An Analysis of Naturalistic Interventions for Increasing Spontaneous Expressive Language in Children With Autism Spectrum Disorder

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1 614837SEDXXX / The Journal of Special EducationLane et al. research-article2015 Article An Analysis of Naturalistic Interventions for Increasing Spontaneous Expressive Language in Children With Autism Spectrum Disorder The Journal of Special Education 2016, Vol. 50(1) Hammill Institute on Disabilities 2015 Reprints and permissions: sagepub.com/journalspermissions.nav DOI: / journalofspecialeducation.sagepub.com Justin D. Lane, PhD, BCBA-D 1, Rebecca Lieberman-Betz, PhD 2, and David L. Gast, PhD 2 Abstract The purpose of this review was to identify naturalistic language interventions for increasing spontaneous expressive language (defined in this review as absence of verbal prompt or other verbalization from adults or peers) in young children with autism spectrum disorder. Also, the methodological rigor and effectiveness of each study were evaluated to determine which interventions confidently led to increases in the target behavior. A total of 24 studies that included 45 participants, 2 to 9 years of age, used a naturalistic language intervention. When using What Works Clearinghouse (WWC) guidelines to evaluate design standards, 50% of studies had adequate rigor and 33% of those studies demonstrated positive effects in the target behavior. In addition, the components of each intervention were coded and grouped by function. Implications for teachers, practitioners, and researchers are provided. Keywords naturalistic interventions, expressive language, communication, autism spectrum disorder Children with autism spectrum disorder (ASD) display marked impairments in age-appropriate communication skills (Strain, McGee, & Kohler, 2001; Wetherby & Woods, 2006). Delays in expressive communication are especially prevalent among young children with ASD, with approximately 40% to 50% of children never developing functional speech (Zager, Wehmeyer, & Simpson, 2012). Expressive language delays affect children s ability to meaningfully share wants and interests with social partners; broader implications include decreased opportunities for peer-topeer interactions (Wetherby & Woods, 2006) and increased dependence on parents/caregivers across the lifespan, a source of stress for many families (cf. Hayes & Watson, 2013). Given the immediate and long-term importance of improving expressive language in children with ASD, intensive intervention is often necessary to remediate delays and improve a child s developmental trajectory. History of Expressive Language Instruction Historically, instruction for children with ASD occurred in a one-to-one arrangement of an adult and child in a clinical setting. In this context, adults typically conducted multiple discrete trials at a table to teach children to label an item or imitate a specific word or phrase, which was followed by access to an unrelated item (e.g., candy for imitating the word ball ) to reinforce verbalizations. Although effective, children with ASD did not readily display target behaviors outside of these restricted instructional contexts. This lack of generalization was linked to social and communication delays commonly displayed by young children with ASD (e.g., rigidity; difficulties recognizing shared features of instructional materials vs. those available in typical environments; Zager et al., 2012). To address this issue, naturalistic language interventions, such as incidental teaching, were recommended to promote acquisition and generalization of expressive language (Hart & Risley, 1968; Pierce & Schreibman, 1995). Naturalistic language interventions include a combination of procedures from the applied behavior analysis (ABA) literature (e.g., prompting, reinforcement, shaping) and strategies based on a social interactionist approach to language 1 University of Kentucky, Lexington, USA 2 University of Georgia, Athens, USA Corresponding Author: Justin D. Lane, Early Childhood & Special Education, University of Kentucky, 229 Taylor Education Building, Lexington, KY 40506, USA. justin.lane@uky.edu

2 50 The Journal of Special Education 50(1) learning (e.g., recasts, responsive communication; Kaiser & Trent, 2007). Adults embed opportunities for expressive language in social exchanges and everyday routines and activities of the child (e.g., requesting toys during free play in a preschool classroom; taking turns with large equipment on the playground; Kaiser & Grim, 2005; Kaiser & Trent, 2007). The term embed refers to including instruction during typical activities, with adults providing learning opportunities across contexts (Wolery, Anthony, Caldwell, Snyder, & Morgante, 2002). This is especially important for children with ASD, who are likely to require multiple opportunities to recognize when and how to use social-communication skills in dynamic environments (Ledford & Wolery, 2013a, 2015). Current Recommendations Naturalistic language interventions are now widely recommended for children with ASD (e.g., Division for Early Childhood [DEC] of the Council for Exceptional Children, 2014; National Research Council, 2001; Wong et al., 2014). A recent report by Schreibman and colleagues (2015) outlined the rich history of naturalistic language interventions for children with ASD but stressed the need to further evaluate interventions, as well as identify critical components that lead to meaningful change in expressive communication, especially expressive language. In