The mechanism of interaction between visual flow and eye velocity signals for heading perception

A translating eye receives a radial pattern of motion that is centered on t he direction of heading. If the eye is rotating and translating, visual and extraretinal signals help to cancel the rotation and to perceive heading c orrectly. This involves (1) an interaction between visual and eye movement signals and (2) a motion template stage that analyzes the pattern of visual motion. Early interaction leads to motion templates that integrate head-ce ntered motion signals in the visual field. Integration of retinal motion si gnals leads to late interaction. Here, we show that retinal flow limits pre cision of heading. This result argues against an early, vector subtraction type of interaction, but is consistent with a late, gain field type of inte raction with eye velocity signals and neurophysiological findings in area M ST of the monkey.