Wayfinding, displacements, and mental maps: velocity fields are not typically used to determine one's aimpoint

When an individual moves through a cluttered environment, he or she often fixates an object relatively near his or her path in the middle distance and uses pursuit eye movements to follow it while moving forward. On the basis of previous evidence, either motion fields or displacement fields around the fixated object--two alternative representations of the same information--could be used to determine one's direction of self-movement, sometimes called heading or aimpoint. In a series of 5 experiments, the relationship between these representations was explored and it was found that the displacements of identifiable objects, not their motions, are most likely the direct inputs for wayfinding. It may be that these inputs are used in conjunction with a mental map to determine one's aimpoint. A mathematical framework for this process is proposed.