Dual routes to cortical orienting responses: Novelty detection and uncertainty reduction

•Reactive and proactive orienting responses converge on a common neural pathway.•Frontal P3 activity can indicate task-relevant and task-irrelevant attentional orienting.•Novelty P3 and Uncertainty P3 are negatively correlated.•Novelty P3 and Uncertainty P3 can be dissociated based on brain-behavior correlations.•Distractibility is characterized by large Novelty-P3 and small Uncertainty-P3 amplitudes.

Sokolov distinguished between reactive and proactive variants of the orienting response (OR). The Novelty P3 is considered as an electrophysiological signature of the reactive OR. Recent work suggests that the proactive OR is reflected in frontally distributed P3 activity elicited by uncertainty-reducing stimuli in task-switching paradigms. Here, we directly compare the electrophysiological signatures of reactive and proactive ORs. Participants completed a novelty oddball task and a task-switching procedure while the electroencephalogram was measured. Novel and uncertainty-reducing stimuli evoked prominent fronto-centrally distributed Novelty P3 and Uncertainty P3 waves, respectively. We found a substantial negative correlation between Novelty P3 and Uncertainty P3 across participants, suggesting that reactive and proactive ORs converge on a common neural pathway, but also that distinguishable routes to orienting exist. Moreover, response accuracy was associated with reduced Novelty-P3 and enhanced Uncertainty-P3 amplitudes. The relation between Novelty P3 and Uncertainty P3 might serve as an index of individual differences in distractibility and cognitive control.

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