Abstract:
Alcohol consumption attenuates both the behavioural adjustments and the heightened activity in the anterior cingulate cortex (ACC) which are normally observed following errors, leading to the hypothesis that alcohol disrupts the ability to effectively regulate the use of cognitive control. It has furthermore been theorized that these deficits may occur because alcohol reduces the negative affect elicited by unfavourable events, such as errors, thereby weakening the motivation to utilize cognitive control to improve performance. The aim of the current thesis was to provide an empirical test of this model. I carried out two studies in which I examined changes in two physiological indices of affective processing, skin conductance and heart rate, as well as behavioural and EEG responses, following errors on a flanker task. The first study was conducted on sober participants, in order to validate my experimental paradigm, while the second compared the physiological and behavioural effects of errors in participants given either alcohol or a placebo. In both experiments in both experiments, errors produced increased skin conductance responses and heart rate deceleration, and a typical error-related negativity in EEG. However, contrary to what would be expected if alcohol reduced the negative affect generated by errors, no difference in skin conductance or heart rate responses to errors were observed between alcohol and placebo participants in the second study. Furthermore, although intoxicated participants displayed an overall reduction in the use of cognitive control, based on both behavioural (flanker interference) and EEG (occipital alpha power) measures, groups did not differ in the degree to which this control was upregulated immediately after task errors. However, exploratory analyses of EEG indices (the feedback-related negativity and midfrontal theta power) of ACC activity following errors were significantly diminished in intoxicated participants. Overall, these findings suggest that alcohol does not reduce the immediate negative emotional consequences of errors but may instead disrupt brain networks needed for the sustained engagement of cognitive control and attention to task performance.
