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Treatment Effects on Language Skills Using Discrete Trial Training on a Child With Late Cochlear Implant: A Case Study
*Corresponding author: Prakruthi Venkobarao Jagatap, Center for Speech and Language Disorders in Children, Adults and Senior Citizens, All India Institute of Speech and Hearing, Mansagangothri, Mysore, 570006, Karnataka, India. prakruthijagatap09@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Manjunatha MBV, Jagatap PV, Mukunda Bhagyalakshmi N, Keralapura Mahadevappa A, Sathish L, Agarwal Y, et al. Treatment Effects on Language Skills Using Discrete Trial Training on a Child With Late Cochlear Implant: A Case Study. J Health Allied Sci NU. doi: 10.25259/JHS-2024-11-18-(1670)
Abstract
Discrete trial training (DTT) was used to test its effects on four target grammatical morphemes and its generalisation and maintenance to untrained stimulus exemplars in a child with late cochlear implantation. A 6.9-year-old female child with profound hearing loss who had late cochlear implantation at 5.6 years with no other known sensory and cognitive co-morbidities underwent DTT. Treatment trials using the behavioural principles of DTT were carried out by presenting the target exemplars on a personal laptop in a sequential order using a background animation with and without modelling. Treatment progress was monitored in every session that lasted 45 minutes for a total of 22 sessions. Treatment trials for the four grammatical morphemes showed 100% acquisition within the first 20 trials. The child also showed an ability to generalise the learned grammatical morphemes to untrained exemplars on the probes that followed, to a criterion of 90%. A response accuracy of 90% was also observed for untrained exemplars 20 days post-treatment. DTT can reduce the treatment time for rehabilitating grammatical morphemes in children with hearing impairment. The rate of language development and the observed maintenance imply that DTT is one of the promising approaches to treat language deficits in children with late cochlear implants.
Keywords
Discrete trial training
Generalisation
Language delay
Language learning
Late cochlear implantation
INTRODUCTION
Discrete trial training (DTT) is a structured behavioural intervention method developed by Lovaas.[1,2] This method was initially used to teach specific skills to individuals with autism spectrum disorder and intellectual disability.[1-5] Later studies carried out on other communication disorders, such as language delays, speech sound disorders in hearing impairment, and apraxia of speech[6-8] have yielded promising results.
This procedure involves one-to-one delivery of brief (5-20 seconds), massed practice trials that reinforce correct responses.[9] DTT provides a greater chance at success than conventional methods in training specific behaviours, as the opportunities provided are numerous, thus helping in generalisation.[3] DTT involves three main hierarchies, starting with the base rating of potential target behaviours identified through a detailed speech and language assessment, followed by treatment, and concluding with the measurement of response rates across untrained stimulus sets, a process known as ‘probing.’[10] A speech language pathologist (SLP) learns this therapy procedure within 3-4 sessions.[11]
Children with hearing impairment undergo rehabilitation with hearing aids, cochlear implants (CI), or a combination of both, accompanied by intense listening, speech, and language therapy. Acquiring grammatical morphemes (e.g., plural ‘s’, conjunctions ‘and’, progressive ‘ing’ forms) poses significant challenges for children with hearing impairment, a situation that persists after post-cochlear implantation rehabilitation.[12-14] This difficulty gets compounded when the age of cochlear implantation exceeds 3 years.[13,15]
Several past studies have shown the positive effects of early cochlear implantation on language learning.[13,16-18] Late implantation results in delayed auditory input, depriving the neural circuitries that connect the auditory cortex, thereby impacting language development.[19,20] Early implantation facilitates language development through ‘incidental learning’ where children immersed in ‘natural environments’ pick up the overheard conversations with caregivers and peer group interactions. In contrast, with increasing age, the ability to learn language through incidental learning decreases, necessitating didactic, structured instruction. This is true in cases of late cochlear implants, as the considerable language delay present before implantation necessitates a faster-than-normal rate of language learning.[21] In this context, we suggest that DTT can effectively bridge the language gap and accelerate language development in children who receive late cochlear implants. The learned language can be subsequently integrated into naturalistic contexts to foster generalisation across settings.[16]
To date, no study has investigated the effects of DTT on children who have received late cochlear implants. However, a single study[7] has reported positive outcomes by enhancing the articulatory abilities of three adults with CI. The present study investigated the effects of DTT on a native Hindi-speaking child who received CI at the age of 5.6 years for a few selected grammatical morphemes. The study also presents the generalisation of treatment targets and their maintenance over a short time gap.
