Frontiers in Psychology (Apr 2014)
Cross-modal priming facilitates production of low imageability word strings in a case of deep-phonological dysphasia
Abstract
Introduction. Characteristics of repetition in deep-phonological dysphasia include an inability to repeat nonwords, semantic errors in single word repetition (deep dysphasia) and in multiple word repetition (phonological dysphasia) and better repetition of highly imageable words (Wilshire & Fisher, 2004; Ablinger et al., 2008). Additionally, visual processing of words is often more accurate than auditory processing of words (Howard & Franklin, 1988). We report a case study of LT who incurred a LCVA on 10/3/2009. She initially presented with deep dysphasia and near normal word reading. When enrolled in this study, approximately 24 months post-onset, she presented with phonological dysphasia. We investigated the hypothesis that (1) reproduction of a word string would be more accurate when preceded by a visual presentation of the word string compared to two auditory presentations of the word string, and (2) that this facilitative boost would be observed only for strings of low image words, consistent with the imageability effect in repetition. Method. Three-word strings were created in four conditions which varied the frequency (F) and imageability (I) of words within a string: HiF-HiI, LoF-HiI, HiF-LoI, LoF-LoI. All strings were balanced for total syllable length and were unrelated semantically and phonologically. The dependent variable was as accuracy of repetition of each word within a string. We created six modality prime conditions each with 24 strings drawn equally from the four frequency-imageability types, randomized within modality condition: Auditory Once (AudOnce) – string presented auditorily one time; Auditory Twice (AudAud) – string presented auditorily two consecutive times; Visual Once (VisOnce) – string presented visually one time; Visual Twice (VisVis) – string presented visually two consecutive times; Auditory then Visual (AudVis) – string presented once auditorily, then a second time visually; Visual then Auditory (VisAud) – string presented once visually, then a second time auditorily. Strings were presented one word at a time via E-Prime software with a two-second delay between the two presentations of the string in the double-presentations. LT was cued with a picture and audio signal to reproduce the word string. She was given unlimited time to respond. Two replications of the experiment were completed. Results. We compared performance on the within and cross-modality presentation conditions for HiI, LoI, HiF and LoF word strings (Table 1). Reproduction of word strings in the Aud-Vis and Vis-Aud priming conditions was significantly more accurate than in the Aud-Aud priming conditions. This was observed for HiF word strings and LoI strings but not HiI strings. Additionally, the Vis-Vis prime and cross-modal prime conditions were not significantly different. Discussion. Using both auditory and visual presentation of word strings as primes (in either order) for reproduction of the word strings with low image words is more effective than an auditory prime presented twice. As predicted, this effect was not present for strings of high image words. We attribute this effect to increased support from the visual modality for low image words, which lack rich semantic representation and are more vulnerable to decay in the auditory form. Implications for improvement of auditory processing in deep-phonological dysphasia will be discussed.
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