Poster E86, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall
Differences between deaf and hearing readers of Chinese are limited to the right superior temporal cortex
Junfei Liu1,2,3,4, Tae Twomey1,2, Yiming Yang3,4, Mairéad MacSweeney1,2;1Institute of Cognitive Neuroscience, University College London, 2Deafness, Cognition and Language Research Centre, University College London, 3Jiangsu Key Laboratory of Language and Cognitive Neuroscience, 4School of Linguistic Sciences and Arts, Jiangsu Normal University
Reading is a challenging task for deaf readers of alphabetic orthography such as English (Cawthon, 2004) and also of Chinese (He, 2005). Previous studies have reported both differences and similarities in the neural responses between deaf and hearing readers of Chinese during explicit semantic and phonological tasks on written words. However, it is still unclear whether deaf and hearing readers of Chinese recruit the same network during reading. For example, deaf readers may rely on semantics more than phonology, due to reduced auditory experience. However, phonological knowledge is less important than semantic knowledge in reading Chinese since the orthography generally maps more closely to semantics than phonology. Behaviourally, semantic bias has been observed in hearing readers of Chinese (Williams & Bever, 2010). This suggests that the neural network recruited by deaf and hearing people may be similar when they read Chinese. Using functional magnetic resonance imaging, we contrasted the neural responses in Chinese deaf and hearing adults. We used a lexical decision task, which does not emphasise the use of semantic or phonological knowledge. We predicted that the reading network recruited by deaf and hearing readers of Chinese would be similar given that the orthography is semantically biased. Twenty-four hearing and 24 deaf adults viewed a sequence of real single-character Chinese words (n=120) and pseudo-characters (n=120), presented for 0.5 second each (ISI=1~4 second; mean=2.5 second). Participants made a button press to indicate whether it was a real character or not. They were also tested on Chinese reading, with a test developed based on the Vernon-Warden Reading Comprehension Test of English (Vernon-Warden, 1996). The reading scores were included as a covariate in the imaging analyses following a significant group difference: deaf participants (M=63.1%; SD=11.3%) were poorer readers than hearing participants (M=82.9%; SD=11.3%), t(46)=6.08, p<0.001, d=1.75. There were no significant differences between groups on reaction times or accuracy. The conjunction analysis of deaf and hearing groups identified bilateral ventral occipito-temporal cortices, left precentral gyrus, left central operculum and left supplementary motor area. The only group difference was found in the right superior temporal cortex (STC), in the anterior (x=54, y=8, z=-7; Z=5.38, p=0.001 FWE, k=12) and the middle (x=63, y=-19, z=2; Z=4.97, p=0.010 FWE, k=3) portions. At these peaks, activation in the deaf group was significant while the responses in the hearing group did not differ from the baseline. The current study shows that when deaf and hearing readers of Chinese read, statistically reliable differences between the groups are limited to the right STC. This effect is likely to be associated with deafness since task performance did not differ between the groups; and the reading level was included as a covariate. Consistent with previous studies (e.g., Finney, Fine & Dobkins, 2001; Twomey et al., 2017), this effect may reflect low-visual processing in the deaf group. Our results also suggest that semantically biased orthography might minimise hearing status effects during reading. Future studies are needed to directly contrast different orthographies and investigate the influence of orthography on reading in deaf people.
Themes: Reading, Meaning: Lexical Semantics
Method: Functional Imaging