CASE REPORT
The procedure of DTT was carried out on a 6.9-year-old female child with congenital hearing loss who underwent cochlear implantation in July 2023 (at 5.6 years of age) with no other known comorbid sensory or cognitive issues. She was using hearing aids prior to the implant and had been attending speech and language therapy and listening therapy since August 2021, for 3 months, and again in August 2022, for 9 months. Listening therapy was resumed after CI (right ear- CI; left ear- hearing aid) in August 2023 and speech & language therapy in May 2024. The child had profound hearing loss in her right ear and moderate hearing loss in her left ear; the aided threshold for both ears was within the speech spectrum. The assessment checklist for speech-language skills (ACSLS)[22] test was used to determine her language age. The ACSLS is a checklist designed to assess language comprehension and expression in children under 6 years of age. It includes items that evaluate both comprehension and expression at 3-month intervals from birth to 3 years, and at 6-month intervals from 3-6 years, with the resulting language age reported as a range. Before commencing DTT in May 2024, her Mean Length of Utterance (MLU) was 3.2, and her receptive language age was 2.7 to 2.9 years, and her expressive language age was 2.1 to 2.3 years. MLU was calculated using a picture description task and questions about daily routines to record responses. It took approximately three sessions to collect 100 utterances for MLU calculation. MLU was determined using the formula: total number of morphemes/total number of utterances.
After a detailed language assessment, highly functional language behaviours were chosen. The language behaviours treated included a) possessives (theirs-उनका), b) plurals (-s depending on the gender-याँ), c) conjunctions (and-और), and d) locatives (here-यहाँ, there-वहाँ). The participant was enrolled only after written informed consent and ethical approval were obtained from the AIISH ethics committee.
Baseline of the target behaviours
We base-rated each target behaviour (such as possessives, plurals, conjunctions, and locatives) using 20 picture stimuli, presented digitally with background animation across a) evoked trials and b) modelled trials. The evoked trials presented the pictures with a predetermined question, but did not model the child's response. Next, we presented the modelled trials, which asked the same predetermined question and modelled a full-sentence response (e.g., for plural, the question was "What are these?" and the modelled response was "Say 'These are cups'”). We calculated the percentage of correct responses for the 20 pictures in both the evoked and modelled trials.
All grammatical morphemes in the evoked trials showed 0% response accuracy, except for plurals, which demonstrated 70% accuracy. In the modelled trials, the child responded with 100% response accuracy for all the grammatical morphemes except for conjunction, which showed 65% accuracy. We chose the language goals of possessives, plurals, conjunctions, and locatives because none of them demonstrated a 90% response accuracy in the evoked trials.
Treatment Trials
After base rating, five exemplars from each chosen grammatical morpheme were treated to a 100% criterion. During the treatment trials, pictures were presented digitally with background animation, with a predetermined question. Each exemplar was modelled 5 consecutive times. When the responses from the child were positive, then evoked responses were initiated. The exemplar was considered trained when the child responded with 10 consecutive correct responses (100% criteria) for the evoked trials. The child’s responses to evoked stimuli were supported with a token economy, a positive reinforcement strategy to increase the likelihood of correct responses. For each correct response, the child received verbal praise followed by an emoji token. Upon collecting ten tokens, the clinician rewarded the child with either a cookie or an activity of their choice. We used a total of 80 trials for each of the five exemplars across the selected grammatical morphemes, but only 69 trials for plurals due to their high-modelled baseline.
Probe trials
After the five trained exemplars achieved 100% accuracy, we conducted an intermixed probe. This involved combining the five trained stimuli with 15 untrained stimuli, while only using the untrained stimuli in the pure probe. We generalised five exemplars to 15 untrained exemplars, surpassing our 90% response accuracy criterion.
Generalisation to other stimuli and settings
We conducted conversation probes to examine whether structured DTT training can be generalised to untaught but similar stimuli with varied settings. We examined the generalisation to the conversational level at: a) clinical settings and b) home. In this phase, the parents were encouraged to stimulate the target language behaviours that were established in the clinical setting into their daily conversations. Parents incorporated daily routines, such as preparing meals, to encourage the use of learned grammatical morphemes. They initiated conversations and asked questions using naturally available stimuli, such as real vegetables or clothes, at home. When the child responded, minor structural variations in language were accepted. Additionally, correct responses were occasionally reinforced with natural consequences, such as a smile or verbal approval from a parent, rather than using tokens or clapping. If needed, minimal prompting was provided at the beginning of the routine to encourage the use of the target grammatical morphemes. With regard to the conversational sample evoked in the clinic, picture cards and miniature objects were used instead of digital pictures, and questions were asked about the shown pictures, targeting the taught grammatical morphemes, and the same was video recorded.
As per prior information received from the clinician, two daily routines were video recorded as conversational samples, which were subjected to further analysis. Another investigator, an SLP who was not involved in this study, analysed the recorded data of the conversational probe. The SLP was informed about the target grammatical morphemes that had been taught to the child using DTT. A scoring sheet was used to record the number of opportunities provided by the parents during the conversation and the correct usage of the learned morphemes, which were counted by the SLP. Minor variations in sentence structure were accepted as long as the taught morphemes were used correctly (When the clinician modelled the target sentence as “This is their bottle”/je unka bɒtl heɪ/(यह उनका बोतल है), the child's response was accepted even if it was a shorter phrase, such as/unka bɒtl/(उनका बोतल), if the learned morphemes were used correctly). A percentage correct score was calculated using the data provided above.
Findings of conversational probes
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Clinical setting
Physical picture cards were used instead of digital animated pictures. There was a 62.5% (5/8) response rate for plurals; conjunction showed a 100% (4/4) correct response rate; Locatives (here, there) had a 57.14% response rate (4 correct responses for 7 opportunities), and the child did not use possessives in general conversation.
