Semantic judgment of Chinese-Japanese bilinguals: A near-infrared spectroscopy study

We used functional near-infrared spectroscopy to investigate the role of the dorsolateral prefrontal cortex of bilinguals in semantic processing. Chinese-Japanese bilinguals and Japanese monolinguals judged if visually presented pairings of a word and a definition were Japanese. The four types of pairs appeared in Japanese and/or Chinese dictionaries: both, Japanese-specific, Chinese-specific, and neither. The bilinguals showed greater oxy-hemoglobin concentrations in their left dorsolateral prefrontal cortex for the Chinese-specific pair, while those in its right homologue were greater for the Japanese-specific, the Chinese-specific, and the neither pairs. These results imply that in the bilinguals, the left dorsolateral prefrontal cortex is related to reducing activation of semantic information in the nontarget language, while its right homologue focuses attention on the target language.