This article ([1]) discusses the phenomenon of “Change blindness”. Here is how the author describes it:
When Jeremy Wolfe of Harvard Medical School ... wanted to illustrate how the brain sees the world and how often it fumbles the job, he naturally turned to a great work of art. He flashed a slide of Ellsworth Kelly’s “Study for Colors for a Large Wall” on the screen, and the audience couldn’t help but perk to attention. The checkerboard painting of 64 black, white and colored squares was so whimsically subtle, so poised and propulsive. We drank it in greedily, we scanned every part of it, we loved it, we owned it, and, whoops, time for a test.
Dr. Wolfe flashed another slide of the image, this time with one of the squares highlighted. Was the highlighted square the same color as the original, he asked the audience, or had he altered it? Um, different. No, wait, the same, definitely the same. That square could not now be nor ever have been anything but swimming-pool blue ... could it?
The article came with a nice Flash animation, but that animation was static. It would be so much nicer to pick a random square and randomly change its color, or keep it the same. Greenfoot to the rescue.
It turns out that the flashing number that counts 1...2...3 is essential to distract the eye. It is also essential not to change one of the cream-colored squares, but we leave that as an exercise to the students.
Here is the project. It is pretty naive right
now. The Number instances should draw themselves rather than using images,
but I somehow had grief trying to draw outside the background image. The use
of JOptionPane isn't great. But it shows that Greenfoot can do a
lot more than have crabs
eat sandworms :-)
[1] Natalie Angier, Blind to Change, Even as It Stares Us in the Face, New York Times, April 1, 2008