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LSHSS

Research Article

Explicit Grammar Intervention in Young School-Aged Children With Developmental

Language Disorder: An Efficacy Study Using Single-Case Experimental Design

Samuel D. Calder,a Mary Claessen,a Susan Ebbels,b,c and Suze Leitãoa

Purpose: This study evaluated the efficacy of an explicit, combined metalinguistic training and grammar facilitation intervention aimed at improving regular past tense marking for nine children aged 5;10–6;8 (years;months) with developmental language disorder. Method: This study used an ABA across-participant multiple-baseline single-case experimental design. Participants were seen one-on-one twice a week for 20- to 30-min sessions for 10 weeks and received explicit grammar intervention combining metalinguistic training using the SHAPE CODING system with grammar facilitation techniques (a systematic cueing hierarchy). In each session, 50 trials to produce the target form were completed, resulting in a total of 1,000 trials over 20 individual therapy sessions. Repeated measures of morphosyntax were collected using probes, including trained past tense verbs, untrained past tense verbs, third-person singular verbs as an extension probe, and possessive ’s as a control probe. Probing contexts included expressive morphosyntax and grammaticality judgment. Outcome measures also

included pre–poststandard measures of expressive and receptive grammar. Results: Analyses of repeated measures demonstrated significant improvement in past tense production on trained verbs (eight of nine children) and untrained verbs (seven of nine children), indicating efficacy of the treatment. These gains were maintained for 5 weeks. The majority of children made significant improvement on standardized measures of expressive grammar (eight of nine children). Only five of nine children improved on grammaticality judgment or receptive measures. Conclusion: Results continue to support the efficacy of explicit grammar interventions to improve past tense marking in early school-aged children. Future research should aim to evaluate the efficacy of similar interventions with group comparison studies and determine whether explicit grammar interventions can improve other aspects of grammatical difficulty for early school-aged children with developmental language disorder. Supplemental Material: https://doi.org/10.23641/asha. 11958771

D evelopmental language disorder (DLD) refers to a condition in which children experience lan- guage difficulties in the absence of known bio-

medical conditions or acquired brain injury (Bishop,

Snowling, Thompson, Greenhalgh, & CATALISE-2 Con- sortium, 2017). Compared to typically developing peers, children with DLD present with particular difficulties in morphosyntactic skills, such as the use (Rice, Wexler, & Hershberger, 1998) and judgment (Rice, Wexler, & Redmond, 1999) of grammatical morphemes associated with tense.

Finiteness marking is challenging for children with DLD (see Leonard, 2014, for a review). Finiteness refers to the obligatory marking of verbs indicating subject–verb agreement and tense, including affixation of morphemes –ed (e.g., the girl walked) and –s (e.g., the girl walks) to verbs for past and present tenses, respectively. Within English and cross-linguistically, finiteness is a quality of well-constructed clauses (Dale, Rice, Rimfeld, & Hayiou-Thomas, 2018). There is evidence supporting disordered finiteness as a distinct etiological construct and predictive marker of lan- guage growth for DLD (Bishop, Adams, & Norbury, 2006).

aSchool of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, Western Australia bMoor House Research and Training Institute, Moor House School & College, Oxted, United Kingdom cLanguage and Cognition, University College London, United Kingdom

Correspondence to Samuel D. Calder: [email protected]

Editor-in-Chief: Holly L. Storkel Editor: Amanda J. Owen Van Horne

Received March 19, 2019 Revision received July 1, 2019 Accepted October 5, 2019 https://doi.org/10.1044/2019_LSHSS-19-00060 Publisher Note: This article is part of the Forum: Morphosyntax Assessment and Intervention for Children.

Disclosure: The authors have declared that no competing interests existed at the time of publication.

Language, Speech, and Hearing Services in Schools • Vol. 51 • 298–316 • April 2020 • Copyright © 2020 American Speech-Language-Hearing Association298

Children’s grammar difficulties are a primary source of pa- rental concern when considering referral for clinical services (Bishop & Hayiou-Thomas, 2008).

