Benham Disc

Even with the reduced size and resolution of this short clip, you can probably see the intended effects.

  • Watch the disc. Describe what you see … do you see shapes? Colors?
  • As the rotation slows, do the shapes and colors change? How so?
  • If others are watching at the same time … compare what you see with what they see.
  • What does this do to the conventional wisdom that “seeing is believing”?
  • Where do the “rings” and “colors” exist? (They’re ‘manufactured’ by your nervous system.)
  • This suggests that “color is in the eye of the beholder.” What does this imply for all adjectives and descriptions?
  • View more visual misperception demonstrations by neurobiologist Christof Koch here.

Here is a visual explanation for the effect by Blue Man Group, from “Inside the Tube”:

Here is a basic explanation for the effect:

Here is another:

Count the Dots

For this exercise, all you have to do is count how many black dots you see.

Count the black dots
If you think you’ve experienced some kind of electronic perception manipulation, try printing the previous page, look at the graphic on paper, and see if you get similar results …

What’s going on?

David Hewson in Australia reported that this is referred to as “Hermann’s Grid” and is explained (somewhat) at:

What’s the point?

I would say this exercise illustrates the following:

  • We can ‘see things’ that aren’t there.
  • What we ‘see’ is not just a function of our eyes; what we ‘see’ results from what our visual-brain-system detects, processes, and reports.
  • Even when we ‘know’ that our visual-brain-system is ‘lying’ to us, we cannot overcome it – we continue to see black dots (or even colored ones)
  • Given this clear demonstration of how our senses can sometimes fool us, perhaps we should exercise a bit more tentativeness and skepticism when we are tempted to fall victim to “seeing is believing”, because …
  • If we ‘see’ black dots when there are only white dots … what else do we ‘see’ that’s not there? At home, at work, in our relationships, among friends, etc. Can you recall a situation in which you saw what wasn’t there; heard what wasn’t said; understood what wasn’t intended?

What else came up for you in this exercise? What lessons do you take away?