conjunction with these recommendations, parents of children with ASD continue to request services to increase their child s spontaneous expressive language. Expressive language delays are often one of the first reasons parents of children with ASD seek professional support (Zager et al., 2012). Given the importance of identifying and analyzing effective naturalistic interventions for children with ASD, along with parents who want to promote age-appropriate expressive language in their children, a review of naturalistic language interventions is warranted. The purpose of this review was to identify naturalistic language interventions that specifically targeted increasing spontaneous expressive language in children with ASD. Descriptive information regarding participants, components of interventions, and experimental designs were reviewed. In addition, we asked the following questions: (a) Are naturalistic language interventions effective for increasing spontaneous expressive language in children with ASD? (b) If effective, for whom and under what conditions? (c) Do studies have adequate rigor to support findings? And (d) Following an evaluation of rigor, what are the common features of effective and ineffective interventions? Method A search for naturalistic language interventions for children with ASD was conducted using ERIC, PsycINFO, Education Research Complete, and Medline databases. The following keywords were used with autis* when searching for articles: naturalistic language interventions, communication interventions, naturalistic teaching strategies, naturalistic language approaches, naturalistic language strategies, or language intervention. Additional keywords were used to search for specific interventions: DIR Floortime, Early Start Denver Model, Enhanced Milieu Teaching, Hanen More Than Words, Incidental Teaching, Mand-Model, Milieu Teaching, Joint Attention Intervention, Preschool Autism Communication Trial, Pivotal Response Training (PRT), Responsive Interaction, Social Interaction Project, and Social Pragmatic Intervention. Throughout this review, the term article refers to each published manuscript and study refers to individual designs within each article (e.g., one article may include two singlecase designs, which can be independently evaluated). The first author reviewed articles for the following preliminary inclusion criteria: (a) the researchers used a single-case design or a quasi-experimental or experimental group design and (b) the researchers were attempting to increase spontaneous verbalizations in at least one participant with ASD (participants could be at risk for ASD if within the early childhood age range, birth to 8 years of age). Following this initial review, 49 articles were identified and further reviewed using the following inclusion criteria: (a) The results of the intervention s effect on spontaneous verbalizations (absence of a prompt or other verbalization from an adult or peer; Charlop- Christy & Jones, 2006) were reported separately from other dependent measures (not collapsed with prompted responses) and (b) the cue for spontaneous verbalizations focused on that behavior only (e.g., excluded if eye contact was required). Eleven of the 49 articles met both inclusion criteria. Finally, the 11 remaining articles were examined and excluded if (a) the primary intervention was an alternative and augmentative communication (AAC) device or the Picture Exchange Communication System (PECS), (b) adults did not use stimulus materials based on child interest or selection, (c) adults did not use external or social reinforcers, and (d) trials did not occur in natural settings or settings designed to parallel natural settings. One article was excluded due to lack of child choice (or preference) with stimulus materials. Ten of the 11 articles met all criteria. The first author reviewed all articles, and the second author reviewed 20% of the 49 articles (n = 10); a person blind to the purpose of the review randomly selected these 10 articles. Agreement was 80%, with one disagreement in two articles (stimulus materials [n = 1], setting [n = 1]). Disagreements were reviewed and reconciled by the first and second author. In addition, the first author conducted an ancestral search of each of the 10 articles and identified one additional article meeting inclusion criteria (N = 11). Within 10 of 11 articles, 23 single-case design studies were used to analyze an intervention s effect on spontaneous verbalizations and one of 11 articles used a group design (Venker, McDuffie, Weismer, & Abbeduto, 2012).

3 Lane et al. 51 Descriptive Information The first author coded descriptive information reported for participants and the independent variable in each article, as well as the experimental design for each study. Descriptive information coded for participants included the following: (a) demographic information: age of participants at the start of the study, with ages converted to years, and race and ethnicity; (b) preintervention communication skills: spontaneous verbalizations and other related communicative behaviors prior to introducing the intervention; (c) communication evaluations: coded if an article reported scores from evaluations conducted prior to beginning the intervention; and (d) other descriptive information: diagnostic descriptors (severity of ASD) or social (e.g., aggression) or play behaviors (e.g., appropriate material use) related to the format of sessions (child-led, naturalistic activities that included age-appropriate materials). The independent variable was coded