I've acquired a new superpower

>Probably my peak fame right there.

My son and I always make jokes about everyone's 5 minutes of fame. Some random person on the jumbotron at a sporting event "Yup, there's his moment, it's over now."

At least yours got you something ;)

I can't overlap the images to save my life - they get like halfway there and that's it...

Failed to perform the technique despite multiple retries, but didn't have any issues spotting differences the normal way for all except the impossible mode - which just felt like it would be tedious.

My usual method is just to brute-force linear scan from left to right, top-to-bottom. May not be elegant, but it works.

Just got a funny visual of someone going crosseyed and focused on overcoming a challenge in front of them, with a crowd of people cheering them on.

Sadly I was never able to gain anything from this trick other than my kids admiration. Often times kids menus at restaurants will have a spot the difference and I can see everything instantly doing this. Impressive to a kid but this girl in the video was obviously doing the same thing and does not impress me.

This is my peak fame as well. I had the high score on every one of these I've played using this method. My friends were always try to figure out how we could make money doing it...

The game is usually called 'Photo Hunt'

I was about to post this same exact post :)

Was the high score holder on there for a few years.

Now try it with various colors, some people can see "impossible" colors [0].

[0] https://preview.redd.it/yaiyf2bi9aa31.png?width=640&auto=web...

I wrote a paper about doing this using human eyes as the "repeating pattern" (either someone else's, or your own in a mirror): https://philpapers.org/archive/ALEDSK.pdf ...You can use this trick to make boring meetings or conversations mildly more amusing (but be careful not to look like a clown crossing your eyes).

If you're an expert at this, you can even do it to your own hands. Hold both hands in front of you but with one of them palm-away and one of them palm-toward you, so that they have the same shape, then cross- or parallel-view them to get an illusionary middle third hand. Walk around while focusing on the third hand and it's a seriously trippy effect.

Another "super power" application similar to OP: the ability to confirm whether or not two distant digital clocks' seconds-digits are perfectly in sync. Since they're distant, it takes time to shift one's gaze from one to the other, making it hard to confirm whether they're in sync. But cross your eyes so as to reduce the distance, and voila.

Yet another application: quickly assume the same head-tilt angle as your conversation partner. Suppose they tilt their head to the left by N degrees and you want to tilt yours the same way, how can you be sure you have the exact correct tilt? Easy: parallel-view their eyes (as described in the aforementioned paper). You will HAVE to tilt your head the same as them in order to see their "third eye" (and once you've locked on to their third eye, you can effortlessly adjust your head tilt as they do by using their third eye as the necessary guide)

When I read about Gauss basically inventing Arithmetic Progression at seven years old it gives me similar vibes. What led him to see a different way in adding the numbers 1 to 100? Surely he could have visualized it on his own in an abstract manner, but I tend to wonder if he had a similar enlightening experience like yours.

Yep, this is exactly what came to mind with this "newly unlocked superpower".

I wonder if OP is aware they made a joke about the inability to use this superpower to identify a sailboat in a 90s indie movie.

Wow I feel like I've never seen anyone talk about this. Doing it with fences can feel pretty magical, like the object is more "real" than other things.

I can never do it. Always find it amusing when another kid knows how to do it.

I'll second the blink comparator method as a simple diff checker, or when comparing two chunks of code that are structured exactly the same way but somehow behave differently. (e.g. "what's the difference between these two functions" or "how is this yaml block different from that yaml block"?)

Line them up as two tabs in the editor, flip very rapidly between the two repeatedly, and usually the difference is apparent in 5-6 flips.

To reduce eye strain, don’t cross your eyes, but relax them (so, the other way). Instantly clear and snaps together as if magnetic.

A blink comparator would be a much better GUI tool for comparing photos (for example original vs. post-processed) than the standard "left half-right half" with a movable divider. Alas, it’s rarely used (eg. Lightroom’s compare view doesn’t have one).

Fun fact: it's a different device, but the principle is the same as the device used in the documentary Tim's Vermeer. It results in the images overlapping between your left and right eye and you simply paint until the difference goes away.

