What Is Your Favourite Optical or Auditory Illusion?

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From Kate's list of suggested topics for discussion; this one is my fave. I'm going to give it some thought and then post, but don't feel like you have to wait for me. Go ahead.

Nick A. (Nick A.), Monday, 28 April 2003 13:23 (seventeen years ago) link

I didn't have much luck with my thread, but this one is mine:


kate, Monday, 28 April 2003 13:25 (seventeen years ago) link

I like the oasis illusion you get when driving down the highway on a warm day and it looks like the road ahead is wet. Similar to another favorite, when you're barbecueing and the heat waves distort everything.

Nick A. (Nick A.), Monday, 28 April 2003 13:27 (seventeen years ago) link

the belvedere

mark s (mark s), Monday, 28 April 2003 13:29 (seventeen years ago) link

Nick A., that's actually the same illusion, yo.

i like the one where you stare at a blob for a minute and then you see god on the wall! apologies for not being able to recreate it here for your amazement.

pete b. (pete b.), Monday, 28 April 2003 13:36 (seventeen years ago) link

THis is the god one:


kate, Monday, 28 April 2003 13:40 (seventeen years ago) link

I like the one where you stare at a green and black American flag for a minute or so, then you close your eyes and it's the good ol' rd wht + blu.

The bendy pencil is good too.

Aaron A., Monday, 28 April 2003 13:42 (seventeen years ago) link

HSA was demonstrating one of his favourite auditory illusion in the little medieval alleys in Clerkenwell (heh heh that sounds saucy). If you clap your hands in a small enclosed tube like space, you get this really neat sounding metallic reverb which sounds like it is a musical note. Very very cool, except I can't explain it in scientific terms as well as HSA can.

kate, Monday, 28 April 2003 13:44 (seventeen years ago) link

Is stereo an auditory illusion? If so, I like stereo.

Nick A. (Nick A.), Monday, 28 April 2003 13:44 (seventeen years ago) link

Stereo as a concept? Don't think so.

Stereo placement... yes. Illusion. Also very cool.

kate, Monday, 28 April 2003 13:47 (seventeen years ago) link

The one where you point two figners at each other horizontally, then you bring them closer and closer to your eyes and it looks like there's a mini-finger floating in between the two. That is ace.

William Bloody Swygart (mrswygart), Monday, 28 April 2003 13:50 (seventeen years ago) link

More Escher


from the official M C Escher site, for that authentic '70s student decor flashback

chris j (chris j), Monday, 28 April 2003 14:04 (seventeen years ago) link

Thinking your train is moving when the one on the next platform is pulling out. I love that...

Simeon (Simeon), Monday, 28 April 2003 14:32 (seventeen years ago) link

Brocken spectre:




Alfie (Alfie), Monday, 28 April 2003 14:43 (seventeen years ago) link

Oh yeah, Simeon, that's a good one.

Nick A. (Nick A.), Monday, 28 April 2003 14:51 (seventeen years ago) link

Neither optical nor auditory, but similar to the my-train-isn't-actually-moving-it's-the-other-one sensation... When you're driving an automatic after driving a manual for a long time, and you apply the brake, and press down on the (non-existant) clutch at the same time, only the engine doesn't disengage, and you catch yourself leaning backward into your chair because your body expects to be pulled forward, but isn't.

Anyone know what I'm talking about? Hard to splain I guess... Anyway, I love that one for some reason.

Colin Saunders (csaunders), Monday, 28 April 2003 23:37 (seventeen years ago) link

when you look at a steep sided island across a flat sea on a hot day and it looks as though the island is floating just above the water.

isadora (isadora), Monday, 28 April 2003 23:52 (seventeen years ago) link

The checker shadow illusion is my favorite. It still makes my brain explode.


Chris Barrus (Chris Barrus), Tuesday, 29 April 2003 00:40 (seventeen years ago) link

These are so not helpful when one has a dose of the spinnies.

Saskia, Tuesday, 29 April 2003 01:47 (seventeen years ago) link

My favourites are all Bridget Riley's B&W op paintings. I love them, but can't bear looking at them for more than a few seconds.

Martin Skidmore (Martin Skidmore), Tuesday, 29 April 2003 11:49 (seventeen years ago) link

If you stare at Chris B's moving version long enough, you do actually see it. And then Square B looks unnatural and out of place and lighter than the other white squares in the shadow. Wow.

kate, Tuesday, 29 April 2003 12:06 (seventeen years ago) link

It doesn't do that for me - i can follow the square moving across but then it kind of flips back to being a lighter shade. it's weird! i like the one kate posted a lot too.

liz (lizg), Tuesday, 29 April 2003 14:16 (seventeen years ago) link

two months pass...
My favourite auditory illusion is the Shepard scale. It creates the illusion of an infinitely rising scale.

fletrejet, Friday, 11 July 2003 02:40 (seventeen years ago) link

The classic


Mr. Diamond (diamond), Friday, 11 July 2003 03:02 (seventeen years ago) link

I've developped a fondness for "LOW high LOW high LOW high" myself.

Funny that this thread got revived now, HSA and I were talking about this last night. We have a wire-framed table that he was trying to turn into a Necker cube because I argued with his evaluation of EVP.