as follows: (a) implementers: person who conducted the intervention, (b) context: location of the intervention sessions, (c) components of the independent variable: based on reported components in the Method section of each article ( Results and Discussion sections were also reviewed to ensure any modifications to the intervention were identified), and (d) dosage: number of trials or opportunities per session, length of sessions, and frequency of sessions. Finally, the first author reviewed each graph to ensure that the reported experimental design corresponded with the actual design used to evaluate the intervention. Analysis of Interventions Single-case designs. The first and second author independently analyzed the methodological rigor (design standards) and effectiveness of each single-case study using What Works Clearinghouse (WWC) guidelines (Kratochwill et al., 2010). Design standards refer to the following: (a) Researchers systematically introduced or manipulated the naturalistic language intervention, (b) interobserver agreement (IOA) was collected for at least 20% of sessions and (c) was 80% or higher, (d) the researchers attempted to demonstrate three or more demonstrations of effect, and (e) the researchers collected at least 5 data points per condition (or comparisons for an alternating treatments design). A study that included all of these criteria was classified as meets design standards without reservation, and a study that included all of these criteria but only 3 data points per condition was classified as meets design standards with reservation; all other studies were classified as not meeting design standards. Regarding effectiveness of an intervention, if a study met design standards without or with reservations, visual analysis of graphs occurred (e.g., assessment of trend, level, and variability; Gast & Ledford, 2014; Kratochwill et al., 2010). Findings were classified as (a) no evidence less than three demonstrations of effect, (b) moderate evidence three demonstrations of effect with one non-effect, or (c) strong evidence three demonstrations of effect with no non-effects (Kratochwill et al., 2010). Currently, there are no guidelines for evaluating evidence of comparison designs; for a single study using such a design (Ingersoll, 2010), the authors compared all possible combinations of interventions (e.g., A to B, B to C, C to A) and used a dichotomous code of differentiated data (minimal to overlap) or no clear differentiation (majority of data overlap). Group design. The first and second author evaluated Venker et al. (2012) using WWC (2012) group design guidelines for randomized controlled trials (; O Keefe, Slocum, Burlingame, Snyder, & Bundock, 2012). Methodological rigor was assessed as follows: (a) Groups were randomized, (b) overall and (c) differential attrition did not indicate bias, (d) groups were equivalent during baseline conditions, (e) reliability data, such as intraclass correlation coefficients, met minimum standards, and (f) no confounds that could have influenced findings were identified. Evaluation of evidence occurred if the study met design standards without (meets all criteria) or with reservations (overall and differential attrition indicates bias but all other criteria are met). Tests of statistical significance were evaluated and classified as follows: (a) statistically significant positive effect, (b) substantively important positive effect, (c) indeterminate effect, (d) substantively important positive effect, and (e) statistically significant negative effect (WWC, 2012). IOA. IOA was calculated for 100% of studies with 92.2% initial agreement for design standards (10 disagreements; maximum of two disagreements in a single study) and 95.8% initial agreement for evidence of effectiveness (one disagreement). Disagreements were reviewed and reconciled by the first and second author. In addition, even though not required by WWC, the first author visually analyzed all graphs in each single-case study, while a researcher blind to the purpose of the review analyzed 96% of the graphs to determine if a functional relation was present; agreement was 100%. Procedural fidelity. The first author coded whether studies assessed reliable implementation of experimental procedures, with agreement at or above 80%; procedural fidelity was defined as including prescribed components during baseline and intervention conditions, and treatment fidelity was defined as assessing the intervention condition only (Ledford & Wolery, 2013b). Results Descriptive Information Participants. A total of 45 children with ASD, 2 to 9 years of age, participated in studies designed to increase spontaneous

4 52 The Journal of Special Education 50(1) Table 1. Participant Demographics and Preintervention Behaviors. Preintervention behaviors First author N Age (years) Race/ethnicity Communication skills Formal communication evaluations Other descriptive information Charlop-Christy, 2000 Christensen- Sandfort, P1: W/NH P1: LV P1 P3: P1 P3: Displayed challenging behavior; delayed play skills P2: IA/NH P2 P3: NV P3: W/H P1: NV P1 P3: P1: Mild-moderate ASD a ; delayed play skills P2: LV P2: Severe ASD a ; engaged in cooperative play P3: NV P3: Severe ASD a ; displayed challenging behavior; delayed play skills Gillett, P1: W/NH P1 P2: LV P1 P3: P1: Delayed play skills P2: AS/NH P3: NV P2 P3: P3: AA/NH Hemmeter, P1: LV P1: ECD P1: Ingersoll, P1 P2: LV P1 P2: ECD P1: Moderate ASD b P2: Mild ASD b Ingersoll, P1: LV P1 P5: ECD P1 P5: P2 P5: UV Koegel, P1 P2: NV P1 P2: COG P1 P2: Displayed challenging