I've acquired a new superpower
danielwirtz.com
danielwirtz.com
One of the games was a "spot the differences" between two pictures with an ever decreasing timer for each round. Using this trick I was able to easily surpass the high score, and garner a crowd watching me perform this mind numbing feat.
Probably my peak fame right there.
Looking far away may be harder, and afaik it’s near impossible to look “past infinity”, iow pictures must be less wide than the distance between your eyes.
Btw these two methods aren’t equivalent in watching stereograms. If you look at one and see something but it doesn’t really make sense, then it’s probably the opposite chirality.
Personally I hate the crossing method because it makes your eyes feel strange for a while.
then for the stereogram you do the same, observe the out of focus edges of the left and right pictures, then slowly uncross until left and right image occupy the same spot as though they were the same object. now its out of focus, but one (ok, actually three, because there were two, you “doubled” that by crossing, then merged two of them. but ignore the other two and focus on the merged pair)
sometimes you will merge images of the same picture, in this case you are just back at your normal vision, repeat :)
then you try to keep them overlapped and focus the vision, try to “believe” that you are really looking at a single object.
I used to not be able to do the "magic eye" 3d images until recently, and this trick is pretty handy.
Diverging requires you to look past the image, meaning you have nothing to really look at, which makes it difficult to figure out what your eyes are even supposed to do.
Those stereograms aren't helping much either, since they look like nothing until you get it right. With cross-eye you have instant double-vision that you just need to align.
Cross-eye also works across much larger distances, diverging fails when the images are too far apart.
https://triaxes.com/docs/3DTheory-en/522ParallelCrosseyedvie...
which some people struggle with, somebody posted a
https://en.wikipedia.org/wiki/Autostereogram
to HN yesterday which some people get and others don't. (That's different from the "cross-eyed stereogram" because one of them involves having two images and the other one has one image with two images hidden in it)
In these later examples (starting with the easy puzzle of the OP, and your 3d examples), I find that I do the process in two stages.
Unfocus my sight until the third image shows up in the middle at the correct size (as a blurry mess). Then try to focus the center image.
which is one reason why stereo movies have struggled. (That plus some people get sick... Having both a flat and 3-d movie in two different theaters comes across as money grubbing to the consumer but it is really a money sink to the theater.)
You can also tell if your head's level, just by crossing your eyes. If the two images are diagonal to each other, then your eyes/head aren't level. I have no idea what the possible use for that would be.
It makes me wonder if the wall-eyed version could be useful for eye health.
I've often heard when doing computer work, you should focus on something 20 meters away for 20 seconds, every 20 minutes.
Doing a wall-eyed magic eye seems like the same thing physically, your focal point is much further away.
Would be cool to have some software that lets you overlap two coding windows, so you have a 3d terminal.
Which is why for ASGs people advise you to look past the picture. Or why you bring the pic close to your eyes (so close that you basically have no choice but to look beyond the picture)
Also, if you're doing it on a piece of paper, hold a pen in each hand spaced right so you see the middle (3rd) hand in the middle combined image, and move both hands in sync to circle all the differences. Kind of a cool way to point them out to someone else.
The difficult puzzle took me about 10 seconds here since I was looking for more than one difference. I saw the first difference in about 1 second.
Put the pair of images in front of your eyes.
Bring your finger between your face and the image.
Now look at your finger.
Move your finger back and forth.
While doing this, notice that at a particular distance, the images in background will perfectly overlap each other.
That's your moment.
Pull out your finger and look at that image.
---
Should take lot less tries to learn doing it without finger. I have taught cross eye to my siblings and cousins using this method. But if you always need finger to focus it's fine.
Optician used to tell me to work the muscle by following my finger to my nose, trying to maintain a single image. At a certain point it will snap into two - the 'lazy' eye has given up and drifted slightly - the goal is to get the finger as close as possible. Obviously if you get very close or all the way, that's 'cross-eyed', but I just can't do it.
Here is what worked for me. I used my laptop, zoomed in a bit on the images and brought the screen fairly close to my face. I ensured that the image was crisp using each eye (I also have astigmatism, and I probably also need reading glasses, but there is a sweet spot where both eyes have good focus, and I ensured I was there.) While crossing my eyes a bit, I start to see a third image in the center of the two images, but it's either out of focus (like two overlapping images), or it's very thin, like it's not the full image. I relax and keep my attention on this imperfect image and try to focus on it without trying too hard. Using this approach the image suddenly comes into focus and I no longer have to try to keep it there.
