Brain mechanism of cognitive conflict in a guessing Chinese logogriph task.

To investigate the neural substrates of cognitive conflict in high-level thought processing, we recorded event-related potentials while participants thought about the logogriph answers. We identified three states after the answers were provided: (1) the answer given was just what the participants initially guessed (No-aha answer). (2) Participants could understand the answer given correctly although they had not got the answer themselves (Aha answer). (3) Participants could not understand the correct answer offered (Uncomprehended answer). Results showed that, relative to the No-aha answer, the Aha and Uncomprehended answers elicited more negative event-related potential deflections between 250 and 400 ms. The dipole analysis localized the generator of the difference waves (Aha minus No-aha answer) to the anterior cingulate cortex. Thus, it might reflect the cognitive conflict center between familiar and new ways of processing the logogriphs.