Orthographic effects on picture naming in Chinese: A 4T erfMRI study

Abstract

The presence of a phonological relationship between a context word (cap) and the name of a target picture (cat) facilitates picture naming in the picture–word interference task in alphabetic languages such as English and Dutch. Neuroimaging studies of picture naming in English suggest distinct regions of brain activity are involved in pho- nological priming relative to a baseline control. Phonological priming of picture naming in English speakers is associated with a BOLD signal decrease in left Wernicke’s area and signal increases in anterior cin- gulate, orbitomedial prefrontal, inferior parietal cortices, and the oc- cipital lobe (de Zubicaray, McMahon, Eastburn, & Wilson, 2002). In alphabetic languages, orthography and phonology are unavoidably confounded. This makes it difficult to establish the relative contribu- tion of orthographic and phonological information to the facilitation effect. Therefore, it is not clear whether priming effects on picture naming are purely phonological or reflect additional orthographic processing, since the effect may be due to shared orthography rather than phonological overlap between target and foil. In non-alphabetic languages such as Chinese it is possible to examine the relative con- tribution of orthographic and phonological information to the facili- tation effect independently as many characters are heterographic homophones and others are visually similar characters that are not homophonous (Leck, Weekes, & Chen, 1995). This is of interest as most accounts of picture naming assume that phonological processing influences performance whereas at least some writers (e.g., Starreveld & La Heij, 1995) argue that orthographic information has an impact specifically at the lemma level. Weekes, Davies, & Chen (2002) re- ported independent effects on picture naming performance in Chinese when orthographically related and phonologically related foils are manipulated factorially and they showed that these effects do not in- teract. We know that recognition of characters is associated with specific patterns of activation in the cortex (Chee et al., 1999; Kuo et al., 2003). However, no study has reported the neural bases of pho- nological and orthographic priming on picture naming in Chinese. We report the results from an event related fMRI experiment investigating the independent effects of orthography and phonology on name re- trieval in five native Chinese (Putonghua) speakers.