I feel like the key might be to notice the very beginning of the desired image in the center and then to try and focus on it, but in a bit of a relaxed way.
Incidentally when it works it is extremely weird! The other images essentially disappear and it's like you've travelled to another dimension.
I have otherwise good vision, I can read small text from farther than most people (I didn't realize not everyone could read all the small letters on an eye test), I don't have a problem seeing things up close either, etc. but I lack the ability to properly cross my eyes for some reason.
It's too bad because I've spent a decent amount of time at bars with those spot the difference machines lol
Zoom the images in front of your eyes so that they are little less than same width as your eyes.
Try to look behind/beyond the image, as in let your eyes loose/relax. Don't stare at the images instead see in that direction as if you are day dreaming.
Images will overlap at one point. If they don't completely perfectly overlap, reduce the zoom.
Once they overlap, focus the overlapped image.
---
Method 2: Use kitchen towel rolls
After putting those images in front of you, make a binocular out of used kitchen rolls.
Point each roll to each image.
There you go.
I think the "cross eyed" phrase is a bit ambiguous.
What I ended up with (I think) is a focal point not closer than the screen but farther than it. My eyes didn't want to do it at first but then they did.
What is weird about it is the focusing and focal point are out of sync --- my brain can do it but the weird feeling is one of "gosh, this thing is a lot closer than it should be" where "should be" is based on focal point, and "is a lot closer" is based on focus.
Don't want to do this too much, feels like I could easily decalibrate my brain for real life lol.
For most people, having the images resolve in front of the plane of the page such that in resolved overlaid image the right eye sees the left image, and the left eye sees the right image, will work ... and it can work even if the images are farther apart than the interpupillary distance.
Are the eyes mechanically capable of pointing outward (so the interpupillary distance is not longer a constraint)? If so, is the problem then neurological not mechanical (brain doesn't want to send signal so they do that)?
Try that.
Hold the rolls like binoculars where right roll is pointing at right image and left is at left image.
It's like a DIY VR headset where your brain/eyes only gets two same looking things to focus. No outside noise.
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 ;)
Unfortunately, in the next game I made them watch the credits[1] for my son's name in Production Babies. It is right at the end and the wait was embarrassingly long.
[0] https://www.mobygames.com/game/75645/need-for-speed/credits/... [1] https://www.mobygames.com/game/98129/need-for-speed-payback/...
The guy famously trained for months for the fight scene and a tired Harrison Ford just pulled out the gun and shot him. Everybody thought it was hilarious and that became the scene.
https://screenrant.com/indiana-jones-swordsman-shoot-raiders...
"It sounds wrong to say one should thank Ford’s sickness for one of the most iconic scenes, but Raiders of the Lost Ark is definitely better off for it."
https://screenrant.com/indiana-jones-raiders-lost-ark-gun-kn...
"A much more elaborate fight scene was planned, but Ford developed dysentery while filming in Morocco..."
Anyway, over the last couple of decades as an adult, besides realizing the obvious - how terribly shallow that is, and missing so much of what's really good in life - I've realized how fleeting fame seems to be even for the truly famous. Even looking over the list of US Presidents (never mind lesser political figures like VPs, cabinet members, congressmen, etc.) as someone who has always been interested in history, I look at some names and think, "who?" or "I've heard the name, but know nothing about him." I mean, of course you can still read about them, but that even a US President can be largely forgotten as a household name within 250 years is really a stunning thing to think about; they are ultimately no more immortal than someone who only has their name in a genealogy database or on a grave marker.
> He was the man most gracious and fair-minded, > Kindest to his people and keenest to win fame.
Those are the last lines of Beowulf. A man who won great fame among his people by slaying monsters and dragons. It's telling that the final line of the poem ends with his most dominant trait, "and keenest to win fame." Wanting fame is not wrong, and is far from shallow. The question is, "fame for what?" Regardless of whether you think Beowulf existed or not, it's telling that for a whole culture that the most important characteristic of a great man in one of their great poemsis "keenness to win fame," almost as a wink, with the bard saying "and if you want to be sung like this hero, you must desire fame just as keenly, and so do great deeds."
This may be something I'm making up, but I have the feeling that the fame = immortality concept came out of legacy: people wanting to create a family that continues on after themselves (and is rich, powerful, etc). Which makes sense, because then we're talking about a logical extension of the reproductive instinct. But in the modern world even that seems unreachable to me: we're so utterly different from our grandparents that we might as well be aliens, and the same will probably hold true for our own grandchildren.
