Lacking true depth perception, I’ve always been fascinated (and a little freaked out) by visual illusions — I am so curious about what I see that you don’t and what you see that I can’t. Check out this image from the Computational Visual Cognition Laboratory (part of the Perceptual Science Group, in MIT’s Department of Brain and Cognitive Sciences).
Close-up: you can see an angry man of the left and a woman with a neutral facial emotion on the right.Step back: the faces change expression and even genders!
This impressive illusion created by Dr. Aude Oliva and Dr. Philippe Schyns illustrates the ability of the visual system to separate information coming from different spatial frequency channels. In the right image, high Spatial Frequencies (HSF) represent a woman w69, 243-ith a neutral facial expression, mixed with the low spatial frequency information from the face of an angry man.
Or in other words, the images combine fine and coarse features, both of which are visible up close. At a distance, the fine features are harder to see, hence the “change.”
