student matches/touches the wrong card/object, go back and do steps 1–7. 8. Present your instruction: (Ex: ‘‘Match it,’’ ‘‘Where’s the. . ..’’ ‘‘Show me. . .’’ ‘‘Give me. . .’’ ‘‘What is it?’’) 9. If he matches/touches the right picture/object with *NO HINTS*  Immediately give him a reward and praise them by saying something like: ‘‘GOOD JOB/GREAT WORK/WAY TO GO!’’  Record Y on the data sheet If the student matches/touches the wrong card/object  Record N on the data sheet  Go back and do steps 5–7 10. Repeat these steps until data sheet is completed. If the student makes a mistake: If the student touches multiple cards ITS OKAY! follow these steps: 1. 2. 3. 4. 5. 6.

Place the student’s hands in his lap and count to 2 MISSISSIPPI. Present your instruction: (Ex: ‘‘Match it,’’ ‘‘Where’s the. . ..’’ ‘‘Show me. . .’’ ‘‘Give me. . .’’ ‘‘What is it?’’) Guide the student’s hand to match/touch/or give the card/object with the correct picture/match. Praise him by saying something like: ‘‘GOOD JOB/GREAT WORK/WAY TO GO!’’ Record N on data sheet. Repeat steps 5–7.

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