Ramp aftereffect

from Michael’s   Visual Phenomena & Optical Illusions


Warning: this is somewhat subtle.

What to do

Gaze for at least 10 s at the fixation cross in the neighbouring dynamic image. This will adapt your eyes to a brightening patch (above) and a repetitively dimming patch (below). Then click the mouse, or press the spacebar or tap the panel to turn both patches into a steady gray. You should see an aftereffect of apparent dimming (above) and apparent brightening (below) for a few seconds.

Another experiment:
Cover one eye, adapt, then stop the ramp (pressing space bar) and simultaneously switch eye cover. Does the aftereffect transfer to the unadapted eye?


This demonstrates the existence of transient visual pathways selective for the direction of gradual changes of luminance (on- versus off channels?).

Interestingly, this does not seem to exhibit interocular transfer (thanks, Frank), suggesting that this phenomenon has a purely retinal basis.


Based on Steward Anstis’s Demos with kind permission.

Anstis SM (1967, PDF) Visual adaptation to gradual change of intensity. Science 155:710–712

Arnold K, Anstis S (1993) Properties of the visual channels that underlie adaptation to gradual change of luminance. Vision Res 33:47–54

Hassan O, Georgeson MA, Hammet ST (2018) Brightening and Dimming Aftereffects at Low and High Luminance. Vision 2(2), 24