Faces, English words and Chinese characters: a study of dual-task interference in mono-and bilingual speakers

Abstract

The many-to-many hypothesis suggests that face and visual-word processing tasks share neural resources in the brain, even though they show opposing hemispheric asymmetries in neuroimaging and neuropsychologic studies. Recently it has been suggested that both stimulus and task effects need to be incorporated into the hypothesis. A recent study found dual-task interference between face and text functions that lateralized to the same hemisphere, but not when they lateralized to different hemispheres. However, it is not clear whether a lack of interference between word and face recognition would occur for other languages, particularly those with a morpho-syllabic script, like Chinese, for which there is some evidence of greater right hemispheric involvement. Here, we used the same technique to probe for dual-task interference between English text, Chinese characters and face recognition. We tested 20 subjects monolingual for English and 20 subjects bilingual for Chinese and English. We replicated the prior result for English text and showed similar results for Chinese text with no evidence of interference with faces. We also did not find interference between Chinese and English text. The results support a view in which reading English words, reading Chinese characters and face identification have minimal sharing of neural resources.

Keywords: Chinese; Multilingual; Object recognition; Perceptual expertise; Word processing.

Fig. 1

Examples of stimuli used in the alternating dual-task experiment. A 8 different facial expressions in two examples of different face identities. B 8 different fonts in three examples of different English word identities. C 8 different fonts in two examples of different Chinese character identities. D 6 different colored ellipses

Fig. 2

Examples of alternating dual-task experimental trials. A Baseline trials: colors with faces/words. Target task was either visual word/face identity recognition or color recognition. B Face/word trials: target task was either face identity recognition or visual word identity recognition. C Similar trials: faces with faces or words with words. Target task was the same within a block. D Word/word trials: English words with Chinese characters. Target task was English or Chinese character identity

Fig. 3

Results for face identity recognition. In these and all subsequent graphs of results the baseline condition is the white bar on the left and the maximal interference condition the grey bar on the right, with conditions of interest in the middle. Top: accuracy when the alternating ‘interfering’ stimuli were colors (the baseline condition). English words, Chinese characters, or other faces (the ‘similar’ condition with maximal interference). Bottom: reaction times. Error bars show the standard error. Horizontal lines show pair-wise contrasts that were significant

Fig. 4

Results for English word reading. Top: accuracy when the alternating ‘interfering’ stimuli were colors, faces, Chinese characters, or other English words. Bottom: reaction times. Error bars show the standard error. Horizontal lines show pair-wise contrasts that were significant

Fig. 5

Results for Chinese character reading. Top: accuracy when the alternating ‘interfering’ stimuli were colors, faces, English words, or other Chinese characters. Bottom: reaction times. Error bars show the standard error. Horizontal lines show pair-wise contrasts that were significant