Something about how seeing is not believing

May 20, 2014 10:26 AM

Every year, the Neural Correlates Association announces the world's three best optical illusions. Out of a number of finalists, the 2014 winners have been announced: 1) The Dynamic Ebbinghaus, 2) Flexible Colors, and 3) a Turn in the Road [animated gif version]. There are also a list of best illusions from all years, as well as winners from 2013, 2012, and previous posts. Of course, if there was a lifetime achievement award, it would need to go to Akiyoshi Kitaoka, inventor of some of the most amazing recent illusions: rotating snakes (seriously, this is amazing), possibly the best color illusion ever (with instructions on making them), and also Lady Gaga covers. Also, for no good reason, here are 20 more good ones.
posted by blahblahblah (38 comments total)

ahhhhhhhhhhhhhh flexible colors.
posted by entropone at 10:30 AM on May 20, 2014

In case it isn't clear, in the Dynamic Ebbinghaus, the circle in the center is always the same size. In Flexible colors, the colors between the black lines are gradients, but we see them as one color. The deal with Turn in the Road should be obvious.
posted by blahblahblah at 10:37 AM on May 20, 2014

I don't see the illusion in Flexible Colours (I always see the gradient), but the Turn in the Road one is amazing.
posted by jeather at 10:43 AM on May 20, 2014 [12 favorites]

A lot of these only work intermittently or work only when you're seeing the image out of the corner of your eye or what have you (like jeather, I mostly see the "flexible colors" one as color gradients, not as a single color). The "rotating snakes" just twitches for me when I look at it directly, but out of the corner of my eye I can see it rotate. The one that really boggles my mind is the "best color illusion ever" one--even in the blown up version I have to really stare to see that the color is constant in the two spirals.
posted by yoink at 10:48 AM on May 20, 2014 [2 favorites]

I thought plastic surgery would win for illusion of the year...followed by Botox, Spanx, etc...
posted by Alexandra Kitty at 10:57 AM on May 20, 2014

Of course, if there was a lifetime achievement award, it would need to go to Akiyoshi Kitaoka, inventor of some of the most amazing recent illusions: rotating snakes

I used to work in a visual perception lab; the first thing that comes to mind when I see a visual illusion is "What does this say about our visual system? What experiments could you do to explore the boundaries of the illusion (and our explanations of it)?"

But my reaction to the rotating snakes illusion is "GAH CLOSE THE WINDOW RIGHT AWAY SO NAUSEATING". I'm glad the lab never studied it.

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It's easy enough to "see through" flexible colors if you're foveating on (looking right at) the gradients. Look at the central circle to make it stronger.

Flexible colors immediately raises the question: is the important part of the black rings the discontinuity in luminance, or the discontinuity in saturation? You could construct a similar display with luminance-matched gray circles instead of black circles, and another with a semi-transparent brightening/darkening effect that maintained hue/saturation.
posted by a snickering nuthatch at 10:59 AM on May 20, 2014 [1 favorite]

Flexible colors is amazing!
posted by So You're Saying These Are Pants? at 11:03 AM on May 20, 2014 [1 favorite]

and cheers! I love this post, each time it comes around.
posted by So You're Saying These Are Pants? at 11:03 AM on May 20, 2014 [1 favorite]

I find Dynamic Ebbinghaus very underwhelming but the other 2, especially A Turn in the Road, very cool. Seriously, the minute that road slides over the second one, I'm like DAMN THIS EVIL DEMON MAGIC
posted by Hoopo at 11:20 AM on May 20, 2014

Turn in the Road is certainly clever, but it seems more like a trick question than an optical illusion. The phrase "roads that look different" is easily interpreted as "roads that point in different directions", in which case the viewer's naive assumptions are not at all incorrect.
posted by grog at 11:21 AM on May 20, 2014

I wish I had the technical skill to make up a bunch of digital "optical illusions" that looked like these but actually did move, change color or size, etc when you weren't looking.
posted by gottabefunky at 11:24 AM on May 20, 2014 [2 favorites]

The phrase "roads that look different" is easily interpreted as "roads that point in different directions", in which case the viewer's naive assumptions are not at all incorrect.


I'm not sure I follow. The reason the trick worked for me is that I identified the third road as the one pointing in a different direction. The first 2 look exactly the same to me, until they make the first one slide over the second and third ones.
posted by Hoopo at 11:26 AM on May 20, 2014

Yeah, Turn in the Road is a dead-simple dramatization of how perspective drawing works, but it's strikingly, surprisingly effective. It's my favorite. (Thanks for the post blahblahblah, I love seeing these every year.)
posted by straight at 11:27 AM on May 20, 2014 [2 favorites]

I'm not sure I follow. The reason the trick worked for me is that I identified the third road as the one pointing in a different direction. The first 2 look exactly the same to me, until they make the first one slide over the second and third ones.

The way in which they look the same is different from the way in which they slide. The way in which they look the same is by assuming a projection of 3d objects. The way in which they slide is by translating 2d objects without respect to any 3d projection.
posted by a snickering nuthatch at 11:37 AM on May 20, 2014 [1 favorite]

I so don't get the "roads" one. Does it just not work on me? I don't so any sort of illusion at all. The Flexible Colors though, pretty sure it started trying to communicate with me.
posted by Stonestock Relentless at 11:42 AM on May 20, 2014 [3 favorites]

That Turn in the Road is really effective as an animated .gif. Second only to this classic demonstrating the checkerboard shadow color illusion.
posted by straight at 11:45 AM on May 20, 2014 [1 favorite]

When the Rotating Snakes appeared here a few years ago, I printed it out on a color printer. Seeing it on a piece of paper is even more amazing than on a monitor.
posted by MtDewd at 11:45 AM on May 20, 2014 [3 favorites]

Second only to this classic demonstrating the checkerboard shadow color illusion.