behavior Koegel, P1 P3: LV P1 P3: ECD P1 P3: Displayed challenging behavior Koegel, P1 P3: UV P1 P3: ECD P1 P3: Schreibman, P1 P6: P1 P6: ECD P1 P3: Avoided proximity to others; displayed self-stimulatory behaviors P4 P6: Displayed self-stimulatory behaviors; delayed play skills Venker, P1 P14: P1 P14: ECD P1 P14: Note. P = participant; W = White; NH = non-hispanic; IA = Indian American; H = Hispanic; LV = child displayed limited use of verbalizations; NV = child did not use verbalizations to communicate; ASD = autism spectrum disorder; AS = Asian American; AA = African American; ECD = scores indicated expressive communication delays; UV = child typically used some form of verbalization to communicate; COG = scores indicated cognitive delays. a Childhood Autism Rating Scale (CARS). b Instrument used to verify diagnosis/severity not reported. verbalizations using a naturalistic language intervention, with the majority of participants (N = 42 or 93%) between 2 and 5 years of age. Race and ethnicity were reported for only a few participants in two articles, limiting the utility of this information in the current review. Prior to beginning intervention sessions, participants preintervention communication skills varied, with nine articles reporting some information for 25 participants. Regarding spontaneous verbalizations, 11 participants used only a few sounds, words, or phrases; seven readily used verbalizations to communicate with others; and seven did not use spontaneous verbalizations. Evaluation scores were reported for 36 participants and were either direct measures of expressive communication or composite cognitive scores. All participants displayed expressive communication delays or general developmental delays. Additional descriptors related to severity of diagnosis and social or play behaviors were limited. A description of severity of diagnosis was reported for only 11 participants and ranged from mild to severe classifications. Fifteen participants consistently displayed problem behaviors (e.g., aggression) or other behaviors (self-stimulatory behaviors) that commonly interfered with social interactions and age-appropriate play skills. Finally, nine participants displayed difficulties engaging in age-appropriate play actions with materials (see Table 1). Independent variable. In 11 articles, authors named 10 separate interventions (see Tables 2 and 3), with multiple articles evaluating more than one intervention. The most commonly evaluated intervention was Milieu Teaching (MT) used alone or combined with the Responsive Interaction Intervention (RII). Intervention sessions were typically conducted in a clinic setting or combination of a clinic-based setting with some sessions in participants homes. Interventions either targeted a single form of verbalization (e.g., the question, What s that? )

5 Lane et al. 53 Table 2. Dosage, Context, and Forms of Communication. Dosage First author Named intervention Trials or opportunities (time) Frequency of sessions Implementers Context Forms of verbalizations Fidelity data Charlop-Christy, IT 1 trial 1 a day P H Single T a,b 2000 Charlop-Christy, MITS 6 trials 1 a day P H Single T a,b 2000 Charlop-Christy, DTT 10 trials 1 a day P H Single T a,b 2000 Christensen- MT 2 trials (structured 2 a week (structured T S Single T b Sandfort, 2013 activity) activity) NS (unstructured activity) 2 a week (unstructured activity) Gillett, 2007 NLP NS Three sessions a day, 2 P H/C Multiple T a,b a week Hemmeter, 1994 EMT NS (15 min) Two sessions, 2 a week P C Multiple None Ingersoll, 2010 RI Every s (10 min) One to two sessions a T C Multiple T a day, 2 a week Ingersoll, 2010 MT Every s (10 min) One to two sessions a T C Multiple T a day, 2 a week Ingersoll, 2010 RI + MT RI every s and One to two sessions a T C Multiple T a MT s (10 min) day, 2 a week Ingersoll, 2012 RI Every s (20 min) Three sessions a day, 2 R C Multiple T a,b a week Ingersoll, 2012 MT Every s (20 min) Three sessions a day, 2 R C Multiple T a,b a week Ingersoll, 2012 RI + MT RI every s and Three sessions a day, 2 R C Multiple T a,b MT s (20 min) a week Koegel, 1987 NLP NS 2 a week R C Multiple None Koegel, 1998 PRT NR (30 min) 2 a week T H/C Single None Koegel, 2010 PRT s (60 min) 2 a week R H/C Single None Schreibman, 2009 PRT Average of 1 per min 3 a week R C Multiple T a,b Venker, 2012 MTW NS NS P C Multiple T Note. IT = incidental teaching; P = parents; H = home; T a,b = treatment fidelity collected at least 20% of sessions and was 80% or higher; MITS = modified incidental teaching; DTT = discrete trial training; MT = milieu teaching; T = teachers; S = school; T b = treatment fidelity collected but frequency and data were not reported; NLP = natural language paradigm; NS = not specified; C = clinic; EMT = enhanced milieu teaching; RI = responsive interaction; T a = treatment fidelity collected at least 20% of sessions but data were not reported; R = researchers; PRT = pivotal response training; NR = not reported; MTW = Hanen more than words. or multiple forms of verbalization (e.g., various single words; see Table 2). The components of each named intervention were reviewed and then grouped by function within an intervention session (see Figure 1): Strategies to promote engagement. Adults engaged in activities based on the child s interest and, when possible, avoided redirecting a child to less preferred activities. Adults promoted turn-taking with materials and conversation and allowed the child time to respond. Adults expanded all spontaneous verbalizations by the child and provided verbal