Enhanced error-related negativity on flanker errors: error expectancy or error significance?

The present study investigated whether the error-related negativity, an electrophysiological marker for performance monitoring, reflects (1) the expectancy of errors, or (2) the significance of errors for the current task goal. In the first case, a larger error-related negativity is predicted for less expected errors, whereas in the second case, a larger error-related negativity is predicted for errors with greater significance. To test these predictions, we varied flanker size in a flanker task. With large flankers, more errors occurred by executing the response associated with the flankers (flanker errors) leading to a greater expectancy of flanker errors. As revealed by a multinomial model, these additional flanker errors represented highly significant attention errors, leading to an increased error significance. The error-related negativity was larger for flanker errors with large flankers, which supports the error significance account.