The Nature of Error Consistency in Individuals With Acquired Apraxia of Speech and Aphasia.

PURPOSE: The primary characteristics used to define acquired apraxia of speech (AOS) have evolved to better reflect a disorder of motor planning/programming. However, there is debate regarding the feature of relatively consistent error location and type. METHOD: Ten individuals with acquired AOS and aphasia and 11 individuals with aphasia without AOS participated in this study. In the context of a 2-group experimental design, error consistency was examined via 5 repetitions of 30 multisyllabic words. The influence of error rate, severity of impairment, and stimulus presentation condition (blocked vs. random) on error consistency was also explored, as well as between-groups differences in the types of errors produced. RESULTS: Groups performed similarly on consistency of error location; however, adults with AOS demonstrated greater variability of error type in a blocked presentation condition only. Stimulus presentation condition, error rate, and severity of impairment did not influence error consistency in either group. Groups differed in the production of phonetic errors (e.g., sound distortions) but not phonemic errors. CONCLUSIONS: Overall, findings do not support relatively consistent errors as a differentiating characteristic of AOS.