Repeated attempts, phonetic errors, and syllabifications in a case study:Evidence of impaired transfer from phonology to articulatory planning

Abstract

Background: In aphasia, impairments affecting stages after lexical access have been subdivided into three types: 1. impairments specifying a sequence of phonemes after lexical access (the reproduction variety of conduction aphasia, CA); 2. impairments holding on to these representations during articulatory planning (the shortterm memory (STM) variety of CA); and 3. Impairments specifying integrated articulatory/motor plans for clusters of phonemes (apraxia of speech, AoS). Models of speech production, however, suggest more articulated possibilities (i.e., different subtypes of articulatory impairments). Aims: We investigated the impairment in a person with aphasia whose preliminary assessment revealed mixed speech characteristics, combining features typically used to identify CA -phonological errors across tasks and repeated attempts at the target -with features typically used to identify AoS -phonetic errors and word dysfluencies (phoneme elongations and syllabifications). Our preliminary hypothesis was that there was a difficulty transferring information from an (intact) phonological output buffer to articulatory planning. Slow/noisy transfer would predict dysfluencies, errors selecting motor programs, but also repeated attempts (RA) at revising the output in the face of intact feedback and intact original representations. This hypothesis also predicts effects of position and phonological complexity. Method and Procedure: We tested CS's word and nonword repetition, word reading, and picture naming. We quantified lexical and non-lexical errors, repeated attempts, phonetic errors, and syllabifications. We assessed effects of word frequency, word length, phoneme position, and syllabic and phonological complexity. Results: CS made similar errors across tasks, consistent with a postlexical impairment. His RAs most often built up a correct target from fragments and/or previously incorrect attempts, similar to a conduite d'approche. He also produced more errors in later positions, and more repeated attempts on longer words. However, inconsistent with decay from an output buffer, phonological errors did not increase with word length. Finally, frequency mattered, ARTICLE HISTORY

Effects of delay, length, and frequency on onset RTs and word durations: Articulatory planning uses flexible units but cannot be prepared

“…These results confirm with additional materials the impairment hypothesized for CS by Ramoo et al (2021). CS shows an impairment across all production tasks.…”

“…The case of CS has been extensively described in a single-case study (Ramoo et al, 2021). The characteristics of his speech production indicate that his main difficulty occurs after lexical access.…”

“…He was recruited for a research study via the South Birmingham Community Support Centre of the Stroke Association and was tested at the University of Birmingham between 2012 and 2014. A detailed case study of CS is described in Ramoo et al (2021). We refer readers to this paper for additional details and only summarize here the main features of his performance necessary to motivate the present investigation.…”