Synchronous and asynchronous perceptual bindings of colour and motion following identical stimulations.

When a moving surface alternates in colour and direction, perceptual couplings of colour and motion can differ from their physical correspondence. Periods of motion tend to be perceptually bound with physically delayed colours - a colour/motion perceptual asynchrony. This can be eliminated by motion transparency. Here we show that the colour/motion perceptual asynchrony is not invariably eliminated by motion transparency. Nor is it an inevitable consequence given a particular physical input. Instead, it can emerge when moving surfaces are perceived as alternating in direction, even if those surfaces seem transparent, and it is eliminated when surfaces are perceived as moving invariably. For a given observer either situation can result from exposure to a common input. Our findings suggest that neural events that promote the perception of motion reversals are causal of the colour/motion perceptual asynchrony. Moreover, they suggest that motion transparency and coherence can be signalled simultaneously by subpopulations of direction-selective neurons, with this conflict instantaneously resolved by a competitive winner-takes-all interaction, which can instantiate or eliminate colour/motion perceptual asynchrony.