After watching Ben Ridgway's "Continuum Infinitum" video, everything I looked at seemed to recede for a while. Ben recommends downloading the video and looping it.
As you watch the movie for a minute or so and then look away, you will experience a mild optical illusion that feels as if everything you look at is shrinking away from you. This is caused by the motion after-effect (MAE). It is a visual illusion experienced after viewing a moving visual stimulus for a time (tens of milliseconds to minutes) with stationary eyes, and then fixating on a stationary stimulus. The stationary stimulus appears to move in the opposite direction to the original (physically moving) stimulus. The motion aftereffect is believed to be the result of motion adaptation.
Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus; this is neural adaptation. Neural adaptation also reduces the spontaneous, baseline activity of these same neurons when responding to a stationary stimulus. One theory is that perception of stationary objects, for example rocks beside a waterfall, is coded as the balance among the baseline responses of neurons coding all possible directions of motion. Neural adaptation of neurons stimulated by downwards movement reduces their baseline activity, tilting the balance in favor of upwards movement.