Grammar Interventions Treatment for DLD aims to accelerate language growth

and remove barriers to functional communication by har- nessing strengths (Justice, Logan, Jiang, & Schmitt, 2017). Ebbels’s (2014) review indicates an emerging evidence base for the effectiveness of grammar intervention for school- aged children with DLD. Current evidence is parsed into implicit and explicit approaches to intervention. According to Ebbels’s framework, implicit interventions target production and understanding of grammar using grammar facilitation techniques implicitly by responding to children’s errors in a naturalistic way (Fey, Long, & Finestack, 2003). Children’s learning and the knowledge acquired are not necessarily associated with awareness. Explicit interventions target in- creased awareness of the goals of intervention with a pre- established concept of the criteria for success: Learning is conscious and deliberate, and information can be recalled on demand (Shanks, 2005). Within each approach to inter- vention, specific techniques are used to improve acquisition of grammar.

Implicit Interventions Using Grammar Facilitation Intervention and scaffolding techniques used in im-

plicit approaches are described as grammar facilitation (e.g., Fey et al., 2003), which aims to facilitate the acquisition of grammar by increasing the frequency and quality of target forms in input and output. Greater exposure to and oppor- tunities to learn and use language theoretically accelerates the likelihood of language growth (Leonard, 2014). Studies have empirically tested grammar facilitation techniques sup- porting their use with expressive morphosyntax targets, including imitation (Nelson, Camarata, Welsh, Butkovsky, & Camarata, 1996), modeling (Weismer & Murray-Branch, 1989), focused stimulation (Leonard, Camarata, Brown, & Camarata, 2004), and conversational recasting (see Cleave, Becker, Curran, Van Horne, & Fey, 2015, for a review). Recently, Van Horne, Fey, and Curran (2017) reported on a primarily implicit intervention, in which procedures in- cluded a combination of sentence imitation, observational modelling, storytelling and focused stimulation, recasting, and cueing for incorrect responses. All eighteen 4- to 10-year- old children with DLD enrolled in the study improved their use of regular past tense. Notably, as participants were dismissed from the study following 36 sessions, many still did not achieve mastery of the intervention target. In general, outcomes following implicit intervention are favor- able for morphosyntax in preschool-aged children (Leonard, 2014); however, mastery of intervention targets is rarely reported.

Explicit Intervention Using Metalinguistic Training Difficulties with morphosyntax often persist into

school age for children with DLD (Bishop, Bright, James,

Bishop, & Van der Lely, 2000). An alternative approach may be required because children with DLD may have difficulty learning grammar through implicit grammar fa- cilitation. Metalinguistic training aims to improve children’s learning of the rules of grammar by creating conscious awareness of grammar through explicit metacognitive teach- ing (Ebbels, 2014), allowing children to actively reflect on language targets. Meta-awareness is enhanced, so rules of grammar are learned explicitly in a compensatory way.

Metalinguistic techniques can be used explicitly to teach grammar through metacognitive strategies using visual supports and graphic organizers (Ebbels, 2014). The SHAPE CODING system is designed to explicitly teach oral and written syntax to children with language disorder (Ebbels, 2007). Ebbels, van der Lely, and Dockrell (2007) compared use of the SHAPE CODING system with semantic therapy and a no-treatment control group with 27 children with DLD aged between 10 years and 16;1 (years;months). The authors concluded that the SHAPE CODING system is a viable and efficacious treatment approach to improve verb argument structure in older school-aged children. Although evidence for improvement in grammar comprehension is mixed (e.g., Zwitserlood, Wijnen, van Weerdenburg, & Verhoeven, 2015), children may be able to consciously re- flect upon the rules of grammar through explicit interven- tions in the presence of receptive language difficulties to improve understanding, especially older children (Ebbels, Marić, Murphy, & Turner, 2014).

Grammar intervention approaches effective for chil- dren above 8 years old should be tested with younger chil- dren to address the concerning gap in evidence for this age group (Ebbels, 2014). Furthermore, Ebbels (2014) suggested there may be benefit to integrating therapy techniques to include grammar facilitation and metalinguistic training in a range of activities (e.g., Fey et al., 2003). Combined ap- proaches are yet to be explored extensively.

