“This is called the Troxler effect, after the man who discovered it: Ignaz Paul Vital Troxler, in 1804.
“What happens here is that your visual system constantly adapts to all the external stimuli. This is why after spending a few moments in the dark, you start to see a little better. This capability allows you to be in different lighting conditions, while still maintaining a pretty accurate estimate of the lightness and colour of objects.
“So if you fixate on a certain point, after approximately 20 seconds, stimuli which fit in your peripheral vision will fade away and disappear. The effect is most powerful for some colours and patterns, and is more powerful the farther the object is from your center of fixation…”
Text & Pic: Stare at this picture. It will disappear. ZMEScience.
Gefter: But how can seeing a false reality be beneficial to an organism’s survival?
Hoffman: There’s a metaphor that’s only been available to us in the past 30 or 40 years, and that’s the desktop interface. Suppose there’s a blue rectangular icon on the lower right corner of your computer’s desktop — does that mean that the file itself is blue and rectangular and lives in the lower right corner of your computer? Of course not. But those are the only things that can be asserted about anything on the desktop — it has color, position, and shape. Those are the only categories available to you, and yet none of them are true about the file itself or anything in the computer. They couldn’t possibly be true. That’s an interesting thing. You could not form a true description of the innards of the computer if your entire view of reality was confined to the desktop. And yet the desktop is useful. That blue rectangular icon guides my behavior, and it hides a complex reality that I don’t need to know. That’s the key idea. Evolution has shaped us with perceptions that allow us to survive. They guide adaptive behaviors. But part of that involves hiding from us the stuff we don’t need to know. And that’s pretty much all of reality, whatever reality might be. If you had to spend all that time figuring it out, the tiger would eat you.
Gefter: So everything we see is one big illusion?
Hoffman: We’ve been shaped to have perceptions that keep us alive, so we have to take them seriously. If I see something that I think of as a snake, I don’t pick it up. If I see a train, I don’t step in front of it. I’ve evolved these symbols to keep me alive, so I have to take them seriously. But it’s a logical flaw to think that if we have to take it seriously, we also have to take it literally.
Gefter: If snakes aren’t snakes and trains aren’t trains, what are they?
Hoffman: Snakes and trains, like the particles of physics, have no objective, observer-independent features. The snake I see is a description created by my sensory system to inform me of the fitness consequences of my actions. Evolution shapes acceptable solutions, not optimal ones. A snake is an acceptable solution to the problem of telling me how to act in a situation. My snakes and trains are my mental representations; your snakes and trains are your mental representations.
Text: Amanda Geftner, The Case Against Reality, The Atlantic.
Image: Huang Yong Ping, Ressort 2012