“Aha!” effects in a guessing Chinese logogriph task:An event-related potential study

In the present study,high-density event-related potentials(ERPs)were recorded to examine the elec-trophysiologic correlates of "Aha!" effects in a guessing Chinese logogriph task by using a two-stage model for learning-testing.Results showed that:Firstly Successful Guessing elicited a more negative ERP deflection(N350)than Recognition did in the time window from 300―350 ms after onset of the stimuli.A voltage map of the difference wave(Successful Guessing minus Recognition)showed strong activity at the front-central region.Dipole analysis localized the generator of the N350 in the vicinity of the posterior cingulate cortex(PCC)and the inferior frontal gyrus.Secondly,a greater late positive component(LPC)in Successful Guessing than Recognition was found between 600 and 700 ms post-stimulus.Dipole analysis localized the generator of LPC in the right parahippocampal gyrus.