It’s a truism in cognitive psychology and neurobiology that “seeing” is not what happens in the eyes, but what is perceived by the “higher” brain centers. Our perceptual process largely consists of various brain centers removing information from the stream and pre-digesting it so that the decision-making and analysis parts of the brain are not overwhelmed by too much information. For instance, your visual cortex auto-corrects for lighting changes (like a good digital camera, only better) so you don’t even perceive the dramatic color shifting that “really” happens when the sun comes out from behind a cloud. That explains the famous white-and-gold dress that was really black-and-blue … or vice versa? The brain constantly corrects color perception for what it “thinks” (it isn’t really thought) the lighting is, and in this case can be fooled.
I just experienced a higher-brain-level version of this illusion. Not as dramatic or reproducible, but interesting.
I was looking at the front page of Wikipedia (for today as I write, April 14). The explanation of the featured image refers to scientist and philosopher Charles Sanders Peirce.
Quick: did you read his last name as “Pierce”? Dr. Peirce’s name was not spelled in the far more common way (as the standard spelling of a word meaning “puncture with a sharp object”). However, practiced readers of English will tend to read it as the standard spelling because we don’t consciously take the time to analyze the spelling of familiar words. We “sight read” by recognizing the overall pattern at a lower (subconscious) level and our consciousness receives only the meaning (and/or sound) of the word. That’s a perceptual illusion, like the dress illusion but from a different brain area. (Meaning-perception takes place chronologically after color-perception.)
I had a two-stage experience. I had actually heard of Peirce before, and recognized the name. I also misperceived it as “Pierce”. So my thought process was, “Hey, Wikipedia misspelled his name. I’d better correct it.” At that point, I looked back at it, with my perceptions tuned to perceive spelling instead of meaning, and immediately saw that it was correct in the first place. That brought my normal ability to ignore the shapes and order of the letters when reading to conscious attention, so I blogged about it.
I’ve always been fascinated by illusions, but this is one time I was blindsided by one I hadn’t thought about before.