I guess all that puts me in the Mike Tyson school of thought on legacy: "We're just dead. We're dust. We're absolutely nothing."
> we remember factoids... I might remember 7 things about Teddy Roosevelt... but those things do nothing to represent the complex individual he actually was.
I've thought this before when looking at Wikipedia pages. Especially for less famous people with thin pages, they'll cite just a handful of news articles or press releases in which the person appeared. If there were a page like that for me, or the people that I know best, the collection of factoids would be a laughably inaccurate reflection of who we really are. Someone told me that it's important to write an autobiography for this reason.
Another is that which is kind of intangible and describes the person(again not personal details but what they think about the self and ideas), like an autobiography, but still is very hard to get at: it's like they say Being in someones shoes.
It's impossible to understand both of the above kinds of thoughts, in general, because conscious thought is utterly temporary and highly subjective. And more so for the second kind of thought above for most people it is true that, their complex self is meaningless to others.
It's likely why you mentioned you feel disassociated from what your parents/grandparents thought.
https://nation.africa/kenya/blogs-opinion/blogs/dot9/ndemo/t...
Humanity will not forget Newton, Einstein, Shannon and Crick. And up to a point, trying to do what they did, discover new things about the universe is not an unhealthy goal.
So when another colonizer comes up, we will have newer people associated with these. Hope it does not happen. But history does say so.
Newton, Leibniz; Einstein, Lorenz and Riemann; Shannon, Kolmogorov; Crick, Franklin.
When the context is, to quote the parent comment:
> I look at some names and think, "who?" or "I've heard the name, but know nothing about him." I mean, of course you can still read about them, but that even a US President can be largely forgotten as a household name within 250 years is really a stunning thing to think about
I suspect only Newton and Einstein are even household names. I'd be very surprised if the average person has heard of even one of Lorenz, Riemann, Shannon, Kolmogorov, or Crick, even today, and my guess is that Franklin would probably be assumed to be an associate of either Roosevelt or Benjamin, given the widely claimed but inconsistently cited survey that 12% of Americans think Joan of Arc was Noah's wife.
And Crick's other famous research associate was Watson; I wonder how many times people got him mixed up with the fictional character, or briefly for the IBM computer.
Regarding Shannon, I've read one of his biographies (A Mind at Play), but outside of my circle of friends with CS degrees I don't think anyone I know would know his name.
However, I remember someone who went to MIT observing the same thing about the names of the great scientists and philosophers etched onto the buildings. He noted that he only knew what a few of them did.
Even if you are remembered briefly, what’s remembered isn’t you it’s just some vague representation of you that will fade over time.
Some famous Roman emperor might have said something similar 2000 years ago for all I know but I forget his name. :P
And yet you might be able to list some Roman Emperors, for good or bad (Cesar, Augustus) or even politicians (Cicero, may e Seneca) after 2000 years.
As an aside, I'm really hoping that Trump doesn't do anything notable enough to somehow be like that. I fear that he might be more driven to do so than any past US President.
Sadly no one saw this 'feet'.
Was the high score holder on there for a few years.
The game is usually called 'Photo Hunt'
My usual method is just to brute-force linear scan from left to right, top-to-bottom. May not be elegant, but it works.
Makes you wonder if the kid he was talking about had a lazy eye or crossed eyes or something.
I, on the other hand, 37 years later,am basically permanently crosseyed from the experience lol. It somehow became a resting state for me from all of the practice, so I’m always doing it on any kind of repetitive patterns, and even “successfully” on random ones which does some really weird stuff in your visual cortex.
As it happens, I also can't focus on the images in TFA after crossing my eyes to get the shimmer the author refers to.
In my recent years I have developed some astigmatism, but I can still do them without difficulty.
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)
Stereogramming your colleagues eyes during boring meetings.
Ha
Edit: I accidentally did something similar by imaging the crease on an N95 mask as a smile near their nose. It made them look like ducks and I had to bite my tongue so hard to not laugh. I could not unsee it.
[0] https://preview.redd.it/yaiyf2bi9aa31.png?width=640&auto=web...
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.
However, I feel eye strain from doing it, so I prefer other methods. 99% of the time, I do https://en.wikipedia.org/wiki/Blink_comparator instead, just switching between two images with zero flicker and zero displacement offset. Also with both eyes, it's easier to spot certain kinds of subtle differences like color shifts, JPEG-like compression artifacts, tiny differences in antialiased renderings, etc.
