Greater reliance on magnitude manipulation during mental arithmetic in deaf signers compared to hearing non-signers: fMRI evidence
2015 (English)Conference paper, Poster (Refereed)
Evidence suggests that the lag reported in mathematics for deaf signers derives from difficulties related to verbal processing of numbers, whereas magnitude processing seems unaffected by deafness. Neuroimaging evidence from hearing individuals suggests that verbal processing of numbers engages primarily left angular gyrus (lAG), whereas magnitude processing engages primarily the horizontal portion of the right intraparietal sulcus (rHIP). In a ROI analysis of brain imaging data from 16 adult deaf signers and 16 adult hearing non-signers, who did not differ on sex, age or education, we examined if activity in lAG and rHIP changed as a result of task (multiplication vs subtraction) and group (deaf signers and hearing non-signers). We found a significant main effect of brain region (F(1,30) = 117.00, p < .001, η_p^2 = .80) and an interaction effect between region and group (F(1,30) = 20.70, p < .001, η_p^2 = .41). Further analyses showed that there were no significant differences in average activation between groups in lAG (F(1,30) = 0.16, p = .70). However, in rHIP deaf signers showed significantly greater average activation compared to non-signers (F(1,30) = 15.20, p < .001, η_p^2 = .34). There were no significant differences in activation between subtraction and multiplication (F(1,30) = 0.66, p = .42) and no behavioural differences between groups (F(1,30) = 1.70, p = .20). These results suggest that when engaging in arithmetic tasks deaf signers successfully make use of qualitatively difference processes, compared to hearing non-signers, with stronger emphasis on brain regions relating to magnitude manipulation.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:liu:diva-123246OAI: oai:DiVA.org:liu-123246DiVA: diva2:878490
Conference on Cognitive Hearing Science for Communication (CHCCOM2015), Linköping, June 14-17, 2015