Differential cerebral involvement in perceiving Chinese characters: levels of processing approach.

Three experiments were designed to determine the accuracy and latency with which right-handed Chinese university students (12 females and 12 males) recognized Chinese characters in the left and right visual half-fields (VHFs). The experiments varied in the "depth" of processing required. Experiment 1 was a lexical decision task in which the configuration of the stimulus (a real Chinese character or the mirror image of a real character) determined whether the grapheme was an actual character. Experiment 2 required phonological processing; i.e., subjects had to decide whether a character (or a foil) matched the sound of an orally presented Chinese character. Experiment 3 required semantic processing; i.e., subjects had to decide if a character (or a foil) belonged to a particular semantic category. In each experiment, single characters were presented unilaterally for 150 msec. There was a significant right VHF superiority for accuracy scores for Experiments 2 and 3 but not for Experiment 1. None of the experiments yielded significant visual asymmetries in reaction time. The results do not support previous claims of orthography-specific laterality, but instead show that laterality effects for morphemic stimuli vary with the orthographic, phonological, and semantic processing demands of the task.