Why do you still feel the waves after getting off a boat? Why does the wall seem to come at you faster after you step off the treadmill? Why do the rocks seem to move upward after you stare at a waterfall? Why did people in the 1980s think their book pages had some red color in them… but no one thought that before or after the 80s? And what does any of this have to do with drugs, heartbreak, yellow sunglasses, or Aristotle watching a horse stuck in a river? Join Eagleman to understand how the brain constantly readjusts its circuitry to best read the world, and what it means for our (sometimes strange) perceptions of what’s out there.

Episode Audio

Episode Video

More Information:
Eagleman DM (2020). Livewired: The Inside Story of the Ever-Changing Brain. New York: Pantheon.

The McCollough Effect

Look at the image above, made up of green horizontal and red vertical lines. Stare at the colored lines for a bit: the red lines for a few seconds, then the green lines, then the red lines again, and then the green lines. Do this for about three minutes.

When you’re done, look at the black and white lines below. You’ll see that the spaces between the horizontal lines look reddish. And the spaces between the vertical lines look greenish.

Why? Because when you stared at the colored figure, your brain realized that greenness had become tied to horizontal and redness to vertical, and so it adjusted to cancel out this strange feature of the world. When you look at the black and white lines, you experienced the aftereffect: the horizontal lines were being internally shifted toward the opposite color – red – and vertical toward green.

The Troxler Effect


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