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: http://faculty.washington.edu/chudler/benham.html

Here is another: http://www.exploratorium.edu/snacks/benhams_disk/index.html

Count the Dots

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

Count the black dots
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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: http://www.yorku.ca/research/vision/eye/hermann1.htm

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?