To what extent does our unconscious experience with a temporal correspondence between two stimuli from different modalities influence how we subsequently perceive them? We addressed this question by exposing participants two different geometrical figures (a circle and a triangle; presented unpredictably) and a tone, for 5min. While the circle was consistently presented 700ms before the tone, the triangle always appeared in a completely uncorrelated fashion with respect to the tone. In two test blocks, conducted one before and the other one after the 5-min exposure phase, participants performed simultaneity judgments (SJs) regarding the circle and the exposed tone or else the triangle and the tone presented at different stimulus onset asynchronies (SOAs). The results revealed that, even if participants were unable to detect any conscious association between the stimuli presented after the 5-min exposure phase, they significantly accepted less time between the ‘associated figure’ (the circle) and the tone than between the ‘non-associated figure’ (the triangle) and the tone to judge them as being simultaneous, after exposure. Furthermore, a small but significant temporal realignment was also observed between the 2 unconsciously associated stimuli after the 5-min exposure phase. This pattern of results indicates that the preconscious establishment of perceptual links between visual and auditory stimuli modulates the subjective temporal perception of these stimuli.

crossmodal association, temporal adaptation, unconscious perception