models of target sounds, words, or phrases throughout sessions. Strategies to promote verbalizations during planned opportunities. During intervention, adults used an environmental arrangement strategy and, at times, established eye contact to (a) create an opportunity to describe a child s non-verbal communication, (b) expand a current spontaneous verbalization, or (c) evoke a target spontaneous verbalization. Adult prompts to promote verbalizations and responses to verbalizations. All interventions, with the exception of RII, used adult prompts to promote spontaneous verbalizations in young children with ASD. Prompts were typically used following a child initiation or adult-planned opportunity to promote a spontaneous verbalization. Although there were variations in procedures, there were many commonalities. When targeting novel words or phrases, adults immediately presented a full verbal model (0 s delay) of the target or waited 5 to 10 s for a spontaneous verbalization. If adults provided a 0-s delay prompt, in subsequent sessions, adults began using a less intrusive prompt. In contrast, if an adult began instruction with a time delay and it was ineffective, they then provided a more intrusive prompt (e.g., question; model prompt). If

6 54 The Journal of Special Education 50(1) Table 3. Brief Description of Naturalistic Language Interventions. Intervention IT Used in Charlop-Christy and Carpenter (2000) MITS Used in Charlop-Christy and Carpenter (2000) DTT Used in Charlop-Christy and Carpenter (2000) MT Used in Christensen-Sandfort and Whinnery (2013); Ingersoll (2010); Ingersoll, Meyer, Bonter, and Jelinek (2012) RII Used in Ingersoll (2010); Ingersoll et al. (2012) Combined MT and RII Used in Ingersoll (2010); Ingersoll et al. (2012) EMT Used in Hemmeter and Kaiser (1994) MTW Used in Venker, McDuffie, Weismer, and Abbeduto (2012) PRT Used in L. K. Koegel Camarata, Valdez- Menchaca, and Koegel (1998); L. K. Koegel, Koegel, Green-Hopkins, and Barnes (2010); Schreibman, Stahmer, Barlett, and Dufek (2009) NLP Used in Gillett and LeBlanc (2007); R. L. Koegel, O Dell, and Koegel (1987) Summary A procedure that promotes initiations and expands verbal communication during typical activities. A child initiates an interaction with a verbal or non-verbal request and an adult prompts an elaboration to expand the child s communicative repertoire, using a more intrusive prompt if needed (e.g., verbal model). Procedures were identical to those described in the IT section of this table, with the exception of the number of trials per day. Participants had multiple opportunities per day to display the target behavior, which included practice trials with the same target. Procedures were identical to those described in the IT section, with the exception of the format of sessions. When using DTT, adults conducted 10 massed trials per day. A procedure where adults embed opportunities to communicate during typical activities and, based on the child s need, use one of four behavioral interventions to promote expressive language: (a) verbal model of the target behavior, (b) mandmodel procedure where an adult controls opportunities to use language (e.g., interrupt play and provide a non yes or no question), (c) time delay presentation of a stimulus and a specific delay for an independent response (adult provides a verbal model if there is an incorrect response or no response), (d) incidental teaching. A conversational approach to language intervention originally designed to promote positive interactions between a parent and child. Parents join in play and imitate non-verbal object and motor behaviors and provide contingent responses to child vocalizations. Activities are child led and parents promote turn-taking in conversation and play. Parents provide verbal models of target language but do not prompt expressive language. A combination of procedures commonly ascribed to MT and the RII. A child-directed naturalistic intervention that integrates environmental arrangement, responsive interaction strategies, and a hierarchy of milieu teaching interventions (i.e., model [e.g., Say target or target only], mand-model, time delay) to promote expressive language in young children with various exceptionalities (Hemmeter & Kaiser, 1994). A multi-component, parent-implemented intervention that involves training parents to use strategies designed to encourage reciprocal interactions and teach the meanings of words to young children with ASD (Venker et al., 2012). PRT is a multi-component naturalistic intervention and an extension of the NLP. PRT targets pivotal behaviors considered fundamental to development, such as motivation responding to multiple cues, self-management, and initiating interactions. The rationale for targeting pivotal behaviors is that therapeutic changes in pivotal behaviors increase the likelihood of improvement in non-target behaviors. Note. ASD = autism spectrum disorder; NLP = natural language paradigm; PRT = pivotal response training; MTW = Hanen more than words; EMT = enhanced milieu teaching; RII = responsive interaction intervention; MT = milieu teaching; DTT = discrete trial teaching; MITS = modified incidental teaching; IT = incidental teaching. participants made errors, adults typically repeated the full verbal model 1 to 3 times. Following any spontaneous or imitated response, adults typically provided praise plus the related item. If a child never verbalized, the adult did not provide the preferred item and presented another item (assuming lost interest) or attempted again with the same item.

