Effects of age of acquisition on brain activation during Chinese character recognition

The age of acquisition of a word (AoA) has a specific effect on brain activation during word identification in English and German. However, the neural locus of AoA effects differs across studies. According to Hernandez and Fiebach [Hernandez, A., & Fiebach, C. (2006). The brain bases of reading late-learned words: Evidence from functional MRI. Visual Cognition, 13(8), 1027-1043], the effects of AoA on brain activation depend on the predictability of the connections between input (orthography) and output (phonology) in a lexical network. We tested this hypothesis by examining AoA effects in a non-alphabetic script with relatively arbitrary mappings between orthography and phonology--Chinese. Our results showed that the effects of AoA in Chinese speakers are located in brain regions that are spatially distinctive including the bilateral middle temporal gyrus and the left inferior parietal cortex. An additional finding was that word frequency had an independent effect on brain activation in the right middle occipital gyrus only. We conclude that spatially distinctive effects of AoA on neural activity depend on the predictability of the mappings between orthography and phonology and reflect a division of labour towards greater lexical-semantic retrieval in non-alphabetic scripts.