As a kid, I got a Magic Eye book and learned to see it by crossing my eyes (ie, focusing in front of the screen). I thought it was pretty interesting when I realized that I was seeing all the images inverted ("peaks" were "valleys" and vice versa) due to the way I was focusing. Alas, I never was able to see the images "correctly".

Yup, I loved Magic Eyes as a kid. This was easy.

Nevertheless, I was astonished that "impossible mode" literally took me only 1-2 seconds to find the missing star.

Like, I knew our vision is good at interpreting depth from images. I figured it would be all right at finding large areas of differences. I had no idea a single freaking pixel could stand out like a sore thumb.

Maybe we are the opposite. As a kid, I could only do cross-eyed-focus-in-front-of-screen, but not "focus beyond the screen". Or a book at the time.

So I was able to see the 3D in Magic Eyes, but the 3D effect was inverted.

Today as an adult I am able to focus beyond the screen, but it's still much easier for me to do it cross-eyed.

I also got all the images in the post almost right away. But my eyeballs focused in front instead > _ <

I have a slightly lazy right eye, so this has always come naturally to me, but I will say it's considerably easier to achieve the false focal lock on printed material— something about screens, even quality ones with high refresh rates, just isn't the same.

How do you do this focusing beyond the screen!?

I'm trying so hard to make this happen. Stare really far in the distance and then move the image in front of my face on my phone. No matter the distance between my face and my phone i can't overlap the images.

Focus in front of the screen is the easy one. How do you get beyond....

I'm great at magic eyes / stereograms and have a ton of posters around my house with them, but I still had trouble with seeing the differences in the test images. I easily locked in my focus on the overlapping cat images but only one difference stood out to me. I eventually got them all but it wasn't that easy (maybe with practice I could get there). The differences are noticeable when I focus right on it, but when I'm looking at the whole image it's harder to tell what is missing from one eye.

I can get the images to merge but the differences don't stand out.

I can do magic eyes, but this technique doesn't work for me. My left eye is dominant enough that the whole image just looks like what my left eye is seeing.

No need for the Mac Plus program, you can make these in any text editor. Use a fixed-width font and fill a line with a repeating word eg

WORDWORDWORDWORDWORDWORDWORDWORDWORDWORDWORDWORDWORD

Then copy that and paste it a bunch of times to make it multi-line.

Cross your eyes so that the WORD's overlap (all except the leftmost and rightmost). You now see two cursors instead of one. Position your two cursors anywhere you want and then insert a space in order to make the corresponding WORD (or ORDW or RDWO or ORDW) sink into the screen. (Or rise if you parallel-view.)

We used to do this in the computer labs back in 6th grade.

This happens to me easily inside cars with these dotted-breathing roof interior patterns. (Edit: g “perforated vinyl fabric”)

Well, worse than easily - sometimes I cannot get back to normal and am not sure how far it actually is, because the nature of the pattern allows to re-lock at every few cm. I just don’t know where I’m really looking at unless there’s an irregular object nearby.

This happens to me too. Particularly when it's on a narrow horizontal repetition (like wooden slats on a wall).

I attribute mine to playing a lot of the game Magic Carpet from the mid to late 90's. It had some interesting graphics modes, including Red/Blue anaglyph 3D and a stereogram 3D mode. It was fun to try to play it, but it used noise for the pattern, so you didn't get textures, only blobby shapes.

I find that there are different techniques to seeing both.

If I stare at the image and cross my eyes until focus lock I get crossview where the image goes back into the page.

If I bring the image right up to my eyes and stare through it into the distance, then slowly move the image backwards into my gaze until I get focus lock, then I get parallel view where the image pops out of the page.

I have always wondered the difference between the two and why it happens. Thanks for shedding some light on it :)

EDIT: I have just managed to achieve both without moving my head or the image for the first time in my life! Just by trying to look further 'past' the picture into the distance, and then by slightly crossing my eyes and focussing at a point in front of the picture.

I have been trying to do this for 30 years, and it is only your explanation which helped me to do it. Thanks so much!

