The differential contribution of implicit and explicit priors during motion extrapolation

Accurately perceiving the position of moving objects is a fundamental prerequisite for interacting with the environment effectively. However, the brain is inherently “late” in doing so. By the time it encodes the position of a moving object, the object has already moved. To compensate, the brain exploits motion extrapolation, inferring the present position of an object from its past trajectory. Motion extrapolation arises from complex predictive processes, which combine sensory information with implicit and explicit priors to correctly estimate objects' positions. However, how implicit and explicit priors influence motion extrapolation remains unclear. The present studies aimed at understanding their differential contribution using a representational momentum paradigm combined with implicit and explicit priors about objects' motion speed, which in turn heavily impact motion extrapolation. Results showed a clear functional dissociation: while implicit priors resulted in adaptation to motion speed, explicit priors led to the reweighting of perceptual cues. These findings suggest that the representational format of prior information determines which subprocess of motion extrapolation is affected: while implicit priors apparently impact perception itself, explicit priors predominantly impact decision making.