7 Lane et al. 55 Figure 1. Analysis of reported components in each study. Strategies to promote motivation to verbalize. To increase the likelihood participants would continue to attempt to use target verbalizations during intervention sessions, adults interspersed opportunities for the child to request items using known verbalizations and provided opportunities to request a variety of preferred items. Dosage. The number of planned opportunities (or trials) to evoke spontaneous verbalizations, as well as the length and frequency of sessions, varied greatly across all interventions. Sessions typically occurred 2 to 3 times per week for 10 to 15 min. Multiple articles reported that adults embedded one to three opportunities per minute for children to initiate or verbalize during a session (see Table 2). Experimental design. Across the 24 studies in this review, 23 were single-case designs and one was a pre-and post-test randomized controlled trial (see Table 4). Of the single-case designs, 16 were demonstration designs (e.g., withdrawal design, multiple-baseline design), six were comparison designs

8 Table 4. Evaluation of Studies Using What Works Clearinghouse Guidelines. Single-case designs First author (design) Systematic manipulation of NLI IOA collected 20% of sessions IOA at or above 80% 3+ Attempted demonstrations of effect 5 Data points per condition 3 Data points per condition Classification of design standards Classification of evidence for effectiveness a Demonstration Charlop-Christy, (withdrawal) Charlop-Christy, (withdrawal) Charlop-Christy, (withdrawal) Christensen-Sandfort, (MB-P) MDS-R Strong Christensen-Sandfort, (MB-P) MDS-R Strong Gillett, 2007 (non-concurrent MB-P) Hemmeter, 1994 (MB-P) Ingersoll, (ABACAD) Ingersoll, (ABACAD) Ingersoll, (ABACAD) Ingersoll, (ABACAD) Ingersoll, (ABACAD) Koegel, 1987 (MB-P) Koegel, 1998 (MB-P) MDS-R Strong Koegel, 2010 (MB-P) MDS Strong Schreibman, (MB-P) MDS None Schreibman, (MB-P) MDS None Comparison Ingersoll, (ATD) MDS No Ingersoll, (ATD) MDS Yes Ingersoll, (ATD) MDS Yes Ingersoll, (ATD) MDS No Ingersoll, (ATD) MDS Yes Ingersoll, (ATD) MDS No Group design First author (design) Groups randomized Overall attrition Differential attrition Baseline equivalence Minimum reliability No identified confounds Venker, 2012 (randomized pre/post) Note. NLI = naturalistic language intervention; IOA = interobserver agreement; = yes; = no; MB-P = multiple-baseline across participants; MDS-R = meets design standards with reservations; ABACAD = withdrawal design; MDS = meets design standards. a Ingersoll (2010) = alternating treatments designs (ATD); comparisons: differentiated (yes or no). 56

9 Lane et al. 57 (alternating treatments design), and one was a non-concurrent multiple-baseline design (Gillett & LeBlanc, 2007). A nonconcurrent multiple-baseline design does not allow for assessment of a functional relation, essentially functioning as a series of stacked A-B designs (Gast & Ledford, 2014). Analysis of Interventions WWC design standards. Nine single-case designs met design standards without reservations, three met design standards with reservations, and 11 did not meet design standards. All 11 studies that did not meet design standards included fewer than three opportunities to demonstrate the effectiveness of the intervention. Also, eight of these studies included fewer than 3 data points in at least one condition; one study collected IOA less than 20% of sessions and mean IOA was less than 80%. Seventeen of 23 single-case studies used a demonstration design to assess the independent variable, while six used comparison designs. All failures to meet design standards occurred in studies using a demonstration design. One group design study was identified in this review (Venker et al., 2012); the study did not meet design standards due to lack of equivalence across comparison groups during preintervention conditions (see Table 4). WWC evidence of effectiveness. The 12 studies meeting design standards without or with reservations were further evaluated for evidence of effectiveness. Four demonstration studies were classified as having strong evidence of effectiveness (Christensen-Sandfort & Whinnery, 2013; L. K. Koegel, Camarata, Valdez-Menchaca, & Koegel, 1998; L. K. Koegel, Koegel, Green-Hopkins, & Barnes, 2010), while two were not (Schreibman, Stahmer, Barlett, & Dufek, 2009). The four effective studies used MT (Christensen- Sandfort & Whinnery, 2013) and PRT (L. K. Koegel et al., 1998; L. K. Koegel et al., 2010) to increase spontaneous verbalizations in young children with ASD. It is worth noting that in Schreibman et al. (2009), increases in spontaneous verbalizations were observed for two participants in the first study and one participant in the second study, but the effects were not replicated across participants, limiting the utility of results. Regarding the comparison designs, MT, RII, or a combination of these procedures were compared in six studies in one article. Although not possible to demonstrate the effectiveness of the interventions due to lack of a baseline condition, three of six studies showed differentiation between interventions (MT and a combination of both interventions were superior to the RII alone; see Table 4). Procedural fidelity. Fidelity data were limited to 20 studies, where researchers collected treatment fidelity only (i.e., information regarding implementation of the treatment specifically). None of the studies collected procedural fidelity (i.e., procedures used across all experimental conditions were carried out as intended; Wolery, Dunlap, & Ledford, 2011). Seventeen studies did not report the frequency with which treatment fidelity data were collected, and 13 did not report whether fidelity data were at acceptable levels (80% or higher; see Table 2). Summary of Effectiveness Considering WWC Findings Across 24 studies included in 11 articles, 10 naturalistic language interventions were evaluated to assess the effectiveness of the interventions for increasing spontaneous verbalizations. Twelve studies met design standards without or with reservations; those studies are further evaluated below. Two interventions in four demonstration studies were effective in increasing spontaneous verbalizations using MT or PRT for nine young children with ASD who were 3 to 5 years of age. Six alternating treatment designs were used to compare three interventions, MT, RII, and a combination of these interventions (Ingersoll, 2010). Differentiated data were evident when the combined intervention was compared with other interventions. Due to mixed findings, the utility of these comparisons is limited. Also, the lack of methodological rigor in the many studies precluded further assessment of a functional relation. Participant characteristics. Teacher-implemented MT was effective for increasing one form of requesting