Last week we asked our readers about an illusion (created by Nobuyuki Kayahara) that’s been circulated very widely recently:
While the illusion can’t actually determine whether you’re “right-brained” or “left-brained,” we were curious about what actually affects people’s perception of the illusion. Over 1,600 readers took our online survey about the illusion. What’s interesting about the illusion is that it’s ambiguous — it can appear to be spinning both clockwise and counter-clockwise. Here’s how our readers saw it:
So roughly two-thirds of viewers initially saw it spinning clockwise, while a third saw it spinning counter-clockwise. About two thirds of viewers were able to reverse the direction of rotation from clockwise to counter-clockwise or vice-versa. Interestingly, this ability was affected by the initial direction of motion:
If you saw the figure spinning counter-clockwise first, then you were significantly more likely to be able to reverse the direction of rotation than if you saw it spinning clockwise first. This makes some sense, since more people see it rotating clockwise — it may be that there’s a natural tendency to see it spinning that way, which means it’s more difficult to reverse from clockwise to counter-clockwise than the other way around.
But are there any other explanations of who can reverse the spinning? We also asked viewers if they could perceive another common illusion, the “Magic Eye”:
(Click for a larger image) One method of perceiving the illusion is to move very close to the screen until the image is blurry, then move slowly away until you see a clear 3-D shape. Another is to look at the image cross-eyed and then shift back to normal vision.
Following these instructions, only about half of viewers were able to see the hidden image in this picture. Were people who could see the Magic Eye more able to reverse the dancer? Here are those results:
The effect is quite dramatic: people who can perceive the hidden Magic Eye image were significantly more likely to be able to reverse the dancer.
We asked a variety of other questions, testing for “color blindness,” asked about handedness, gender, age, video-game playing, computer preferences, and a cryptic question: “Do you know who or what TK-421 is?”
This last question is based on a fairly obscure bit of Star Wars trivia. TK-421 is the only Storm Trooper that is individually identified in the entire sequence of movies. Luke Skywalker had ambushed him and stolen his armor as a disguise, and he was later found out when a commander asked “TK-421, why aren’t you at your post?” We figured it might be possible that those who knew this bit of trivia were big Star Wars fans, and that might bear some relation to the ability to perceive the illusion. It didn’t, and none of the other factors we studied did either. However, there was a significant correlation between knowledge of this bit of trivia and time spent playing video games. This graph shows the relationship: