How the depth of processing modulates emotional interference - evidence from EEG and pupil diameter data.

The ability to process emotionally conflicting information is an important requirement for emotional self-control. While it seems obvious that the impact of interfering emotional information critically depends on how deeply this interfering information is processed, it is still unknown what cognitive subprocesses are most affected by manipulating the depth of processing of emotionally interfering information. We examine these aspects integrating neurophysiological (EEG) and source localization data with pupil diameter data as an indirect index of the norepinephrine (NE) system activity. We show that when processing depth of interfering emotional stimulus dimensions is increased, emotional Stroop effects become stronger. The EEG data show that this was associated with modulations of decision-making processes, as reflected by the P3 event-related potential. Notably, the integration with pupil diameter data suggests that these decision processes were modulated by the NE system, especially when the depth of processing of interfering emotional stimulus dimensions was increased. This likely reflects gain modulation processes to facilitate processing of complex interfering, emotional information. The source localization results suggest that regions in the parietal (BA7) and insular cortex (BA13) are associated with these modulatory effects. The results suggest that overcoming more complex emotional interference triggers engagement of the norepinephrine system (indexed by pupil diameter) to facilitate action control mechanisms in a time-specific manner when deeper processing of emotional stimulus dimensions is required.