Last week’s Casual Friday study was all about illusion. For example, you may have thought our goal was to see how well you could recognize an illusion. However, we really just wanted to know what kind of computers our readers use:
Amazingly, Cognitive Daily readers use Macs at a rate (22.8 percent) about seven times higher than the U.S. market share of Apple Computers (roughly 3 percent).
We did also want to know something about how you see illusions, so we designed a simple experiment based on a brilliant illusion by Akiyoshi Kitaoka. If you haven’t visited his web site full of astonishing illusions, why not head over there now? We’ll still be here in a couple hours, when you’re finished.
Our experiment was based on this illusion:
When most people view this figure, which is in fact a static image, it appears as if the diamonds in the outer rings are slowly moving clockwise (to the right). The diamonds in the inner rings seem to be moving counter-clockwise (to the left). But if you view an extremely faded version of the same image, you almost certainly won’t see any motion at all:
For our experiment, we divided participants into four roughly equal groups by asking for their birth month. One group saw the original, unfaded illusion, and the others saw progressively more faded versions of the same picture, with the final group seeing the most faded version we showed you above. Here’s what viewers said they saw:
As you might expect, viewers saw progressively less motion as the illusion faded. Impressively, even at the highest level of fading, some viewers saw the motion and correctly identified the direction of the motion. I had predicted that there might be a difference between Mac and Windows users, since often the same image appears darker on a Windows machine, however, we could find no significant difference between computing platforms.
We did notice one startling finding based on handedness. None of the left-handed users made an error of direction of motion:
When the right-handers’ “can’t remember” responses are combined with incorrect motion direction responses, the difference is significant. Is there some difference in the visual system of left-handers that explains this? Are left handers more careful than right handers? And why are so many Cognitive Daily readers Mac users? We invite your speculation in the comments.