Cannot figure out what is the difference. I can focus on both seemingly without changing anything, even though they aren't both in focus at the same time. But I don't know what I'm doing differently, I just move my eyes up or down, adjust a bit, and that's it.

Note that for parallel viewing the left edges (or centers) of the images should not be farther apart than your own eye spacing aka interpupillary distance (IPD) sometimes just called PD.

That imgur may need to be shrunk depending on your screen for parallel to work.

I can do both pretty comfortably, but there’s a definite bias to parallel, way easier for me.

Here are some tips;

1. When you cross your eyes, gradually let them return to uncrossed. Try to do it as slow as possible. Along the way, try to line up any structures that you see in the image that are repeated from left/right half.

2. Once you are able to hold a cross-eyed gaze long enough with lined up left/right half, slowly move your eyes between different features near the middle. Your eyes will naturally want to start to focus and match up pieces.

3. Don't be too far or too close to the image; they are usually easily viewed from comfortable distances. If the image is too big, make it smaller. It's usually easier smaller.

4. Initially, when you cross your eyes, or look through the image, it will likely be blurry. This is because your brain naturally associates accomodation and convergence with also changing focus. You'll learn to decouple those things and you will more quickly be able to go from focusing on the 2D image to crossing it without changing focus much.

There's a whole bunch on this site: https://www.magiceye.com/stwkdisp.htm

Same here, but I always imagined that for it to work, I would need to have roughly equal vision in both eyes, which I don't. Everything is blurry with my left eye, and no glasses or lenses have ever helped. I attribute this as the reason.

I've also always had a hard time with these. I suspect it's because one of my eyes was slightly lazy when I was a child, so my brain learned to put more importance on the signal from the other eye. When I cross my eyes, the image from the better eye tends to just totally override the other one, so it can be really hard to see these kinds of effects.

I just spent 30 minutes trying to get any of these examples to work before it clicked.

What worked for me: I’m not “crossing my eyes.” Trying to cross my eyes precisely enough to get the two images to overlap was impossible.

Instead I’m starting by crossing my eyes until a third out of focus image starts to appear between the other two images, then I immediately abandon trying to cross my eyes and instead focus on bringing that third image into focus like it’s “floating” in the room at a different point in space than the page its on.

Apparently the circuits in my brain and eyes are good at this. As soon as I can get the “third image” to show up by crossing my eyes, I can “look” at it and my eyes snap perfectly into position.

After about 5 minutes of practicing I can focus on the third image in about a second from the time I begin to cross my eyes.

On the third image, the differences between the two images “shimmer” like a holographic foil on a playing card.

Doesn't work for me either. I just made myself queasy while trying to cross my eyes for ten minutes haha

This is really cool! it allows you to see 2D charts in 3D without actually rendering anything in 3D

Incredible!

My odd claim to fame which is hard to garner praise for is that when I was a kid I always followed a certain pattern when I did something on a left or right foot. I always tried to even it out. So if I pinched my left toes, then I would do my right. But then I would undo that by going right then left. And then I would undo that by undoing the entire thing: right left left right. And the pattern went on:

LRRLRLLRRLLRLRRL…

and so on. It seemed easy enough to remember because you would just undo what you did last.

A few decades later and I learn that’s the Thue Morse word (1) which has many interesting properties like being overlap free. Unfortunately it didn’t give me any kind of advantage when studying combinatorics on words. Just a weird “wait… where have I seen this before?” moment.

[1] https://en.wikipedia.org/wiki/Thue%E2%80%93Morse_sequence

> When your belt buckle hangs a little loosely on the front of your pants. You can hook the buckle's prong onto the front button of your pants and it'll stay put. So many people are excited to learn this.

Yep. And there is a special vertical prong keeper tab on some trousers for exactly this purpose.

For when you feel a sneeze coming on:

- Want to sneeze? Look at a bright light.

- Don't want to sneeze? Scratch your ear.

