Wiseheart, R. 1 , Park, H. 2 & Lombardino, L. 3
1 St. John's University, Queens, New York
2 Woosong University, Daejeon, Republic of Korea
3 University of Florida, Gainesville, Florida
Purpose: A long-standing hypothesis is that RAN taps the integrity of a phonological access mechanism; however, this has been difficult to prove. Using Rime Neighborhood Density as a proxy of phonological representation, we tested the effects of phonology on RAN using both object and digit stimuli. For both stimulus types, we predicted faster RAN times for words from high density neighborhoods because, according to lexical restructuring theory, competition from many similar sounding competitors causes words from dense phonological neighborhoods to become more accurately represented in the mental lexicon (Goswami, 2001). Method: 29 university students with dyslexia and 29 normal controls completed two experimental object and digit RAN tasks contrasted for rime neighborhood density. To ensure that digit naming reflected lexical retrieval speed and was not influenced by visual similarities of Arabic numerals, participants repeated the experimental digit RAN in a third task in which numerals (i.e., 6, 9) were replaced with written number names (i.e., six, nine). Results: For object RAN, both groups named high density words faster (p< .0001), consistent with previous research. Also as expected, the dyslexia group was significantly slower than the control group on both high density and low density object RAN. For digit RAN, however, there were no group differences and, surprisingly, digits from high density neighborhoods were named slower than digits from low density neighborhoods (p< .0001). Digit results were duplicated on the number word RAN task. Conclusion: Results for digit (and number) RAN were inconsistent with lexical restructuring theory, suggesting either1) phonological codes for digit names are acquired, stored, restructured, or retrieved differently than phonological codes for object names or2) a non-phonological lexical variable (e.g. semantics, frequency) underlies access to digits. Overall, these findings suggest that phonology affects digit naming in a very different way than object naming, even in dyslexic individuals.