Objective: To compare the cortical mechanisms associated with visual spatial attention directed by location cues and Chinese character cues.
Method: Eleven healthy adults (mean age=19) with normal vision served as the subjects. In experiment I, the cue was a circle with black solid line. There were three cue sizes: small, medium and large. In experiment II, three black concentric circles were presented as background, their diameters were the same as the three cues used in experiment I. The cue was one of three Chinese characters small, medium or large respectively. The task of the subjects was to discriminate the target's orientation.
Result: RT in experiment II was longer with short ISI. The anterosuperior N1 amplitude elicited by the cue in experiment II was larger than that in experiment I. The inferoposterior P1 latency in experiment II was longer than that in experiment I. Comparing the target evoked ERP, the inferoposterior P1 and N1, latency of experiment II was longer than that in experiment I, the inferoposterior P2 amplitude in experiment II was larger than that in experiment I.
Conclusion: The processing of Chinese cue takes place at higher level functional brain regions compared to processing of location cue. The later requires more resource in the earlier stage of cue process and less in the subsequent stage of the task.