Implied motion from static photographs influences the perceived position of stationary objects.

A growing amount of evidence suggests that viewing a photograph depicting motion activates the same direction-selective neurons involved in the perception of real motion. It has been shown that prolonged exposure (adaptation) to photographs depicting directional motion can induce motion adaptation and consequently motion aftereffect. The present study investigated whether adapting to photographs depicting humans, animals, and vehicles that move leftward or rightward also generates a positional aftereffect (the motion-induced position shift--MIPS), in which the perceived spatial position of a target pattern is shifted in the opposite direction to that of adaptation. Results showed that adapting to still photographs depicting objects that move in a particular direction shifts the perceived position of subsequently presented stationary objects opposite to the depicted adaptation direction and that this effect depends on the retinotopic location of the adapting stimulus. These results suggest that the implied motion could activate the same direction-selective and speed-tuned mechanisms that produce positional aftereffect when viewing real motion.