Slide Slam D5
The critical role of phonology in sentence-level writing and reading: Evidence from aphasia, alexia, and agraphia
Alyssa Sachs1, Kindle Rising1, Chelsea Bayley1, Katlyn Nickels1, Pélagie Beeson1; 1University of Arizona
INTRODUCTION: Phonological alexia and agraphia are well-described syndromes reflecting damage to sublexical phonology-orthography correspondences. The hallmark features of poor nonword reading and spelling are associated with damage to left perisylvian cortical networks; however, practical implications of phonological impairment have received limited attention. Friedman (1996) observed disproportionate text-level reading errors on grammatical words and morphological markers in individuals with phonological alexia. Similarly, Beeson and colleagues (2018) documented effects on sentence-level writing, suggesting that phonological text alexia and phonological text agraphia are complementary disorders affecting everyday written language skills in those with acquired phonological impairment. Here, we tested the hypothesis that phonological skills would predict sentence-level reading and writing abilities in a heterogeneous cohort with damage to the left perisylvian language network (i.e., the dorsal pathway). METHODS: We evaluated data from a comprehensive language assessment from 41 individuals with acquired aphasia, alexia, and agraphia due to damage in left perisylvian cortical regions. There was a range of aphasia severity (16.7-96.4 AQ) and significant impairment of central linguistic skills (semantics and phonology) in relation to an age-education matched control group (n = 49). Speech production and handwriting were also impaired but adequate for intelligible/legible output. Composite scores were derived for: Semantic knowledge; Phonological awareness/manipulation skills; Speech production ability estimated from spoken repetition of words/nonwords; and Handwriting ability estimated from allographic conversion task (transcoding letters from upper-to-lowercase and vice versa). To examine text-level written language, we analyzed written picture descriptions of the picnic scene from the Western Aphasia Battery from all those with aphasia. Oral reading was evaluated in a subset of 20 individuals using a 100-word passage. Separate regression models were computed to examine the following dependent measures: Written picture description--Content information units (CIUs); Informativeness (CIUs/total words); Efficiency (CIUs/minute); and Proportion of grammatically well-formed and complete sentences // Oral reading--Total number of errors (deviations from the printed word); Reading errors on function words and morphological markers; and Reading errors on open class words. RESULTS: Individuals with aphasia were significantly impaired on all measures of sentence-level writing and reading. For written narratives, phonological skill consistently emerged as a significant independent predictor of all four dependent measures (CIUs [β=.460, p=.003], informativeness [β=.385, p=.004], efficiency [β=.453, p=.008], and grammatical form [β=.568, p<.001]). Handwriting skills (allographic conversion) also contributed to written informativeness (β=.386, p=.002). With respect to reading, phonological skills were the only significant predictor of overall reading errors (β=-.552, p=.017) and errors on closed class words and morphological markers (β=-.546, p=.025). In contrast, reading accuracy of open class words was not predicted by phonological skills (β=-.429, p=.055). CONCLUSION: This study affirmed the critical contribution of phonological skills to sentence-level written language ability. In particular, phonological performance, as measured by phonological awareness and manipulation tasks, strongly predicted content, efficiency, informativeness, and grammatical form of written sentences. The effects of phonology on reading were less robust but were more critical than the status of semantic knowledge or speech production abilities. Overall, these findings are consistent with complaints from individuals with chronic aphasia regarding persistent written language difficulties.