Perception of heading during rotation: sufficiency of dense motion parallax and reference objects.

How do observers perceive the path of self-motion during rotation? Previous research suggests that extra-retinal information about eye movements is necessary at high rotation rates (2-5 degrees /s), but those experiments used sparse random-dot displays. With dense texture-mapped displays, we find the path can be perceived from retinal flow alone at high simulated rotation rates if (a) dense motion parallax and (b) at least one reference object are available. We propose that the visual system determines instantaneous heading from the first-order motion parallax field, and recovers the path of self-motion by updating heading over time with respect to reference objects in the scene.