That's my personal all-time favorite optical illusion. It's the one where, in my experience, people just flat out refuse to believe what you're telling them--and even when you open it in Photoshop and drive the point home they're still often suspicious that it's not all some sort of trick.
posted by yoink at 11:54 AM on May 20, 2014 [2 favorites]

Buried the lede on that first Lady Gaga link of cats reacting to optical illusions.
posted by maryr at 12:30 PM on May 20, 2014 [6 favorites]

Wow, the coffer one is really awesome. It's hard to say what's the "real" image and what's the illusion.
posted by ultraviolet catastrophe at 12:36 PM on May 20, 2014 [6 favorites]

I did look at the central circle; I absolutely still saw gradients.

The checkerboard shadow illusion is unreal. I can see people dragging a stripe of colour through so I know they have to be the same colour, but they just don't look it.
posted by jeather at 12:36 PM on May 20, 2014

"Best color illusion ever" is incredible.
posted by Golden Eternity at 1:04 PM on May 20, 2014

I find Dynamic Ebbinghaus very underwhelming

See, to me there's no way that central circle isn't changing size. It clearly got bigger and smaller. That issusion was the most compelling to me of the three. Really astonishing.

I saw the gradients in the Flexible Colors one, although the colors did appear to change size, and the gif moved too fast for me to really be able to process that the roads were the same shape (I guess; like I said, I couldn't tell).
posted by leahwrenn at 1:16 PM on May 20, 2014

"Waving beans" became the cover art for Merriweather Post Pavilion by Animal Collective.
posted by Pruitt-Igoe at 1:21 PM on May 20, 2014

The pigeon one is great! Click on 2014 finalists and they're all on one page.
posted by Mister_A at 1:22 PM on May 20, 2014

The checkerboard shadow illusions is literally why painting is difficult.
posted by overeducated_alligator at 1:40 PM on May 20, 2014 [1 favorite]

Don't miss the several videos available on Youtube of cats reacting to the rotating snakes illusion.
posted by ceribus peribus at 1:41 PM on May 20, 2014 [2 favorites]

You guys need to install the latest update, it has some fixes for the vision system.
posted by thelonius at 1:56 PM on May 20, 2014 [2 favorites]

Rotating Snakes was on the cover of some journal which sat prominently on the shelf in my library for quite some time and I had to flip the damned thing over if I was anywhere near it because constantly catching the motion out of the corner of my eye drove me nuts.
posted by Wolfdog at 2:54 PM on May 20, 2014 [1 favorite]

Oh, yeah, I see the boat! Ha ha ha! It's a boat in there! Wowsers!
posted by turbid dahlia at 4:10 PM on May 20, 2014

Tangentially related: I really enjoyed the game Monument Valley for iPad. It's short and not too hard but does a great job of integrating Escher-like illusions and geometric tricks into a game. My kids loved it too.
posted by freecellwizard at 5:42 PM on May 20, 2014 [1 favorite]

Man, looking at these with a head cold and fever really makes me want to lie down and die.
posted by BlueHorse at 6:59 PM on May 20, 2014 [1 favorite]

What is "Flexible Colors" supposed to do? It does nothing for me.
posted by popechunk at 9:06 PM on May 20, 2014

What is "Flexible Colors" supposed to do?

The illusion is that the areas between the black outlines are each filled in with a single uniform colour. But if you look closely, only the black lines are changing location on a multicolor background; they change to group different sets of colours together at different times. So if you stare at one spot, it seems to change color depending on which other shade it has been "outlined" with.

Flexible Colors has 3 different modes (circles, grid, tiles); click the left-right arrows if they don't cycle through on their own. Some modes work better than the others.
posted by ceribus peribus at 9:55 PM on May 20, 2014

"Best color illusion ever" (blue and green with spirals) has a closeup for explanation, but you can see it even more dramatically by zooming in the browser. At 150% it started to even out for me; by 200% they were identical. It reveals the effect in way that's easy to see.
posted by beerbudget at 8:20 AM on May 21, 2014

Isn't the "best color illusion ever" simply the same effect that allows the red, green, and blue sub-pixels in an LCD monitor combine to make white or any other color?
posted by straight at 9:24 AM on May 21, 2014

turbid dahlia: Oh, yeah, I see the boat! Ha ha ha! It's a boat in there! Wowsers!

It's a schooner.
posted by maryr at 11:00 AM on May 21, 2014

Isn't the "best color illusion ever" simply the same effect that allows the red, green, and blue sub-pixels in an LCD monitor combine to make white or any other color?

I may be wrong about this but I think subpixel blending happens in the optics of your eye (the light is already mixed by the time it is detected by the rods and cones in the retina). The Munker Illusion seems to be caused by spatial filtering later on in the visual pathway, perhaps related to the fact that such a small percentage of cones are s-cones?

Color shifts from S-cone patterned backgrounds: contrast sensitivity and spatial frequency selectivity - Steven K. Shevella, Patrick Monnierb
posted by Golden Eternity at 12:10 PM on May 21, 2014