The Expected Discriminative Difficulty Affects The Amplitude Of The N2pc

The N2 pc component of the event-related potential(ERP) waveform provides a useful tool for directly assessing the locus of spatial attention. It is not clear that if N2 pc is modulated by difficulty of tasks in top-down search strategies. Here, the key manipulation was the discriminative difficulty in different task sets and the N2 pc effect was measured. Three discriminative difficulty conditions were setting in two tasks that whether the three discriminations were mixed presents in one block or not in this experiment(mixed task and pure task,). The result showed that higher amplitude of N2 pc was elicited only in the hard discriminative condition of pure task but not in mixed task. This finding indicates that theN2 pc cpmponent can be modulated by degree of attention that through top-down search strategies..