Pupil dilation indexes - but does not causally influence - conscious error detection: a double-blind, placebo-controlled investigation of performance-monitoring using atomoxetine.

BackgroundConscious error detection is accompanied by error-related changes in phasic autonomic activity. This autonomic response is diminished in older age - accompanied by impairments in the conscious detection of action errors - i.e., increased error blindness. Indeed, the degree to which the autonomic response to errors declines across the lifespan is correlated with the increase in error blindness. However, the direction of causality - whether changes in autonomic reactivity are a consequence or cause of increased error blindness - is still debated. In the present study, we experimentally modulated the phasic autonomic response to action errors in healthy older adults while measuring their conscious error detection. MethodsAcross two sessions, thirty healthy older adults (60-80 years old) were given the sNRI atomoxetine or placebo in a double-blind fashion. In each session, they performed an anti-saccade task, which is commonly used to test conscious error detection. The autonomic response to errors was measured via changes in pupil dilation. A novelty-oddball task was also employed as a manipulation check. ResultsAtomoxetine reduced phasic pupil dilation to both novel stimuli in the novelty-oddball task and to action errors in the anti-saccade task. However, despite this blunting of the phasic autonomic response to errors, there were no significant differences in conscious error awareness between atomoxetine and placebo. Primary task performance was also unaffected. ConclusionsDespite its effects on phasic autonomic activity after errors, atomoxetine had no effect on conscious error detection in healthy older adults. This suggests that phasic autonomic activity is a consequence, rather than a contributing factor, to conscious error awareness. It also suggests that changes to phasic autonomic activity is unlikely to explain increased error blindness in older age.