Age of acquisition effects on spelling in surface dysgraphia

Weekes, Brendan and Davies, Robert and Parris, Ben and Robinson, Gail (2003) Age of acquisition effects on spelling in surface dysgraphia. Aphasiology, 17 (6-7). pp. 563-584. ISSN 0268-7038

Abstract

Background: It is not known whether the age of acquisition (AoA) of a word has any significant effect on the spelling performance of normal or impaired speakers. One way to explore this question is to examine the effects of AoA on surface dysgraphia. Aims: We report MK, a patient who suffered herpes simplex viral encephalitis (HSVE) resulting in semantic anomia and surface dysgraphia that we characterise as a tendency to produce a legitimate alternative spelling of a component defined as a LASC error. Methods & Procedures: We describe MK's neuropsychological profile, giving details of impaired naming, spoken and written word comprehension, written picture naming, oral reading, and spelling to dictation, but preserved repetition of whole words. We report experiments designed (1) to test the effect of AoA on spelling by controlling for word frequency as well as other correlated variables using logistic regression and ANOVA, and (2) to test the effects of AoA and sound to spelling predictability on MK's spelling. Outcomes and Results: The results show an effect of AoA but no independent effect of frequency on spelling and an interaction between AoA and predictability, i.e., an effect of AoA on unpredictable word spelling but no effect of AoA on predictable word spelling. Conclusions: We discuss these data with reference to accounts of AoA that locate the effect at the level of mappings between input (phonological) and output (orthographic) representations. We argue that the effect of AoA on spelling is not the result of lexeme activation per se but instead reflects the largely unpredictable mappings between sound and spelling that characterise the majority of English word spellings.