Lexical influences on single word repetition in acquired spoken output impairment: A cross language comparison

Abstract

Background: Among the many factors that may affect speech production, phonological neighbourhood density (ND) and phonotactic probability (PROB) have displayed effects on speech and language performance in healthy speakers. What is not clear is if they show an effect in impaired speech output after stroke and if they do, whether this effect is facilitatory or inhibitory. Aims: To determine whether ND and/or PROB play a role in speech production accuracy in acquired output impairment after stroke. To compare the performance of English vs German speakers on a matched set of words in order to tease out language‐specific and language‐independent factors affecting impaired speech output. Methods & Procedures: Seven English and seven German native speakers with acquired output impairment after stroke repeated in their respective languages 509 real words that are (near) homophones across German and English (e.g., leader–Lieder; vine–Wein). Responses were transcribed phonetically and scored as correct or incorrect. Results & Outcomes: There was a small correlation between accuracy on near‐homophones between English and German speakers (r = .201; p < .001). Correlating accuracy for speakers combined across both languages with language‐independent factors (i.e., number of phonemes, syllables, clusters) showed significant independent effects of number of phonemes and clusters in the target, but multiple regressions did not show an effect of number of syllables. Within‐language correspondence was greater than between‐language correspondence (9.4% vs 4%; p < .00001). Correlating differences in accuracy in English/German with differences in language‐specific factors (i.e., word and syllable frequency, PROB, ND) multiple regression displayed a significant independent effect of the target's word frequency but not of the target's ND, PROB, or syllable frequency. Conclusions: The small but significant correlation between accuracy on (near) homophones for English and German speakers suggests there are language‐independent determinants of production accuracy, whereas greater within‐language correspondence indicates language‐specific determinants of performance. Only word frequency appears to have a significant (facilitatory) effect on response accuracy. Neither ND nor PROB had a significant effect on response accuracy in this study. The results are discussed in light of theoretical and methodological issues within the study.