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kottke.org posts about optical illusions

The Train Speed Optical Illusion

posted by Jason Kottke   Jun 06, 2023

If you watch the video above of a front-facing camera on a moving train, the train appears to move much faster in the zoomed out view than in the zoomed in view. Here’s what’s going on:

The illusion that speed decreases when zoomed is “because when one focuses on an inner portion of the movie, the optic flow angular speed is slow, and appears to fill one’s entitle visual field, which is consistent with overall lower forward speed.

Note: The more zoomed, the more densely packed the overhead rigging appears. So, even though you appear to be moving forward more slowly when zoomed in, the actual rate of rigging flowing by remains constant, consistent with same forward speed in all conditions.

(via the kid should see this)

The Best Illusions of 2023 Contest

posted by Jason Kottke   Jun 05, 2023

The mind-boggling winners of the Best Illusion of the Year Contest for 2023 have been announced. The entries for each the ten finalists include a video that demonstrates each illusion and then shows how it works. The top prize winner is this working model of Platform 9 3/4 from the Harry Potter books:

One of my favorites is The Poggendorff Triangles, which goes to show you that straight lines aren’t always straight:

Here’s an audio illusion that sounds as though the tempo is endlessly rising (similar to the Shepard tone):

And then there’s this hollow face illusion in which this woman’s face looks at you as you move around her:

You can check out the rest of the finalists here.

The Best Optical Illusions of the Year

posted by Jason Kottke   Feb 11, 2022

The winners of the Best Illusion of the Year Contest for 2021 have been announced and among the top 3, the one that really baked my noodle is the second place winner, Michael A. Cohen’s Changing Room Illusion:

I caught a tiny bit of what was going on here — it’s a bit like the invisible gorilla experiment — but the full reveal shocked me. First place was The Phantom Queen and The Double Ring Illusion took third. You can find a list of winners on the front page of their website and a list of the 10 finalists here.

All These Balls Are the Same Color?!

posted by Jason Kottke   May 04, 2021

optical illusion where several balls that appear to be the same color actually aren't

Oh dear, this illusion just totally broke my brain. No can write now. Somehow all same ball colors. What world? What earth? Why live? (Even after reading and seeing the explanation, I had to drag this into my photo editing app to verify it with my own eyes. True true. Oh, humanity.) (via @flyosity)

Healing Grid Optical Illusion

posted by Jason Kottke   Apr 28, 2021

Healing Grid

Healing Grid is an optical illusion by Ryota Kanai that was a finalist in the 2005 Best Illusion of the Year Contest. If you stare at the center of the image for several seconds, the broken edges start to “repair” themselves in your peripheral vision. Explains Kanai: “This illusion seems to indicate the preference of the visual brain to see regular patterns.” (via @stevesilberman)

Update: Kanai and several co-authors later wrote a scientific paper about this illusion: The Uniformity Illusion: Central Stimuli Can Determine Peripheral Perception.

We argue that the uniformity illusion is the result of a reconstruction of sparse visual information (from the periphery) based on more readily available detailed visual information (from the fovea), which gives rise to a rich, but illusory, experience of peripheral vision.

(via @kanair)

Rotating Circles Optical Illusion

posted by Jason Kottke   Nov 27, 2020

This is one of the best optical illusions I’ve ever seen: aside from rotating, these circles don’t move.

The left/right/up/down arrows were freaky enough but the in & out arrows really blew a gasket in my brain. For proof that the circles don’t move, blink your eyes quickly as you watch or check out this gif. (via @jagarikin)

A Mind Sang

posted by Jason Kottke   Jul 06, 2020

A Mind Sang is an inventive short film about “perception, rebirth, and transformation”. What I most liked about watching was how effortless it was to see the transitions between all the optical illusions — but it wasn’t too easy. A great sense of pacing by filmmaker Vier Nev. Read an interview with Nev about his film on Vimeo’s blog. (via @mikeindustries)

The Best Optical Illusion of the Year for 2019

posted by Jason Kottke   Dec 16, 2019

This mind-bending optical illusion concocted by Frank Force has won this year’s Best Illusion of the Year contest. The illusion features a moving shape that somehow can be seen to rotate around both the horizontal and the vertical axis and rotates in two different directions around each axis. W. T. A. F.

An unusual take on the M.C. Escher cube optical illusion

posted by Jason Kottke   Jul 31, 2017

This impossible M.C. Escher-esque cube broke my brain a little bit. And you might get some ASMR tingles when the cube snaps back into place right at the end. Mmmmmm.