Combined Intervention Approaches In an early-stage efficacy study, Finestack (2018)

used a combined implicit/explicit metalinguistic approach compared to an implicit approach to teach novel morphemes to 6- to 8-year-old children with DLD. The combined ap- proach was more efficacious than the implicit approach, with gains being maintained and generalized. In a random- ized controlled trial of 31 preschool-aged children, Smith- Lock, Leitão, Prior, and Nickels (2015) used explicit teaching principles combined with a systematic cueing hierarchy, which was effective in improving use of expressive morpho- syntax when compared to conversational recasting alone. Importantly, the study included a metalinguistic component where children in the explicit group were aware of the thera- peutic goal (Smith-Lock et al., 2015). Kulkarni, Pring, and Ebbels (2013) conducted a clinical evaluation of the SHAPE CODING system combined with elicited production and recasting to improve the use of past tense for two children with DLD aged 8;11 and 9;4. Both made significant gains in their use of the target structure.

Calder et al.: Grammar Intervention in Young Children With DLD 299

Although grammar facilitation is generally considered implicit (Ebbels, 2014; Fey et al., 2003), there is evidence that the techniques can be used explicitly. In a pilot efficacy study, Calder, Claessen, and Leitão (2018) combined the SHAPE CODING system with the systematic cueing hier- archy detailed in Smith-Lock et al. (2015) to improve gram- mar in three children with DLD aged 7 years. Importantly, systematic cueing as a grammar facilitation technique in this study was explicit. Cues ranged from least to most sup- port, and there was a focus on teaching correct production of grammar through errors to avoid the child perceiving the error to be semantic in nature, as may be the case when using conversational recasting without stating the goal of intervention first. The findings provided early evidence supporting the use of combined intervention approaches to improve receptive and expressive grammar, particularly production of regular past tense following 5 weeks of inter- vention. Notably, participants made gains in expressive grammar following only 10 intervention sessions across 5 weeks, which is markedly shorter duration than reported in many intervention studies. However, the authors ac- knowledge that including measures of teaching, maintenance, and generalization (e.g., Finestack, 2018) would have broad- ened understanding of treatment effects and that a longer period of intervention might be necessary.

Grammar Interventions in Clinical Practice Recently, Finestack and Satterlund (2018) reported

on a national survey of speech-language pathology practice in the United States. Past tense verb production was a common intervention goal for practitioners in both early (40%) and elementary education settings (60%). Interest- ingly, overall between 60% and 70% used explicit presenta- tions as an intervention procedure, despite relatively little investigation in this area until recently. Therefore, it appears explicit instruction to improve past tense may not only be supported by an emerging evidence base but is also fre- quently used in clinical practice.

The Current Study For early school-aged children, preliminary data sug-

gest that explicit, combined metalinguistic and grammar facilitation approaches are efficacious in treating the use of tense marking and for improving receptive grammar more generally (Calder et al., 2018). Building on early-stage studies of treatment efficacy is required to determine if treat- ment procedures are considered evidence based. Fey and Finestack (2008) outline the need for a programmatic ap- proach to pursuing intervention research, specifically noting the value of small-scale studies aimed at exploring and identifying specific components of intervention approaches and their effects on specific populations. This study forms a part of a program of research to design, develop, and evaluate the efficacy of an explicit, combined grammar in- tervention in line with Robey’s phases of clinical research (Robey, 2004). We report on a range of measures to evaluate the efficacy of explicit intervention to improve grammar.

Single-case experimental design (SCED) methodology was used to test the following confirmatory hypotheses and is reported as per the Single-Case Reporting guideline In BEhavioural interventions (Tate et al., 2016):

1. For young school-aged children with DLD (specifically aged 5;10–6;8), there will be a significant treatment effect on trained past tense verbs and a generalized effect to untrained verbs across 20 sessions of explicit intervention combining metalinguistic and grammar facilitation techniques.

