What is the role of non-conscious information in decision evaluation?

For a long time, it was assumed that metacognition (the ability to reflect on one’s own decisions) depended on conscious access to information. However, recent studies suggest that the brain may continue to monitor and evaluate decisions even when we are not consciously aware of the stimuli that generated them.

In a study led by Liang Shan, 35 participants performed tasks involving active decisions (when making a choice) and passive decisions (when merely observing), while being exposed to visual stimuli that were conscious, subconscious, or absent. Brain activity was recorded using electroencephalography (EEG) and analysed with advanced multivariate pattern analysis (MVPA) techniques, which are sensitive to subtle neural activity patterns.

The results revealed an important finding: although participants’ behaviour did not distinguish between subconscious stimuli and no-stimulus conditions, the brain did. Traditional analyses of brain signals (event-related potentials, ERPs) showed no significant differences between these conditions, suggesting at first glance that no meaningful processing had occurred. However, more sensitive multivariate analyses uncovered distinct patterns of neural activity associated with conscious stimuli, subconscious stimuli, and the absence of stimuli.

Moreover, the findings demonstrated that subconscious information not only influences decision-making but also triggers a metacognitive process with distinct characteristics. Although it engages brain regions similar to those activated by conscious stimuli—particularly parietal and frontal areas—this processing differs in its temporal dynamics and signal strength, being faster and more robust when decisions are actively made.

These results suggest that the brain integrates and evaluates information that does not reach conscious awareness, indicating that part of decision monitoring operates automatically and outside conscious perception. The study, ““Subconscious information elicits distinct metacognition following Active Decision-Making”, was published in the journal Biomedical Signal Processing and Control as part of the research project 121/18 - Effects of subconscious, nonlocal, and retroactive information on participants’ choice/decision and neural activities, supported by the Fundação Bial.

ABSTRACT

Metacognition is often regarded as a sophisticated cognitive process that relies on consciousness. While both conscious and subconscious information impact decision-making, it remains unclear whether subconscious information can elicit post-decision metacognition to the same extent as conscious information. To clarify the post-decision metacognitive process under conscious and subconscious conditions and how they differ between active and passive decisions, 35 volunteers were recruited to participate in an actively making or passively watching decision task under conscious (Con), subconscious (SubCon), and no stimuli (None) conditions that utilized the continuous-flash-suppression paradigm. Brain activities were recorded from all participants using a 64-channel EEG system. In addition to analyzing ERPs, multivariate pattern analysis (MVPA) was employed to perform time-series decoding using the area under the receiver operating characteristic curve (AUC) as an indicator. While ERPs failed to reveal any significant difference, MVPA indicated that the metacognitive processing for SubCon and None differed from Con in the decoding AUCs. Further characterization of decoding metrics validated that SubCon was also different from None, demonstrating distinct metacognitive processing for subconscious information. Additionally, temporal generalization analysis illustrated the diverse neural dynamics among Con, SubCon, and None conditions, as well as between active and passive decisions. Finally, source localization analysis suggested the possible role of the frontal-parietal lobe in discerning post-decision metacognition. These findings demonstrate that subconscious information elicits distinct metacognitive processes post-decision-making, making a significant contribution to our understanding of metacognition.