Age-of-acquisition effects in pure alexia

Abstract

Pure alexia is an acquired reading disorder in which previously literate adults adopt a letter-by-letter processing strategy. Though these individuals display impaired reading, research shows that they are still able to use certain lexical information in order to facilitate visual word processing. The current experiment investigates the role that a word's age of acquisition (AoA) plays in the reading processes of an individual with pure alexia (G.J.) when other lexical variables have been controlled. Results from a sentence reading task in which eye movement patterns were recorded indicated that G.J. shows a strong effect of AoA, where late-acquired words are more difficult to process than early-acquired words. Furthermore, it was observed that the AoA effect is much greater for G.J. than for age-matched control participants. This indicates that patients with pure alexia rely heavily on intact top-down information, supporting the interactive activation model of reading.

Keywords:

• Age of acquisition
• Pure alexia
• Reading
• Eye movements

Acknowledgments

This research was conducted as part of a Senior Honors Thesis project at Skidmore College by the first author under the direction of the second author. Special thanks are extended to G.J. for his patience and participation in this project. We would like to thank Maxine Dunne and Morgan Eisler for their assistance with data collection. Additionally, we would like to thank Andrew Ellis for his comments on a previous draft of this paper and Marlene Behrmann for her helpful comments when this research was presented at the 2009 Psychonomic Society meeting in Boston.

Notes

¹ Prior to running the current eye-tracking study, G.J. also participated in a naming task in which he was asked to name these well-controlled experimental items as quickly but as accurately as possible. Early-acquired words were named more quickly (M = 7,024 ms) than late-acquired words (M = 8,737 ms). This difference was statistically significant, t(34) = 2.12, SEM = 808.53, p = .02, suggesting that G.J. shows an effect of AoA where late-acquired words are more difficult to process than early-acquired words.

² Lexical ratings for Celex frequency (Baayen, Piepenbrock, & Gulikers, 1995), bigram frequency, trigram frequency, and orthographic neighbourhood size were obtained using N-Watch (Davis, 2005). Kučera–Francis frequency (Francis & Kučera, 1982), letter confusability, number of letters, number of syllables, AoA, imageability, familiarity, and concreteness ratings were obtained from the MRC (Medical Research Council) database (Coltheart, 1981). Cumulative frequency was calculated as the sum of the frequency of a word across all grade levels. Measures were obtained from the Educator's Word Frequency Guide (Zeno, Ivens, Hillard, & Duvvuri, 1995).

³Sentences were read aloud so that G.J.'s reading errors could be identified and removed from data analysis. Prior research suggests that G.J.'s eye movements were quite similar when reading silently and when reading aloud (Rayner & Johnson, 2005).