One benefit of the cross-eyed method, though, is that you can difference videos. But the use case for that is rarer than differencing images.
Divergence only worked for me in the cat bear image. For the others, I could see a combined image but I could not see any differences highlighted, even though I knew what to look for.
The only disadvantage to this method is that it seems there is a limit to how wide the middle image can be, i.e., the original images may not completely overlap.
If you do want to cross your eyes but do not know how to do it, do the opposite of the above: try to focus on an imaginary point closer to you than the screen as you look at the images. This method is far more taxing on the eyes though.
I don't follow this part, still. Do you mean computer screen / phone screen behind my finger which I would try to look at?
I can switch between my left and right eye when I concentrate, but I can't see both at once. I can try to rapidly switch from left to right to back, but it takes a lot of effort, and it's never the same image at once?
My right eye is dominant, I can switch to left eye if I focus hard, but I can't merge both or can I?
Edit:
I tried putting a paper between my eyes, so right eye would only see right part and left eye only left, am I supposed to see the whole image at once then combining the inputs from both eyes at the same time? Because I can only see left or right, as if my other eye was closed, even though it's not.
I'm wondering if something is wrong with me.
My brain really prefers to process from only one eye at a time, it seems. I wasn't able to get further than the 2 fingers even after more than a hour of trying. E.g. I wasn't able to duplicate anything on my screen.
Weird that I only now realize this after decades of living. I wonder what impacts has it had on my depth perception etc.
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.
This is with focusing beyond the screen. Focusing in front of the screen is something I am unable to do, and not for want of effort.
Also, your eyes might accidentally do this if looking at tiled patterns, e.g. wallpaper.
Relative image size (e.g. view distance) is important.
[0] https://i0.wp.com/www.magiceye.com/wp-content/uploads/2018/1...
When I first looked at this picture I saw the W pattern and then blinked and suddenly saw the intended pattern.
When you lock on the non-intended ones it feels somehow like a secret/forbidden path you shouldn’t go, like consuming drugs.
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 > _ <
To me, all the differences appeared to be flashing (probably my brain alternates between the pair of images it attempts to "lock in", or something to that effect).
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.
Now, ask me to look at my code again for a couple minutes and it might be tough but it worked :)
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....
What's the beyond?
Try it first with your fingers. Hold up your index fingers pointing straight up in front of the computer screen but in front of your face. Focus on the screen. The fingers should divide into four. Move your fingers until they combine.
If you focus on your fingers you can do the same thing to the screen.
Earlier I was looking out a window and thusly way too far. Now I'm in my bed and its about 3m to the wall and with your instructions it worked great.
It works pretty much the same as you said. Thanks for sticking it out with me!
You are given a list of color names, written in font colors that are incongruous with the written word. E.g. "Red" will be written in a blue font, and "Green" will be written in a yellow font.
You have to say the font color and not the written word.
It's challenging, but it's yet another application where going cross-eyed confers an advantage.
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.
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.
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.
Basically, it determines whether the 3D view you're seeing from the stereoscopic pair is convex (pops out of the page) or concave (goes into the page). It is of course possible to learn both views but most people naturally see one or the other. You can go to r/crossview or r/parallelview depending on which one you see.
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!
That imgur may need to be shrunk depending on your screen for parallel to work.
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
So, how exactly is that supposed to work?
I can manage some de-focusing which makes me see 4 images rather than two. Is that part of it? Otherwise, I don't get it.
Now I can do it without the finger.
that's the issue! like an OP i never was able to "converge" the images. for me it is phisically impossible: they are too far apart and never come closer. maybe because i have an astigmatism.
I tried putting folded paper between my eyes to divide the images in such a way that I would only see left side with my left eye, and right side with my right, and I can alternate between image from left and image from right, but I can never see the image at once, or right side when I'm using my left eye.
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.
I wonder what skills other people picked up that I didn't.
Some recent example of things I shared:
+ 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.
+ Putting a jacket or any open-front garment on quickly. I saw someone struggling to maneuver their second arm in a tight jacket behind their back. I explained that if they hold their jacket out in front of them, put their hands in the arm holds, and slide their arm in further as they swing it around their body they'll get it on in a moment. It's also more stylish. They were so surprised.
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.
It's quite difficult.