2. These children will improve significantly on pre– poststandardized measures of expressive and receptive grammar.

Method Research Design Design

The current study was an ABA across-participant multiple-baseline SCED, including a minimum of five data points (i.e., sessions) for each phase (Kratochwill et al., 2012). Multiple baselines were conducted for varied dura- tions across participants, and introduction of treatment to participants was staggered. Repeated measures were col- lected throughout the intervention phase and posttreatment maintenance phase (Dallery & Raiff, 2014), including the target behavior (past tense verbs), an extension of the tar- geted behavior (third-person singular [3S] verbs), and a control behavior (possessive ’s). This design is noted for robustness regarding strengths of internal validity and exter- nal validity when compared to other SCEDs (Tate et al., 2016). As a Phase I–II study, we replicated and built on findings from Calder et al. (2018) by refining intervention protocols, determining optimal dosage, and evaluating du- ration of therapeutic effect (Robey, 2004).

Randomization To improve internal validity further, participants

were randomly assigned to one of three predetermined staggered onset to intervention conditions. To ensure con- cealed allocation, participants were assigned a code that was entered into a random list generator by a blinded re- searcher. Participants received five (P1, P3, P8), seven (P5, P7, P9), or nine (P2, P4, P9) pre-intervention baseline sessions over as many weeks; 20 intervention sessions over 10 weeks; and five postintervention sessions to evaluate maintenance. Participants were also randomized to gram- maticality conditions described below.

Blinding Participant caregivers and teachers were aware chil-

dren were receiving grammar intervention but were blinded to the intervention target. Postintervention measures were collected via blinded assessment using trained student speech- language pathologists (SLPs).

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Participants Selection Criteria

Participants included nine early school-aged children diagnosed with DLD. The inclusion criteria were aged between 5;6 and 7;6, English as a primary language, and grammar difficulties associated with DLD. Exclusionary criteria included a neurological diagnosis, a cognitive im- pairment, and hearing outside normal limits. Participants were recruited from a specialized educational program for students diagnosed with DLD. Ethical approval for the study was obtained from the Curtin University Human Research Ethics Committee (approval number: HRE2017- 0835) and the Western Australian Department of Educa- tion. The principal consented school participation and then provided information letters and consent forms to the parents/carers of potential participants identified by SLPs and teachers employed at the educational program. Parents returned the completed consent forms if they wished their child to participate. The study reached capacity at nine participants so we could achieve three replications over three baseline conditions as per reporting standards (Kratochwill et al., 2012).

Participant Characteristics The participants’ school enrolment package was

accessed, including the assessment protocol and the most recent standardized assessment scores available. Data in- cluded Clinical Evaluation of Language Fundamentals Preschool–Second Edition (Wiig, Secord, & Semel, 2004), a test of nonverbal IQ, and a comprehensive exploration of previous medical history to identify contributing factors to language difficulties, such as acquired neurological dam- age, or hearing loss. These factors combined are consid- ered evidence of a diagnosis for DLD (Bishop, Snowling, Thompson, Greenhalgh, & CATALISE Consortium, 2016). Participants then passed a hearing acuity test. All partici- pants passed the Phonological Probe from the Test of Early Grammatical Impairment (Rice & Wexler, 2001) for artic- ulation of phonemes necessary for morphosyntactic pro- duction targets.

All demographic information is presented in Table 1. Participants included eight boys and one girl aged between 5;10 and 6;8 at initial assessment. Ages at enrolment to

the specialist school varied from 3;8 to 5;11. P1, P2, P4, and P8 were in their third year of placement at the school; P3, P5, P7, and P9 were in their second; and P6 was in her first.

Measures Repeated Measures

Repeated measures of morphosyntax were collected at every data point using various probes, including trained probes, untrained probes, an extension probe, and a control probe (elaborated in the following sections). Probing con- texts included both expressive morphosyntax and grammati- cality judgment. Grammaticality judgment was selected as a method of measuring grammatical progress, as there is evidence performance on such tasks mirrors production tasks (Rice et al., 1998, 1999). As grammaticality judgment is a clinical marker of DLD (Dale et al., 2018; Rice et al., 1999), identification of grammatically correct sentences in the studied participants was expected to be below chance levels of accuracy prior to intervention.

