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.

Significance Statement Advancing the discipline: The study advances our understanding of consciousness by testing how far unconsciously perceived information can be used in decision-making. Identifying this potential boundary is important for understanding the nature of unconscious perception and the function of consciousness. Novelty: The novel aspect is that the experiment compares various levels of decision complexity without changing the settings of subliminal stimuli presentation. Previous analyses of the limits of unconscious perception were based on comparisons between different paradigms, which made conclusions more difficult to formulate. Importance: The study may influence discussions about the function of consciousness and may also provide support for theories of consciousness. It is relevant to researchers working on unconscious perception, evolution of consciousness, and theories of consciousness. Highlights Unconsciously presented premises influenced participants’ decisions. Three levels of decision complexity were tested: simple decisions without context, medium decisions with context, and complex decisions requiring inference. Decision accuracy declined as task complexity increased. Above-chance performance occurred only in the simple (58%) and medium (54%) conditions, while complex inference-based decisions were not reliably above chance. Information integration and logical inference may mark the limits of using unconsciously perceived stimuli.