But, if you let your eyes go out of focus, the ground will suddenly become alive with movement of all sorts of ants bugs and creepy-crawlies.
Yep. And there is a special vertical prong keeper tab on some trousers for exactly this purpose.
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.
I used to be exactly like this - I could not visualize anything. Which was very perplexing for young me - I was astonishingly good at math (winning some country level math competitions even) but could not get past some arbitrary but somehow low level geometry problems. Then it struck me - I could not see the solutions in my head, only on paper, which drastically limited my search space.
But latley after years od doing other thing (including more artsy stuff like drawing) I discovered that I was wrong - its it possible to learn, its just that some people gets this faster and with little effort. For me it was just a other few thousend hours of doing staff that accidentally expanded my visualization ability and then "miracle" happend.
The same was with my supposed tone deafness - guess what, I only believed my self info being tone deaf (real tone deafness is very bery rare). I just was lazy in this departament (in building my ability to perceive tones).
I've always been good at conjuring images in my mind, but I also skip the drawn out visual descriptions.
I could never enjoy Lord of the Rings due to Tolkien's love of describing trees (of the wooden and familial kinds)
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
I'm always reminded that we are all more alike than we realise :)
- Want to sneeze? Look at a bright light.
- Don't want to sneeze? Scratch your ear.
Visual diff. The operation of finding differences between two files by eyeball search. The term optical diff has also been reported, and is sometimes more specifically used for the act of superimposing two nearly identical printouts on one another and holding them up to a light to spot differences. Though this method is poor for detecting omissions in the ‘rear’ file, it can also be used with printouts of graphics, a claim few if any diff programs can make. See diff.
An interesting variant of the vdiff technique usable by anyone who has sufficient control over the parallax of their eyeballs (e.g. those who can easily view random-dot stereograms), is to hold up two paper printouts and go cross-eyed to superimpose them. This invokes deep, fast, built-in image comparison wetware (the same machinery responsible for depth perception) and differences stand out almost immediately. This technique is good for finding edits in graphical images, or for comparing an image with a compressed version to spot artifacts.
Put the images in front of your eyes.
Bring your finger between your face and the image at almost middle of the distance.
Now look at your finger.
Move your finger back and forth and notice the background (where your picture is)
While doing this, notice that at a particular distance, the images in background will perfectly overlap each other.
That's your moment.
Pull out your finger and look at that image.
--
It worked on everyone I have tried to teach. You may always need help of your finger or a tip of a pencil or whatever. But it's lot easier to get those images to merge this way.
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).
This is easy with practice, however IMHO it helps to be significantly nearsighted. Then you simply take off your glasses, and can look at something nearby with infinity focus, which is naturally associated with uncrossed eyes.
I don't know whether it's possible to train yourself to diverge your gaze, i.e. stereoscopically see images that are separated more than your pupil distance. Certainly I can't do that.
When you’ve finished looking at something close to your face and your eyes need to uncross. So you do that eye movement while still holding the image close to your face. Note you are looking “past” where the image is. As long as the image is closer than your infinity focal view you can do this, it doesn’t have to be close to your face necessarily, Magic Eye posters on walls do work.
sudden clicked after fully crossing 5 or 6 times and then relaxing and was able to hold the "3rd image" very easily. felt like magic, even hardest difficulty was obvious
I tried using it, like the author, to visualize and investigate 4D data. But my stone-age brain, regrettably, seems limited to intuiting only 3 dimensions.
You see, I noticed that I have a mouse problem in my garage. I figure if I've seen one mouse, there are probably more. So, I stood on some stairs in my garage and crossed my eyes to sort of blur the scene. It allowed me to catch movement more quickly and I was quickly watching multiple mice run around the edges of the area.
https://www.aao.org/eye-health/tips-prevention/experiment-se...
Apparently, the brain tends to ignore visual stimuli that don't change over a short period of time, which allows you see "around" the blood vessels passing through the middle of your eye. By closing your eye, and moving a penlight around against your eyelid, you can make the vessels cast a shifting shadow on your retina that makes them visible.
The reason you usually see everything out in front of you is that various actions cause your eye to shift about just a little, just enough to cause the image on your retina to shift about enough for the brain to notice.
my vision is so bad with nearsightedness that when I take corrective lenses off, I can focus on an ipad mini screen within 10" of my face and perceptually it is the same as focusing on a distant movie theater screen. No straining, eyes totally relaxed.