You know, any other couple would just argue about dishes or something.

kate (kate), Friday, 11 July 2003 08:25 (seventeen years ago) link

four months pass...
I like this one. I don't know if it's my favorite. Recently I have had to explain how you find the old lady to my friends about four or five times.


Aja (aja), Sunday, 30 November 2003 16:11 (sixteen years ago) link

fifteen years pass...

Rabbits love getting stroked on their nose pic.twitter.com/aYOZGAY6kP

— Dan Quintana (@dsquintana) August 18, 2019

Fuck the NRA (ulysses), Monday, 26 August 2019 16:51 (ten months ago) link

I get that it looks a bit like a rabbit (see Wittgenstein's duckrabbit), but surely nobody actually *believed* it was a rabbit? It's very clearly not.

emil.y, Monday, 26 August 2019 16:59 (ten months ago) link

yah, it's not meant to be truly convincing, more of an actualization of the paper image.
this thread could use more of a workout

Fuck the NRA (ulysses), Monday, 26 August 2019 17:01 (ten months ago) link

Shepard tones rule. I want to actually visit an Ames room one day and see what it's like irl and not just in photos.

emil.y, Monday, 26 August 2019 17:05 (ten months ago) link

just leaving this here: https://www.illusionsindex.org/illusions

Fuck the NRA (ulysses), Monday, 26 August 2019 17:22 (ten months ago) link

the looking at a fan and making it go backwards shit

flappy bird, Monday, 26 August 2019 17:37 (ten months ago) link

three months pass...

^ this shit works!

Fuck the NRA (ulysses), Monday, 16 December 2019 20:39 (six months ago) link

would work even better if he gave us longer to look at the dots in between all the captions :)

éminence rose et jaune (Noodle Vague), Monday, 16 December 2019 21:54 (six months ago) link

here's a looping gif:


Peaceful Warrior I Poser (Karl Malone), Monday, 16 December 2019 22:11 (six months ago) link

weird, it completely does not work for me.

mick signals, Monday, 16 December 2019 23:20 (six months ago) link

my version doesn't work quite as well as the video, i shouldn't have posted it!

Peaceful Warrior I Poser (Karl Malone), Monday, 16 December 2019 23:29 (six months ago) link

if you can only see red/green dots moving down, try focusing on the top edge of the image... it reliably kicks me into seeing the left/right yellow dots

the girl from spirea x (f. hazel), Monday, 16 December 2019 23:33 (six months ago) link

No the gif works fine Karl and you can stare at it uninterrupted

éminence rose et jaune (Noodle Vague), Monday, 16 December 2019 23:50 (six months ago) link

it's... not quite right? there's a few frames missing i think. still works tho.

Fuck the NRA (ulysses), Tuesday, 17 December 2019 03:21 (six months ago) link

Always my favourite. This is not a moving image:

an incoherent crustacean (MatthewK), Tuesday, 17 December 2019 03:30 (six months ago) link

With the dots, I can see them moving up/down, or I can see them moving left/right, but they're always red/green. Nary a yellow dot.

MatthewK's checker snakes are pinwheeling inexorably just like they should..

mick signals, Tuesday, 17 December 2019 03:55 (six months ago) link

Did I already answer this? I love barberpole tones. Underused imo

El Tomboto, Tuesday, 17 December 2019 04:03 (six months ago) link

The “Adelson's Checker-Shadow Illusion” in Fuck the NRA’s link upthread is my favorite.

Mr. Snrub, Tuesday, 17 December 2019 14:31 (six months ago) link

red/green dots is a bit of a cheat - if you follow a single dot going down it stays red or green, if you follow one going across it changes between red and green quickly enough to be perceived as yellow. doesn't feel like there's any brain hacking or uncovering secrets of how perception works.

The Pingularity (ledge), Tuesday, 17 December 2019 14:41 (six months ago) link

I first became aware of the Shepard Tone when some scientist chose it as one of his records on Desert Island Discs years ago. Imagine, you can pick just seven pieces of music, and that's one of your choices. Bloody boffins.

fetter, Thursday, 19 December 2019 11:52 (six months ago) link

This guy: https://www.bbc.co.uk/programmes/p0093x2r

fetter, Thursday, 19 December 2019 11:52 (six months ago) link

one month passes...

Thats really breaking my mind

Fuck the NRA (ulysses), Sunday, 19 January 2020 05:23 (five months ago) link

five months pass...

there are 16 circles in this picture pic.twitter.com/FSKci9034D

— j.d. (@jiveDurkey) June 30, 2020

time is running out to pitch in $5 (Karl Malone), Tuesday, 30 June 2020 05:45 (one week ago) link

oh damn, that's some magic eye shit

Fuck the NRA (ulysses), Tuesday, 30 June 2020 05:47 (one week ago) link

Do hallucinations count? For about a year I was having hypnagogic auditory hallucinations (reverse sleep paralysis - being partially asleep instead of awake) regularly, once I figured out I wasn't going crazy I started to enjoy them.

Donald Trump Also Sucks, Of Course (milo z), Tuesday, 30 June 2020 05:54 (one week ago) link

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