Weaker error signals do not reduce the effectiveness of post-error adjustments: Comparing error processing in young and middle-aged adults

In this study we investigated age-related differences in error processing, comparing performance measures and physiological indicators of error processing of middle-aged (41–59 years) and young (18–31 years) adults using a version of the Eriksen flanker task. Although middle-aged participants were overall slower, both groups showed a comparable decrease in reaction time on error trials as well as slower and more accurate post-error performance. Despite the preserved error speeding and post-error slowing effects, we found an amplitude reduction in the Ne/ERN, contradicting the existence of a direct relationship between the amplitude of this component and post-error adjustments. This was further supported by the lack of significant correlations between the single-trial Ne/ERN amplitude and error-related reaction times. The single-trial Ne/ERN distribution showed a reduced variance for middle-aged compared to young participants, suggesting that weaker overall error signals rather than lapses in error detection are responsible for the observed Ne/ERN amplitude reductions. However, we argue that the signal still reached the necessary threshold to trigger normal post-error adjustments. Finally, the early Pe showed a reduction in amplitude and an increase in latency for middle-aged compared to young adults. Together, the findings suggest clear signs of a physiological decline in error processing at an earlier age than previously known, but these changes do not yet affect implementation of adaptive behavioral changes in middle-aged participants.