Lexical decision performance in developmental surface dysgraphia: Evidence for a unitary orthographic system that is used in both reading and spelling

Abstract

The relationship between spelling, written word recognition, and picture naming is investigated in a study of seven bilingual adults who have developmental surface dysgraphia in both Greek (their first language) and English (their second language). Four of the cases also performed poorly at orthographic lexical decision in both languages. This finding is consistent with similar results in Italian that have been taken as evidence of a developmental impairment to a single orthographic system that is used for both reading and spelling. The remaining three participants performed well at orthographic lexical decision. At first sight, preserved lexical decision in surface dysgraphia is less easy to explain in terms of a shared orthographic system. However, the results of subsequent experiments showed clear parallels between the nature of the reading and spelling difficulties that these three individuals experienced, consistent with the existence of a single orthographic system. The different patterns that were observed were consistent with the claims of Friedmann and Lukov (2008. Developmental surface dyslexias. Cortex, 44, 1146-1160) that several distinct sub-types of developmental surface dyslexia exist. We show that individual differences in spelling in surface dysgraphia are also consistent with these sub-types; there are different developmental deficits that can give rise, in an individual, to a combination of surface dyslexia and dysgraphia. Finally, we compare the theoretical framework used by Friedmann and her colleagues that is based upon the architecture of the DRC model with an account that relies instead upon the Triangle model of reading].

Developmental surface dysgraphia without surface dyslexia

“…His spelling therefore shows all of the hallmarks of developmental surface dysgraphia. NK's reading performance is quite different from that of seven surface dysgraphics reported by Sotiropoulos and Hanley (2017b) who were all impaired at reading aloud the same set of irregular English words that NK read without difficulty. Four of them were poor at lexical decision, consistent with an impairment to the orthographic lexicon itself.…”

“…Controls scored 19.6/22 (sd = 1.9) at written picture naming and 20/22 (sd = 1.6) at spelling to dictation. Unlike two of the surface dysgraphic cases reported by Sotiropoulos and Hanley (2017b), therefore, NK was equally impaired at spelling the names of pictures and at spelling to dictation.…”

“…Production and comprehension of spoken words. In contrast to some surface dyslexics (Gvion & Friedmann, 2016) and surface dysgraphics (Sotiropoulos and Hanley, 2017b), NK showed no evidence of word finding Accuracy was unimpaired on a test of spoken word comprehension in which participants were asked to provide definitions of 68 spoken words. The same set of words was used in both languages.…”

“…Because the phonological pathway processes only a few irregular words, the correct pronunciations of most irregular words are generated by first activating their meaning from the orthographic units. Let us assume that the same processing units that are responsible for reading in this model are also responsible for spelling (for discussion, see Sotiropoulos and Hanley, 2017b). NK's poor spelling of irregular words indicates a developmental impairment to the semantics > orthography pathway in Figure 2.…”

“…This test was administered in English only. On some trials (see Sotiropoulos & Hanley, 2017b, for further details), he was shown a target word (e.g. fruit) followed by two homophones (e.g.…”