in three children, 4 to 5 years of age, who were classified as having moderate to severe ASD and displayed limited or no spontaneous verbalizations prior to beginning the study. PRT, implemented by researchers, was effective when increasing one form of asking a question in six children, 3 to 5 years of age, who used (n = 3) or displayed limited use of (n = 3) spontaneous verbalizations. Data reported for two studies in Schreibman et al. (2009) produced mixed results when PRT was introduced, with some change in multiple forms of spontaneous verbalizations from baseline to intervention for half (n = 3; 2 4 years of age) of the participants; recommendations are limited as a functional relation could not be demonstrated. Given the relatively small sample of participants, preintervention behaviors are limited to understanding that all participants displayed delayed expressive communication or cognitive scores, but results were mixed when considering use of spontaneous verbalizations, ranging from no spontaneous verbalizations to typical use of some spontaneous verbalizations. Components of effective interventions. Strategies to promote engagement during intervention sessions align with best practice recommendations for early childhood education and early childhood special education (DEC of the Council

10 58 The Journal of Special Education 50(1) for Exceptional Children, 2014; National Association for the Education of Young Children, 2009) and, as such, these strategies were not analyzed by effective versus ineffective interventions, with consideration of methodological rigor. In addition, strategies to promote motivation during sessions were likewise not analyzed separately. In regard to setting up opportunities to evoke spontaneous verbalizations, all effective studies used environmental arrangement strategies (e.g., place desired toys/objects in clear plastic containers or high on shelves) to begin an opportunity (or trial) to verbalize. When using adult prompts to promote spontaneous verbalizations, the following components were used in effective studies: When beginning an intervention or when targeting novel words or phrases, adults immediately presented a full verbal model of the target word or phrase, also known as 0-s prompt delay. After using a 0-s prompt delay, in subsequent sessions, adults began using a mand-model prompt followed by transitioning to a time delay procedure (waiting at least 5 s for a spontaneous verbalization). Following a spontaneous or imitated response, adults provided praise or the related item to the participant at the end of the opportunity (or trial) to verbalize. These components are not meant to negate the procedures of other studies included in this review or other naturalistic language interventions in the literature, but to more so highlight studies that targeted increasing spontaneous verbalizations only (excluding other behaviors; for example, eye contact or orientation) in young children with ASD during typical activities. Stringent methodological rigor guidelines were used to identify procedures that we currently have confidence demonstrated a functional relation when targeting this behavior under specific conditions with young children with ASD. Although other studies displayed positive effects for participants, they lacked the appropriate rigor, thus decreasing the confidence in reported findings; definitive recommendations using these procedures could not confidently be made. Discussion The purpose of this review was to identify effective naturalistic language interventions for promoting spontaneous expressive language (defined in the current review as occurring in the absence of a prompt or other verbalization from an adult or peer) in young children with ASD. Ten naturalistic interventions were identified in 24 studies in 11 articles (single-case studies = 23; group design study = 1); MT (alone or combined with RII) was the most commonly evaluated intervention. Most participants were 2 to 5 years of age (range = 2 9 years) and displayed delays in expressive communication or delays across domains. Participants ranged from those who did not use spontaneous verbalizations to those who used some spontaneous verbalizations to communicate wants and interests. Other descriptors, such as severity of diagnosis and play skills, were less likely to be reported. Intervention sessions were typically conducted in a clinic and, to a lesser extent, homes and schools. Trained parents or teachers were more likely to implement interventions than researchers, with the majority of studies targeting multiple forms (e.g., adjective noun or noun verb combinations) of expressive communication within a single session. WWC guidelines were used to evaluate methodological rigor, followed by evaluation of data for studies meeting guidelines without or with reservations. Based on the results of this review, half of the studies (6 = demonstration designs; 6 = comparison designs) met adequate rigor requirements. Six of those studies had adequate rigor and demonstrated a robust change in spontaneous verbalizations. Thus, when increasing spontaneous verbalizations in children with ASD who display delays in expressive communication, there is increased confidence that MT or PRT will lead to a meaningful change in the target behavior. Implications for Practice Young children with ASD are less likely than their peers with typical social development to initiate interactions, including using functional verbalizations to communicate wants and interests (Zager et al., 2012). Current recommendations for young children, including those with ASD, indicate the need for providing services in a play-based format in typical settings using age-appropriate materials during play (DEC of the Council for Exceptional Children, 2014; Wolery & Hemmeter, 2011). In this review, the components of each intervention were analyzed, coded, and grouped by four distinct functions, including (a) promoting engagement, (b) creating opportunities for spontaneous verbalizations, (c) using adult prompts to encourage verbalizations, and (d) maintaining a child s motivation to verbalize throughout a session. Promoting engagement, as well as maintaining a child s motivation to verbalize, aligns with recommendations for best practice. Thus, teachers and practitioners are encouraged to implement interventions or train parents to conduct sessions in typical settings. In addition, adults should follow a child s lead with a focus on promoting social (early conversation) and motoric (e.g., sharing, waiting) turn-taking, as well as describe a child s play, model age-appropriate verbalizations and actions on materials, and expand all verbalizations (for all identified adult behaviors, see Figure 1). When setting up and prompting spontaneous verbalizations, a number of components were identified. Identified components were coded from several interventions shown to be effective with a variety of children with various diagnoses in the literature. For purposes of this review, recommendations are conservative, meaning recommended components

