Recent findings showed that an unpredictable context increases the amplitude of the Error-Related Negativity (ERN), a cognitive Event-Related Potential (ERP) that appears after the commission of an error. Interestingly, this effect has only been studied using unpredictable, performance-unrelated stimuli. In many situations, however, it is the consequence of the error itself that is unpredictable. The present study examined how predictable and unpredictable punishment intensity contingent on error commission differentially modulated ERN amplitudes. Using high-density EEG, we recorded the ERN in 40 healthy volunteers while they performed an arrowhead version of the Eriksen flanker task under three conditions: Errors were either consistently punished with (1) predictable nonpainful, (2) predictable painful, or (3) unpredictable (50% painful/50% nonpainful) electrical stimulation. Furthermore, we examined whether individual differences in trait anxiety modulated the effect. Contrary to our predictions, ERN amplitudes did not differ across conditions, nor were there any differences between low and high anxiety groups. Nevertheless, the effects of predictability and intensity were present in Somatosensory Evoked Potentials (SEPs) elicited by the punishments. N1 amplitudes were increased for painful compared to nonpainful stimulation. P2 amplitudes were increased for painful compared to nonpainful, and for unpredictable compared to predictable stimulation, whereas the Late Positive Potential (LPP) was increased for unpredictable compared to predictable stimulation. Overall, these results demonstrate that unpredictability and increased painfulness of punishment (1) enhanced the potential motivational significance of the errors, but (2) did not potentiate ERN amplitudes beyond the ones elicited by errors punished with predictable nonpainful stimulation.
