When conflict cannot be avoided: executive control dominates early selective sensory modulations during cognitive conflict

Abstract

AbstractWhen different sources of sensory information suggest competing behavioral responses, the efficiency of decision-making is impaired. Prior work suggests that at least two mechanisms may play a role in mitigating this interference: using early selective attention to extract the most relevant sensory inputs to avoid conflict or increasing the efficiency of the executive control network to resolve conflict during post-perceptual processing. To test these alternatives, we combined a stimulus-frequency tagging technique with a classic color-word Stroop paradigm, where color-bar targets and letter-string distractors were simultaneously flickered at different frequencies. Using electroencephalography (EEG), we measured the quality of early sensory processing by assessing the amplitude of steady-state visually evoked potentials (SSVEPs) elicited by the targets and distractors. We also measured the engagement of the executive control network by assessing changes in frontal theta (4-7Hz) and posterior alpha oscillations (8-14Hz). Counter to the ‘early selective sensory modulation’ account, the amplitude of the SSVEP response was not modulated by manipulations of color/word congruency, while the frontal theta activity increased and the posterior alpha activity decreased in response to conflict. Moreover, target-related SSVEP amplitude was not correlated with response times (RTs) and a higher (not lower) distractor-related SSVEP amplitude predicted faster RTs. On the other hand, the amplitude of the frontal theta and alpha activity was highly correlated with RTs, irrespective of conflict levels. Over all, these results highlight the dominant role of the executive control network in conflict resolution during post-perceptual processing.Significance StatementConflicting information interferes with decision-making. However, this interference can be mitigated either by extracting the most relevant inputs during early sensory processing or by increasing the efficiency of the executive control processes to resolve conflict. By measuring electroencephalography (EEG) in humans performing a modified color-word Stroop task, we examined early sensory responses evoked by targets and distractors while simultaneously monitoring frontal theta and posterior alpha oscillations to index the activation of the executive control network. We found evidence that the executive control network played a more prominent role in resolving conflict.