Trained probes. Regular past tense (–ed) repeated measures of trained verbs were probed in two conditions: 12 –ed verbs trained within sessions were measured, and 12 –ed verbs from the previous session were measured. All –ed verbs were predetermined at the outset of intervention and selected based on their suitability to intervention activi- ties. We also chose verbs that were not in the Grammar Elicitation Test (GET; described below; Smith-Lock, Leitão, Lambert, & Nickels, 2013) to allow comparison between trained and untrained verbs. These probes were adminis- tered during the intervention phase at the end of Session 2 (i.e., data point B1 the first week of intervention) and every even session thereafter.

Untrained probes. Repeated measures of untrained expressive morphosyntax probes were selected from an adapted version of the GET. This experimental test was designed to elicit multiple instances of specific expressive morphosyntax targets, including 30 items probing the treated grammatical structure (–ed). Repeated measures were also developed for a grammaticality judgment task including 30 –ed probes. Videos of actions depicting the declarative clauses containing –ed were created as stimuli for untrained probes. Accompanying audio for each task item, both

Table 1. Demographic information.

Participant ID Sex Age at enrolment to school

(years;months) Current year at specialized

educational program Age at initial assessment for study (years;months)

P1 Male 4;0 3rd 6;3 P2 Male 3;11 3rd 6;2 P3 Male 4;7 2nd 5;10 P4 Male 5;4 3rd 6;8 P5 Male 5;2 2nd 6;6 P6 Female 5;11 1st 6;2 P7 Male 5;3 2nd 6;7 P8 Male 3;8 3rd 6;0 P9 Male 4;9 2nd 6;1

Calder et al.: Grammar Intervention in Young Children With DLD 301

grammatical and ungrammatical (e.g., The girl painted a picture. vs. The girl paint* a picture.), was recorded by a woman with an Australian accent, blinded to the purpose of the research. Each video with corresponding audio was embedded into a Microsoft PowerPoint presentation. Participants wore Sony noise-cancelling headphones during administration and were required to decide if the sentence “sounded right” by pressing “yes” or “no” on a tablet app. Items were counterbalanced for grammaticality, so partici- pants did not receive the same combination of grammatical/ ungrammatical items, and there was no pattern in the pre- sentation of grammatical/ungrammatical items to counter- act a priming effect.

Complete sets of 30 untrained –ed verbs were probed pre- and postintervention. Sets were randomized for ad- ministration at the initial assessment (Timepoint 1), 1 week prior to intervention commencing (Timepoint 2), 1 week following intervention (Timepoint 3), and 5 weeks following cessation of intervention (Timepoint 4). Both expression and grammaticality judgment were assessed.

Reduced randomized sets were generated for each other data point using nine expressive probes and 12 gram- maticality judgment probes. All possible allomorphs were included (i.e., [d], [t], and [əd]) and equally distributed. Probes were administered via laptop during the pre-intervention baseline phase, at the beginning of Session 3 (i.e., data point B2 in the second week of intervention) and every odd ses- sion thereafter during the intervention phase, and in the postintervention maintenance phase.

Extension probes. Expressive repeated measures of 3S served as an extension of the treated structure. Items in- cluded 30 probes and were taken from the GET. A gram- maticality judgment task was also developed as per the untrained –ed probes (e.g., The man sneezes. vs. The man sneeze*.). 3S was considered an extension measure due to the structure’s relative complexity compared to –ed, since bare stem forms are grammatical when used with first- person subject pronouns or plural subject nouns (e.g., I like ice cream vs. The boys like ice cream vs. The boy likes ice cream). We also expected there might be improvement in 3S due to the frequent instances of input during therapy (see Intervention section) and increased awareness of the need for tense marking.

Control probes. Similarly, expressive repeated measures of possessive ’s served as a control probe. Items included 30 probes and were taken from the GET. As above, a grammaticality judgment task was developed (e.g., The spider is living on a leaf. This is the spider’s leaf. vs. The spi- der is living on a leaf. This is the spider* leaf.). For ’s, still images of nouns depicting ownership were retrieved from copyright-free image sources. ’s was considered a control as this noun possession was not taught as part of therapy and therefore should remain stable throughout the inter- vention period.

For extension and control probes, all possible allo- morphs were included (i.e., [s], [z], [əz]) and equally distributed. Randomized sets of nine expressive and 12 grammaticality judgment items were generated and administered as per the

untrained –ed probes during pre-intervention, intervention, and postintervention phases.

