Impact of emotionally-charged images and trial order on downstream cognitive processing: An ERP study

Theories of emotion-cognition interactions suggest that emotional valence can both facilitate or limit cognitive performance. One cause for the mixed findings may be the order (random versus non-random presentation) in which emotional stimuli are presented. To investigate the impact of stimuli order on cognitive control processing, EEG data were recorded as 130 undergraduate students (M age = 22.2, SD = 5.4; 79 female) completed a modified version of the AX-Continuous Performance Task in which the cue was followed by an emotionally-valenced image (positive, negative, and neutral). Specifically, the task was designed so that valenced images were presented in either a block or random order, prior to probe presentation. We examined two event-related potentials (ERPs), the N2, which reflects aspects of cognitive control, and the late positive potential (LPP), which reflects attention allocation to emotional stimuli. We assessed the impact of emotionally oriented attention (LPP) on downstream cognitive control (N2) and how this relationship might differ for a block versus random (order of emotional image) task design. Consistent with the LPP literature, we found a main effect of image valence with the negative trials showing larger LPPs than the positive and neutral trials. For N2s, we found that the negative trials were associated with smaller N2s than both the positive and neutral trials. We observed that as LPP amplitude increased, subsequent N2 amplitude was reduced, specifically for negative trials in the random design. These results suggest an emotion-related depletion of neural cognitive resources. Lastly, we found larger N2s for the block design versus the random design. Together, these results indicate the importance of paying attention to both trial order (block versus random) and within trial stimulus sequence when designing emotion induction tasks.