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Home setting
Parents used real objects and simple pictures at their home while recording the data instead of digital animated pictures. The analysed video showed that the child used plurals and conjunctions at a rate of 80% and 100%. Though they did not video record, parents reported that the child was using locatives and possessives at home consistently.
Findings of maintenance and rate of language development
We compared the response accuracy between pure probe post-treatment and maintenance after 20 days. Additionally, we recorded the rate of language development by measuring the pre-and post-treatment receptive and expressive language age and the MLU. All language behaviours showed a 100% maintenance rate in the comparison between the pure probes before and after treatment, except for the plural, which had a 93% production accuracy. This demonstrated that the child continued to meet our response accuracy criterion of 90% even after a 20-day break from DTT. The observed changes in language scores were measured using the ACSLS[22]. The checklist has been standardised on typically developing boys (n = 182) and girls (n = 183) below 6 years. Its reliability and sensitivity have been validated by comparing the norms with children who have hearing impairments and intellectual disabilities. According to the findings of ACSLS, changes were observed across both the language age and MLU between pre- and post-therapy following DTT. The receptive language age post-DTT was 4.1 to 4.6 years, and the expressive language age post-DTT was 3.7 to 4.0 years. The MLU increased to a score of 4 post-DTT, which was calculated using the conversational probe in the clinic and the home settings.
DISCUSSION
The results showed that structured approaches such as DTT assisted a child with a late cochlear implantation in quickly expressing grammatical morphemes and generalising them from trained to untrained exemplars. More than one year of change in the receptive and expressive language was observed, along with a significant increase in her MLU in a short span of 22 sessions. Providing didactic, structured language interventions such as DTT can offer multiple opportunities for practicing taught behaviours and their transferability to different settings.
Based on the findings of this study, we believe that DTT was effective in improving specific language skills within a short period and facilitated the transfer of learned language targets to natural speaking contexts. This study is one of the first to investigate DTT in aural rehabilitation for children with CI. The findings on the accelerated learning of selective language targets align with a prior study by Pomaville and Kladopoulos.[7] They reported that three adults with CI who went through behavioural speech therapy twice a week for four to five weeks were able to acquire the speech sounds rapidly. They also reported the generalisation and usage of trained speech sound targets in spontaneous speech.
Our finding of the rapid acquisition and generalisation of language treatment targets using DTT is supported by previous studies conducted on autism and other developmental speech and language disabilities.[8,23,24] A study that used both DTT to teach colour adjectives to children with autism found that DTT-mediated trials led to faster overall acquisition and better generalisation.[23] Similarly, a meta-analysis of single-case studies on language intervention in children with autism, which included both contrived approaches (e.g., DTT) and natural language treatments, demonstrated better generalisation with contrived approaches due to the increased opportunities for repetition.[24] Improved speech production accuracy during treatment and generalisation of the same to untrained words were also reported when a behavioural treatment was used for three children with apraxia.[8]
The timing of CI surgery influences overall language development in children. Numerous studies indicate that early implantation, particularly within the first two years of life, is crucial for achieving optimal language acquisition outcomes.[25-27] Although this study did not aim to compare language outcomes between children with early and late cochlear implants, its findings align with previous research suggesting that intensive, structured instruction enhances language abilities in children with late cochlear implantation and other developmental disabilities.[5,21,28,29] Such didactic instructions pave the way to developing incidental learning at a later stage of language development.
CONCLUSION
This study examined the effectiveness of DTT in improving the use of grammatical morphemes in a child with late cochlear implantation. DTT-facilitated rapid language acquisition, enabling the child to generalise learned grammatical morphemes from trained to untrained stimuli. Conversational probes conducted at home and in the clinic after the child had learned the grammatical morphemes demonstrated successful skill transfer. Additionally, the learned grammatical morphemes were maintained over a short follow-up period. Given these promising results, DTT may serve as a valuable tool for rehabilitating children with language delays due to late cochlear implantation.
This study had some limitations, as it involved only one participant with late cochlear implantation. While the results may be applicable to similar cases, further studies involving individuals who received cochlear implants at different ages, including those with early implantation, are needed to better understand the impact of DTT on language intervention. The follow-up period was short (20 days), so future studies should examine long-term outcomes. Also, treatment generalisation was seen only at home, suggesting the need for research in different natural speaking settings to better assess DTT’s effectiveness. Finally, as the evidence on overall language outcomes from structured language teaching and natural language methods in developmental disabilities is mixed, comparing these methods in children with different ages of cochlear implantation could provide insights into their relative effectiveness and potential role in aural rehabilitation.
Acknowledgement
We thank the Director of our Institute for allowing us to conduct this study.
Ethical approval
The study approved by the Ethics Committee under the Ethical Guidelines for Bio-Behavioural Research Protocol Involving Human Subjects at All India Institute of Speech and Hearing, bearing ref no. SH/IRB/M.1/SLP/37/2024-25, dated 6th September 2024.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
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