Is it possible to make unconscious inferences? The limits of the influence of unconsciously perceived stimuli on conscious decisions.

Abstract

Stimuli presented outside conscious awareness can influence behavior, yet the extent to which such information supports complex decision-making remains unclear. The present study examined the limits of unconscious influence across three levels of decision complexity. Participants made decisions based on stimuli presented using sandwich masking. Stimulus presentation parameters were held constant across conditions, while decision requirements varied. Simple decisions required no contextual integration, intermediate decisions required the integration of masked information with consciously presented context, and complex decisions additionally required logical inference. The results showed that decision accuracy decreased with increasing complexity: it was highest in the simple condition (58%, with strong Bayesian evidence for above-chance performance), lower but still above chance in the medium condition (54%), and not reliably above chance in the complex condition. This suggests that unconscious influence can extend beyond simple decisions but becomes increasingly unreliable when decisions require more demanding integration or inferential processing. Our findings indicate that one of the functional roles of consciousness may be to support the flexible use of information in higher-order cognitive processes and are broadly consistent with theoretical approaches such as the Global Neuronal Workspace Theory.