Roses are red, violets are insane…

posted by Jason Kottke   May 03, 2017

Pluses Optical Illusion

…this optical illusion broke my brain. And then for a second, I was like, I got it. Then my brain broke again. Repeat for several minutes. (via bb)

Update: This illusion was made by Charlie Deck. (via @tdhooper)

Is this ham blurry or in focus?

posted by Jason Kottke   Jan 06, 2017

Blurry Ham

Is this a blurry photo of some sliced ham? Or is the ham perfectly in focus? This is a gnarly optical illusion, that’s for sure. Even when I force myself to realize the photo is in focus, that ham still looks blurry. (via digg)

The Ambiguous Cylinder optical illusion

posted by Jason Kottke   Jul 01, 2016

I couldn’t figure this out when I watched it on my phone this morning, but if you watch it in fullscreen HD, you can see how the shapes are cut to look different from various angles. Still trippy though.

Update: Make Anything reverse-engineered the illusion…here’s how it works:

(via @dunstan)

Trippy spinning optical illusion

posted by Jason Kottke   Feb 01, 2016

Spinning Optical Illusion

Somehow, this woman seems to be spinning both clockwise and counter-clockwise simultaneously. This is worse than the spinning ballerina. Anyone know who did this? Randomly found it on Facebook and couldn’t trace the source back…

Freaky optical illusion

posted by Jason Kottke   Dec 06, 2013

Which gray block is actually darker? Hold something over the seam to find out.

Optical Illusion Blocks

Mindblowing, right? Now for the fun science part: how does this effect work? Well, it works because whoever made this thing is a fucking witch. I mean, Jesus. QED. (via ★interesting-links)

Freaky realistic optical illusions

posted by Jason Kottke   Nov 28, 2012

When the hand reached in to turn the Rubik’s Cube, my brain melted and spilled out of my ear and into a puddle on the floor.

The images used in the video are available for printing out so that you can wig out your friends and kids in person: Rubik’s Cube, tape, and shoe. (via colossal)

Blue and green optical illusion

posted by Jason Kottke   Jul 06, 2009

This amazing optical illusion was everywhere last week, but if you didn’t see it, you should check it out.

Ames’ Window

posted by Jason Kottke   Jun 09, 2009

This is one of the freakiest optical illusions I’ve ever seen.

(thx, veronica)

Optical illusion shoes

posted by Jason Kottke   Jun 04, 2009

It took me at least 30 seconds of looking at these shoes to realize that the woman wasn’t floating two inches off the ground and what I thought were shadows are actually heels. Even knowing the secret, the effect switches for me like a Necker cube or the spinning dancer.

Like a pirate

posted by Jason Kottke   May 20, 2008

Here’s a fun optical/muscular illusion to try out:

This morning I went into the darkest room in our house (the kids’ bathroom), closed the door, and turned off the lights for 5 minutes. There was enough light coming in through the crack in the door that after a minute or two I could begin to make out shapes in the room: A towel rack, the shower curtain. My eyes had adapted to the dark condition. Then I closed my right eye and covered it with my hand. I turned the lights back on, for a minute, until my left eye had adapted to the light. Then I turned the lights off.

I could still see the towel rack and shower curtain with my right eye, which remained adapted to darkness. But my left eye could see nothing. In fact, my left eye felt as if it was closed. I made every effort to open the eye, but it seemed that some unstoppable force was keeping it closed. The only way to make my eye feel as if it was open was to cover it with my hand. I still couldn’t see anything with the eye, but at least I could convince myself it was open.

Spinning dance optical illusion

posted by Jason Kottke   Oct 11, 2007

I’ve been obsessing over this optical illusion ever since I ran across it yesterday.

Spinner

Is she spinning clockwise or counterclockwise? Or both…and how is that even possible? It’s a left-brain vs. right-brain test…which way she spins for you determines which side of your brain is more dominant. (Tip: if you’re having trouble getting her to switch directions, focus on a point a couple of inches below her feet…that seems to do it for me.)

Update: Neuralogica Blog debunked the left/right-brain explanation in this post.

This news article, like many others, ignores the true source of this optical illusion and instead claims it is a quick test to see if you use more of your right brain or left brain. This is utter nonsense, but the “right-brain/left brain” thing is in the public consciousness and won’t be going away anytime soon. Sure, we have two hemispheres that operate fine independently and have different abilities, but they are massively interconnected and work together as a seamless whole (providing you have never had surgery to cut your corpus callosum).

(via @danielpunkass)