We studied whether baseline cortisol is associated with post-error slowing, a measure that depends upon brain areas involved in behavioral inhibition. Moreover, we studied whether this association holds after controlling for positive associations with behavioral inhibition scores and error-related negativity (ERN) amplitudes that cortisol and post-error slowing may share. Healthy female volunteers performed a flanker task. Cortisol was independently positively associated with post-error slowing and the ERN, supporting hypotheses that cortisol is involved in behavioral inhibition. Additionally, cortisol mediated an association between ERN and more post-error slowing, which suppressed a direct association between ERN and less post-error slowing. The results are relevant, not only for researchers of behavioral inhibition, but also for researchers of the basic mechanisms of the ERN and post-error slowing, and may bring those literatures together.
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