11 Lane et al. 59 are limited to naturalistic interventions that had adequate rigor and were effective across participants; thus, there is increased confidence in these components. When attempting to promote and prompt spontaneous verbalizations during initial intervention sessions, teachers and practitioners should consider an environmental arrangement strategy followed by a 0-s prompt delay (full verbal model of the target verbalization). Whether prompted or unprompted, adults should provide praise and reinforcement in the form of providing a desired item. In subsequent sessions, adults should provide less intrusive support in the form of a mand-model procedure followed by a naturalistic time delay. These recommendations include components of many commonly prescribed naturalistic language interventions in the literature; however, recommendations are limited to studies that met the stringent criteria of this review. Implications for Research Naturalistic language interventions represent a vast collection of studies for increasing social-communication skills in typical settings or clinics designed to parallel these settings (Kaiser & Grim, 2005; Schreibman et al., 2015). Under the umbrella of social-communication skills is the need to increase functional spontaneous expressive language in young children with ASD, especially children who are transitioning from prelinguistic communication to using spoken words or those who only use a few novel words. In this review, a relatively small number of studies (N = 24) directly targeted increasing spontaneous expressive language alone in young children with ASD (N = 45), and within these studies, half lacked adequate rigor to reliably evaluate the results. The most common issue was using an inadequate experimental design to evaluate an intervention (e.g., multiple-baseline design across two participants instead of three), along with collecting less than 3 data points in the baseline condition, thus precluding evaluation of a clear pattern of responding before introducing an intervention. Also, researchers typically did not collect fidelity data, with no studies assessing procedural fidelity. Lack of fidelity data further limits the utility of findings as there is no way to determine if the prescribed components were implemented as planned; this is especially important for studies that involve training parents or teachers to implement interventions. Researchers should evaluate these interventions using adequate rigor (use an appropriate experimental design, collect at least 3 data points in the baseline and intervention condition, assess fidelity of implementation of all prescribed variables) allowing for a more reliable evaluation of findings. Once more, rigorous experimental studies are conducted; researchers should then evaluate the components of interventions to identify active components necessary to lead to increases in spontaneous verbalizations. Finally, researchers should provide clear, detailed descriptions of participants preintervention behaviors to understand with whom interventions are most likely to be effective. The results of this review also expand on the current definition of naturalistic language provided by Schreibman et al. (2015), as well as other researchers such as Kaiser and Trent (2007) and Charlop-Christy, LeBlanc, and Carpenter (1999), by further characterizing specific components of naturalistic language interventions specifically designed to increase spontaneous expressive language independently in young children with ASD. Although the results of this review do not encompass every aspect of naturalistic language interventions, they do provide a more definite description of components under certain conditions for young children with ASD. Kaiser and Trent state the need for explicit identification of components of naturalistic language interventions as a way of increasing the precision of service delivery for young children. In addition, Charlop- Christy and colleagues (1999) evaluated previously published studies on naturalistic language intervention, specifically analyzing three naturalistic interventions. In this review, we analyzed 10 named interventions in 24 studies further increasing the field s understanding of specific components of naturalistic language interventions. Limitations Limitations of this review warrant attention. First, all keywords were paired with autis* when searching for articles. More articles may have been included if keywords were paired with pervasive developmental disorder. In addition, the inclusion and exclusion criteria for the literature search resulted in a small number of studies available for review. Although this is a possible limitation, the authors felt that the specificity of the criteria was important for a rigorous evaluation of naturalistic language interventions in this population of young children, given the desire of parents that their young children begin to or more readily communicate. Finally, fidelity data were assessed across all articles, but implementation of fidelity in studies that included parent or teacher training was not evaluated separately, which was outside of the scope of this review. Concluding Remarks This review identified and grouped several common components of naturalistic language interventions for young children with ASD in a small sample of methodologically rigorous studies. It is important to stress that the findings of this review do not necessarily indicate that a person could simply use all identified characteristics and expect the same results. Moving forward, future studies should consider evaluating these characteristics, identifying active components for success. Critical evaluation of interventions aligns with the principle of parsimony (Wolery, Ault, & Doyle, 1992) when providing services

12 60 The Journal of Special Education 50(1) to children with ASD using the most simple but effective intervention that promotes long-term success. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article. References *Indicates articles included in the review. *Charlop-Christy, M. H., & Carpenter, M. H. (2000). Modified incidental teaching sessions: A procedure for parents to increase spontaneous speech in their children with autism. Journal of Positive Behavior Interventions, 2, Charlop-Christy, M. H., & Jones, C. (2006). The Picture Exchange Communication System: Nonverbal communication program for children with autism spectrum disorders. In R. J. McCauley & M. E. Fey (Eds.), Treatment of language disorders in children (pp ). Baltimore, MD: Paul H. 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