Ear rumbling: https://www.reddit.com/r/earrumblersassemble/

Eye shaking: https://old.reddit.com/r/Eyeshakers/

Some of us are born with small frenula of the tongue (or we undergo tongue-tie surgery as kids) and can thus perform Khecari mudra without the traditional self-mutilation used by yoga-masters. https://en.wikipedia.org/wiki/Khecar%C4%AB_mudr%C4%81 This can be useful for cleaning tonsil stones or post-nasal drip, but of course you must do so discretely since people would consider that absolutely disgusting

If you want to read out loud for long stretches of time and you hate taking breaks to catch your breath: you can read out loud while inhaling too! (It feels and sounds super weird though so this isn't very useful in practice.)

And here's a party trick related to OP's super power. Pick a distant object and cross your eyes so as to see it double, preferably with the two doubles distant from each other (i.e., cross your eyes significantly). Then, alternately switch between staring at the left double, and the right double. If you do it right, it will look like your eyes are moving in a bizarre alien way.

> I'm frequently surprised by the amount of seemingly ordinary skills I picked up as a bored child that other people didn't. This was an obvious way to solve those "spot the difference" pictures in magazines.

Conversely, I'm amazed by the amount of things I discover as an adult are not common experiences or skills for people, despite being considered as such. This includes, for example, having an inner voice (which I do), or ability to visualize things in your head (which I don't).

Wrt. the latter, when I learned as an adult that some people actually can conjure up images in their mind on demand[0], and conversely that aphantasia is a thing, it took me few more years to connect that back to some early experiences in childhood - being bored out of my mind by some well-known novels that my parents and teachers found particularly engaging. Specifically, the ones rich in descriptions of scenery. They'd say that's the best part, what makes the story rich and immersive, and that's what imagination is for and those books are good for exercising it. Meanwhile, I'd feel ashamed and wonder what the fuck are they talking about, while skimming to find where the descriptions end so I can resume reading from there. Well, it turns out what they said was true for them, but is not true for people like me, who can't visualize to save their life.

Well, except in dreams. Which makes the whole thing even more fascinating.

> Some recent example of things I shared:

Interesting. I somehow managed to never learn either, so thanks! Ironically, I realize now I've probably seen people do the jacket swing trick hundreds of times, and yet it never registered in my mind as a distinct technique, much less one that I could learn.

EDIT:

One such skill I didn't pick up until my wife taught me, and that I know many (most?) people don't know, is how to correctly pour liquids out of rectangular containers with off-centre openings. Think a milk box, or 5L jug, or fuel canister. Turns out, you shouldn't flip them to give the liquid the shortest path to destination, but the opposite - have it flow alongside the entire top edge of the container. This gives you steadier flow, and you'll spill less. I still find it counterintuitive, but it works.

--

[0] - Fun fact: that makes "undressing someone with your eyes" a literal ability for them too.

My eyes seem to immediately refocus as soon as my finger moves away no matter how many times I try this. Before I move my finger away, everything in my peripheral vision is too blurry to be useful.

I've always been able to merge pictures by focusing into the distance, and I thought that's how everyone did it. So I found confusing all the talk of crossing eyes. I tried your instructions and, within 30 seconds, was able to see the cat image by crossing my eyes.

The cross eyed method seems more amenable to different image sizes. With my regular method, I can't merge images if they're too large (unless I step back).

Does this only work on desktop? I am trying this on mobile and the images never overlap. Wondering if maybe my viewport is too smal

For spot-the-difference, crossing your eyes is more effective and easier to "dial in" than uncrossing them. You're essentially making each eye look at the opposite image. If you try uncrossing, then you need to make sure the images are at the exact correct distance to cause them to overlap with that technique, because you can only uncross your eyes enough to look straight ahead.

See my other comment about cross view vs parallel view, looks like you can do one vs the other and the author can do the opposite.

While intuitive, I’m not so sure. I look at the center line and slowly cross my eyes until the 3rd image slides into place and then I get focus lock. At no time do I feel my eyes uncross and go the other way. Hmm!

Both work equally well if you just want to spot differences. Cross-eyed view is somewhat easier to do, since people naturally cross their eyes when looking at something close to their face, but there is no natural reason for one’s eyes to diverge. But cross-eyed view also gives a subjectively smaller image, and is also not the usual way autostereograms are made to be seen.