Tracking contingency unconsciously

Extracting statistical regularities from the visual environment is crucial for survival. Here we show that our visual system can track the location contingency between an unconscious and a conscious item over a lengthened period of time. In a series of psychophysical experiments, we adopted an exogenous priming paradigm and manipulated the location contingency between a masked prime and a visible target. That is, how likely the prime location predicted the target location. Critically, the prime was further shown to be invisible both subjectively and objectively. However, although the participants were unaware both to the existence of the prime and the prime-target contingency, our results showed that the contingency was tracked and affected the subsequent priming effect. When participants were first entrained to the fully predictive prime-target contingency, later faster responses to the highly predictive location were found. On the contrary, when no contingency existed between the prime and target initially, later faster responses were found to the lowly predictive location. These results were replicated in two more experiments with increased statistical power and a fine-grained delineation of prime awareness. Together, we report that human visual system is capable of tracking unconscious contingency over a long period, extending the known flexibility of unconscious processing.