3 ms·

How does this work?

• Peroni 14y ago
  Due to the fact that you are seeing the faces in your peripheral vision for a brief moment, you don't have time to absorb all the detail of the face so your brain fills in the gaps based on memory. Your brain takes shortcuts so the results of 'filling in the gaps' are far from accurate.
  • zerostar07 14y ago
    That's why you don't even need the second image for this effect. The effect goes away if you focus on the actual image instead (using the mouse pointer as reference point)
• andrewcooke 14y ago
  my guess is that the brain does something like PCA, but then over-emphasizes the unusual components (probably because that's what makes each face distinct). in other words, the brain (either hard-wired or learnt) has an "average" face that it uses as a reference. when it has to handle a new face it doesn't "store" the whole face, but only the difference between the new and the average. so what much of your brain deals with is not "the face" but "differences of that particular face from the average". and somehow (see other replies) this illusion is able to connect that up to your conscious mind without the intermediate step that pads it back out by "adding in" the average.
• sp332 14y ago
  Your visual system (well really, all of your sensory inputs) have an effect called adaptation, where they "get bored" of any constant input. Your ears stop telling you about a constant hum, your skin stops telling you about the weight of your clothes, etc. So all the parts of the images that are the same, your optic system gets tired and just stops "seeing" them. So you can literally only see the parts that are different. It's a partial version of this effect: How to Blind Yourself Temporarily https://news.ycombinator.com/item?id=3992208 https://news.ycombinator.com/item?id=3992208