It's Surprisingly Hard To Notice When Moving Objects Change
An anonymous reader writes "Scientists at Harvard have found that people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape. In a paper published yesterday (PDF) in Current Biology, the researchers present a new visual illusion that 'causes objects that had once been obviously dynamic to suddenly appear static.' The finding has implications for everything from video game design to the training of pilots."
I think this was fairly well known (at least intuitively) by magicians. As long as you keep your hands moving, people can't tell what you are doing with them.
Our eyes are trained to do a whole lot of quick thinking and estimates before sending the raw data to our brain. This is one of the many reasons why simply hooking a camera up to the optic nerve doesn't quite produce the desired results - though our brains seem to be super-learning computers able to interact with almost any other kind of Input - Output, given enough time for trial and error.
I imagine our Eyes are trained to generalize the colour it sees and focus on the appearance of motion, because thats usually more important and relevant to survival, and our eyes are just like technology: Limited bandwidth.
You might call it a defect, I might think of it as evolutionary design.
Switching something when it is in the middle of fast movement is the basis of all kinds of slight of hand tricks. There's just a certain state where the mind identifies something just as a blurb of overlapping color, rather than anything processed meaningfully, and you can freely swap it with a similar item without any notice. Mix in basic misdirection, and you can fool almost anyone's expectations. It's also why you kind of have to learn to juggle by feel & pattern rather than just sight - because the hand really does have to be faster than the (mind's ability to process information from the) eye to keep up with the pattern.
Ryan Fenton
The reef squid has the ability to quickly change colors and patterns on it's body, and seems to signal other squids in this fashion (as well as for camouflage). I wonder if they would be fooled by this illusion or if their neural optics are wired very differently than ours. It would be challenging to try to create an objective test that you could do with them.
hi, stupid scientist #1 here. (i'm one of the authors of the paper.) you're right, it would be nice to have a flash app that lets you change the speed of rotation. sadly, i programmed everything in MATLAB and I don't know flash. (and hey, didn't our overlord already pronounce flash dead?) on that note, if anyone knows flash and wants to program this up into an interactive demo, send me a message, i'm sure we could work something out.
but you're in luck, my friend. the demo works even if you pick up the screen and rock it back and forth, and i have a movie (link below) with no motion. you can loop the video and whirl the computer around all you'd like, at various speeds.
here's the movie.
as an aside, the first experiment in the paper in a speed manipulation. (spoiler alert.) the fast the ring rotates, the slower the dots seem to change.
I'd like to see if there's a culture bias to this. Get someone from a very non-westernized culture and ask what they see. They're regularly not fooled by these kinds of "illusions":
Which line is longer:
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Their eyes just aren't trained to see geometry the same way as westerners who are faced with tons of man-made things everyday.
"That which does not kill us makes us stranger." -Trevor Goodchild