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Abstract
Deficits in CAS have been reported to be both linguistic-based and/or motor- based. This study attempts to dissociate the deficits by comparing a group of children exclusively diagnosed with Childhood Apraxia of Speech (CAS) to comorbid CAS and Specific Language Impairment (SLI) deficits and typically developing. A picture and word learning paradigm was used to test for differences in the semantic processing, early word learning, and speech production performance measures among children in each participant group. Semantic processing measured using visual memory task required the recognition of line drawings of unfamiliar objects (non-objects). The word learning task required the learning of 1- & 2- syllable pseudowords in two conditions: (a) auditory imitation condition – where one pair of 1- & 2- syllable pseudowords were presented auditorily, (b) semantic binding condition - where a different pair of 1-& 2- syllable pseudowords was presented with 2 non-objects. A comprehension probe used to measure early word learning assessed whether the child learned the object label during the semantic binding condition. Prerecorded auditory stimuli were presented pre- (before learning phase) and post- test (after learning phase) production. Repeated productions (both pre- and post- test) were analyzed using well-established transcription and kinematic measures of speech production. Specifically, the Spatial Temporal Index was used to quantify changes in articulatory spatiotemporal variability as a function of word learning and syllable lengths. Transcription measures of the same conditions include percent phoneme correct (PCC) and type token ratio (TTR). Results suggest that semantic binding during early word learning improved speech performance in children with CAS, which was most sensitive in kinematic level of analysis. Children with CAS didn't show evidence of language-based deficit but comorbid CAS and SLI deficits showed decreased performance in both semantic processing and early word learning, measured using visual memory task and comprehension probe scores.