Pre–Post The Structured Photographic Expressive Language

Test–Third Edition (SPELT-3; Dawson, Stout, & Eyer, 2003) and the Test of Reception of Grammar Version 2 (TROG-2; Bishop, 2003) were administered both pre- and postintervention as expressive and receptive standardized grammar measures, respectively. The SPELT-3 measures expressive morphosyntax using 54 items across a range of structures and was normed on children aged 4–9 years. To address discriminant accuracy of the test, Perona, Plante, and Vance (2005) determined 90% sensitivity and 100% sen- sitivity at 95 cutoff (−0.33 SD). This cutoff score was used for the current study based on the recommendation, al- though it is noted that while other studies applied this cut- off with older children (e.g., Van Horne et al., 2017), Perona et al. (2005) sampled children aged 4–5 years. The TROG-2 measures a total of 20 different grammatical structure con- trasts and was normed on children aged 4–16 years. Dis- criminant accuracy was evaluated on a sample of 30 children aged 6;2–10;11, which confirmed the test is sensitive to identifying communication difficulties in children (Bishop, 2003). Both tests have strong reliability and appropriate validity.

Reliability A blinded researcher scored 20% of all measures au-

dio- and video-recorded throughout the study. Interrater reliability for experimental measures was calculated using intraclass correlation coefficients (ICCs) using absolute agreement and single measures in a two-way mixed-effects model. Interpretation of ICC values is as follows: < .40 = poor, .40–.59 = fair, .60–.74 = good, and .75–1.00 = excel- lent (Cicchetti, 1994). For trained –ed probes, the ICC for expressive measures was .879, and the ICC for grammati- cality judgment was .977. The ICC for expressive un- trained –ed, 3S, and ’s probes was .937, and the ICC for the grammaticality judgment of untrained –ed, 3S, and ’s probes was .985. Therefore, excellent agreement was observed across all experimental measures.

Intervention All intervention sessions were videotaped and carried

out in a quiet space at the site of the educational program. Procedures were similar to those reported by Calder et al. (2018) and are explained within the model suggested by Warren, Fey, and Yoder (2007) for describing treatment intensity. The dose was 50 trials within 20- to 30-min ses- sions; dose form was explicit intervention combining meta- linguistic training using the SHAPE CODING system (Ebbels, 2007) with a systematic cueing hierarchy (Smith- Lock et al., 2015); dose frequency was twice a week, total intervention duration was 10 weeks, and cumulative interven- tion intensity was 50 trials × 2 times per week × 10 weeks, resulting in a total of 1,000 trials over 20 individual

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therapy sessions through roughly 7–10 hr of therapy. This is double the intervention duration in the pilot study (Cal- der et al., 2018), where authors suggested that participants may demonstrate larger treatment effects following a lon- ger duration. Training of morphosyntax was embedded within engaging and naturalistic activities suited to early school-aged children, including playdough, board games, and playing with puppets as well as farm and sea creature manipulatives. Target morphemes were presented in syntactic structures as they occurred felicitously within these activities. The first author (S. D. C.), a trained SLP, delivered all interventions.

Each session began with a short recap of the aims: to say WHAT DOING words (verbs) that have already happened and to add the sounds ([d], [t], [ǝd]) onto the end of those words. Next, the SLP would direct the child’s atten- tion to the laminated shapes and arrows used as a visual organizer throughout session activities. See Figure 1 for es- sential shapes, including the oval (subject noun phrase WHO/ WHAT?), the hexagon (verb phrase WHAT DOING?), and the rectangle (object noun phrase WHO/WHAT?). Additional visual cues included three separate laminated cards that depicted a “left down arrow” to depict –ed and an orthographic representation of the allomorphs (i.e., “d” for [d], “t” for [t], and “ed” for [ǝd]). The SLP said, “Last time, we used our shapes and arrows to help us. Like this: ‘We move our shapes and arrows. What did we do? We moved [bring ‘d’ arrow into the WHAT DOING? hexagon] our shapes and arrows. The [d] at the end of moved lets us know it’s already happened.” The participant was reminded, …