EEG evidence for the effective proactive control of emotional distraction
Recent behavioural studies using an emotional flanker task have found that task-irrelevent emotional images are more distracting than neutral images under infrequent, but not frequent, distractor conditions.It has been proposed the effective control of distraction in the high distractor frequency condition may be due to a shift to a proactive control strategy, whereby a potential distraction is anticipated and minimised in advance. However, although it is well established that proactive control is effective at reducingneutral distraction, it is not yet clear whether emotional distraction can be effectively proactively controlled. In this thesis, I used EEG to measure pre-stimulus indices of proactive control in order to determine whether proactive control is responsible for the effective control of emotional and neutral distraction in the high distractor frequency condition, as well asto examine whether proactive control differs according whether a neutral or emotional distraction is anticipated.In addition to replicating the previous behavioural findings, posterior EEG alpha was found to be tonically suppressed in the high compared to low distractor frequency condition, strongly supporting the hypothesis that proactive control was engaged in the high distractor frequency condition. By contrast, there was no difference in phasic alpha suppression (i.e., the drop in alpha in response to fixation onset) between conditions, indicating that the more effective control of distraction in the high frequency distractor conditions was due to a sustained proactive control strategy, rather than greater trial-by-trial preparation to attend to the target. In addition, no alpha lateralisation was found, indicating the mechanisms by which distraction was proactively controlled did not include the preparatory suppression of expected distractor locations. Finally, tonic alpha did not differ according to the expected distractor valence, but phasic alpha suppression was more pronounced when negative, compared to neutral or positive, distractors were expected, independent of distractor frequency condition. This suggests proactive control was also used to some extent in the low distractor frequency condition, but more importantly also provides initial evidence that the proactive control of negative distraction may be unique. Taken together, my findings provide compelling evidence that emotional distraction can be effectively proactively controlled. Future research is needed to determine the mechanisms by which this occurs, and whether the proactive control of emotional distraction is particularly effortful.