Event-related potentials reveal the effects of altering personal identity

Subjects were presented with terminal words that identified a sentence to reflect their true selves or another irrelevant individual. Subjects were asked to push one button if the statement reflected their true identity and another if it did not. The ERP to the terminal word consisted of a double-peaked positivity. Both the initial P300 (peaking between 300–350 ms) and a later P550 (peaking between 550 and 575 ms) were significantly larger to words that reflected the subject's true identity. When subjects were asked to take on a new identity, the P300 became larger to new, false words but the later P550 was large to both the false and the true words. The P550 to true identity words became smaller over a period of 3 days as subjects rehearsed their new roles. However, the P550 remained large to the false identity words although it was now attenuated relative to the true identity words. The late positivities may reflect a complex decisional process involving at least two stages. The initial stage might the initial yes–no decision. The later positivity may reflect the personal relevance of the terminal word. In this case, one's own true identity only begins to lose its relevance after time, and enacting the false identity then increases the positivity to this new identity.