Facilitating Word-Learning Abilities in Children with Specific Language Impairment
Thesis DisciplineSpeech and Language Therapy
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Children with Specific Language Impairment (SLI) often present with difficulties in learning new words compared to age-matched children with typical language development. These difficulties may affect the acquisition, storage, or retrieval of new words. Word-learning deficits impact on children’s vocabulary development and impede their language and literacy development. Findings from a wide range of studies investigating word-learning in children with SLI demonstrated that semantic and phonological knowledge are crucial to the word-learning process. However, intervention studies designed to improve the word-learning abilities in children with SLI are sparse. The experiments described in this thesis addressed this need to understand the effects of interventions on word-learning abilities. Further, the thesis describes the first investigation of word-learning abilities of New Zealand school-aged children with SLI. Specifically, the following three broad questions are asked:
1. What are the word-learning skills of New Zealand school-aged children with SLI compared to children with typical language development and which underlying language skills influence word-learning? 2. What are the immediate and longer term effects of phonological awareness and semantic intervention on word-learning and language skills in children with SLI? 3. What are the error patterns of children with SLI compared to children with typical language development when learning to produce new words and do these patterns change following phonological awareness and semantic intervention?
The first experiment compared the word-learning abilities of 19 school-aged children with SLI (aged 6;2 to 8;3) to age-matched children with typical language development and revealed that children with SLI presented with significant difficulties to produce and to comprehend new words. After repeated exposure, children with SLI caught up to the performances of children with typical language development in learning to comprehend new words, but not on production of new words. Correlation analyses demonstrated that there were no correlations between the word-learning skills and other language measures for children with SLI, whereas the word-learning abilities of children with typical language development were correlated to their phonological awareness, semantic, and general language skills. In the second experiment, it was investigated whether there were also qualitative differences during word-learning between children with and without SLI additionally to the quantitative differences as revealed in the first experiment. Children’s erroneous responses during the word-learning tasks were categorised into phonological, semantic, substitution or random errors. A comparison of the children’s error patterns revealed that children with SLI presented with a different error pattern and made significantly more random errors than children with typical language development. However, after repeated exposure, children with SLI demonstrated a similar error pattern as children without SLI. Furthermore, it was examined whether a specific combination of phonological and semantic cues facilitated children’s learning of new words or whether there were word-specific features that facilitated children’s word-learning. No facilitative word-specific features could be identified. Analysis revealed that there were no significant effects of cueing on learning new words, but specific patterns could be derived for children with SLI. Children with SLI learned to comprehend more words that were presented with two semantic cues or one phonological and one semantic cue and learned to produce more words that were presented with two phonological cues. In the third experiment, the effectiveness of a combined phonological awareness and semantic intervention to advance children’s word-learning abilities was examined. Nineteen children with SLI (same participants as in experiment 1) participated in this intervention study that implemented an alternating treatment group design with random assignment of the participants. Children in group A received phonological awareness intervention followed by semantic intervention, whereas children in group B received the same interventions in the reverse order. Children’s word-learning abilities were assessed at pre-test, prior to the intervention, at mid-test after intervention phase 1, and at post-test, immediately following the completion of the second intervention phase. Each intervention itself was effective in significantly improving children’s fast mapping skills, however, gains in children’s word-learning abilities were only found for children in group A for production of new words. Extending the findings of the intervention effectiveness of phonological awareness and semantic intervention on word-learning as reported in experiment 3, it was investigated in experiment 4, whether the implemented intervention additionally influenced the error patterns of children with SLI. The erroneous responses of children with SLI on all word-learning probes at pre-, mid-, and post-test were categorised into the same error groups as described in the second experiment (semantic, phonological, substitution, and random errors). The error analyses revealed that children’s error profiles changed during the course of intervention and treatment specific effects on children’s erroneous responses were found. Post-intervention, children who received phonological awareness followed by semantic intervention displayed the same error patterns as children with typical language development, whereas children who received the same interventions in the reverse order maintained the same error pattern as displayed at pre-test. The final experiment examined the longer-term effects of the combined phonological awareness and semantic intervention reported in experiment 3 on the language and literacy development of children with SLI. Eighteen of the 19 children with SLI, who received the intervention reported in experiment 3, were available for re-assessment 6 months after the completion of the intervention. The children (aged 7;1 to 9;2 years) were re-assessed on a range of standardised and experimental measures. Data analysis revealed that 6 months post-intervention, all children were able to maintain their gains in phonological awareness, semantic, and decoding skills as displayed immediately after the intervention. Children’s general language and reading skills significantly improved following the intervention; however, children who received phonological awareness intervention followed by semantic intervention displayed significantly better reading outcomes than the children who received the same interventions in the reverse order. This thesis revealed that a combination of phonological awareness and semantic intervention can enhance the word-learning abilities of children with SLI. The combined intervention approach was also effective in additionally improving children’s general language skills and the reading of single non-words and real words, as well as connected text. The immediate and longer-term intervention effects provide evidence that advancing the semantic and phonological awareness skills is an effective intervention approach to support children with SLI in their word-learning and to furthermore promote their language and literacy development. However, the order of the implemented interventions played a significant role: Children in the current study profited most when they received phonological awareness intervention first, followed by semantic intervention.