With the lights off, it's better than being in a theater. I tried an ipad pro in the Apple store and it felt like I had my own personal unfairly huge IMAX screen.
You can get clever and order a prismatic prescription that bends light out, so your eyes don't have to turn inward. I tried it too, but it gave me nausea.
Similar to the finger moving closer and closer to the upper nose technique, for convergence.
I actually "practiced" a lot like this because I was always amused to notice how we could basically "see through" objects with this double-image thingy (see experiment below).
So I decided to film myself... and I was actually already doing a divergence! Not convergence!
Thanks a lot for your comment which made me realize that.
Experiment:
1. place your phone (handy size/shape for the experiment) in front of one eye (X), at about 20cm.
2. close the other eye (Y) and look at your phone
3. Open Y and look straight without focusing on the phone. By blinking Y, the double-image should appear/disappear, as if it was unveiling what's behind your phone.
4. By closing X and with Y open, looking at your phone, you should see it displaced from where it was when X was open and Y was closed. The size of this displacement is equal to the size of the double-image transparent part.
I even managed "impossible mode" in 2 or 3 seconds.
I’m frequently baffled by how unaware most people seem to be about the absolute basics of how their eyes work. Like, people don’t even seem to be aware of how their stereo perception is largely made from two images, or any of the implications that has. I actively think about the two images maybe dozens of times per day.
Most people at least understand that stereographic vision has something to do with 3D perception because we've all closed 1 eye before.
My eyes get very watery after just a few seconds though, curious to hear from others how common this side-effect is.
(They're saying that the person who send the contract was trying to trick them, and that they were upset when the trick was caught.)
Also, I was using the trick as a "cheat" when I played Tiny Lands on Nintendo Switch, it's a "spot the difference" game, but with 3d landscapes (you can rotate and zoom): https://www.dekudeals.com/items/tiny-lands
Also worth noting there are 2 versions of this kind of cross-eyed focus depending on whether your eyes are focusing on a point in front of or behind the actual image. This determines which side the left and right eye images should go on in the composite. I find it easier to focus on a point in front of the images but IME most examples online are for focusing on a point behind the image.
There were two competing theories:
1. The brain first does a recognition pass (that's a house, that's a person, etc.) and compares the two eyes to see which objects have moved.
2. The brain compares the two eye inputs first, at the "pixel" level and figures out which pattern of pixels has moved, then afterwards, applies recognition to the resulting 3D image.
Magic Eye would only work if #2 is the correct theory (because in Magic Eye, there is nothing to recognize until AFTER you convert to 3D).
https://en.wikipedia.org/wiki/Stereoscopic_rangefinder
https://www.youtube.com/watch?v=cbXyAzGtIX8The effect itself is basically similar to the Magic Eye stereograms (https://en.wikipedia.org/wiki/Magic_Eye) which by themselves are pretty neat; your brain can rapidly detect subtle offsets in random patterns to reconstruct depth cues. In the case of “spot the differences”, the shimmering is due to the irreconcilable disparity between left and right images, which manifests visually as a glaringly obvious “unphysical” apparition - e.g. flickering between the left/right images, or appearing to be out-of-plane with the rest of the picture.
From your POV the images are merged so your hands will look like they're tapping a single image, but from the audience's point of view you look like a savant with multi-attention!
I don't know if it's just my brain working differently or if a there is some confusion in the discussion between crossing your eyes and focusing through an item.
Last year when there was a bunch of fuss about Kate Middleton not having made any public appearances there was a minor flap where people claimed that a photo she'd released was just an edit of an earlier photo.
There was a tweet presenting two photos, one old and one purporting to be new, where she was holding strikingly similar poses. The claim was that the new one was just an edit of the older one. I used this technique and immediately the minor differences stuck out like a sore thumb- her hand was rotated more in one, her hair was laid differently, etc.
Is that what other folks are experiencing also? I see most comments are trying it with their eyes crossed, but what about without?
EDIT: ok I just watched the video. No eyes crossed. For the balloons one I beat out the girl in the video by 2-3 seconds. For the birds about the same. The skittles one tripped me up, couldn't find it. The other few I found around the same time, the lights at the end I didn't find in time either. It seems I'm quicker when there's not too many colors involved. Still that's spooky.
It's good to hear reports of successful viewing. I've got a 3d / stereogram photo gallery app on the back burner; sounds like a reasonable number of people would be able to view it. There are plenty of guides on how to learn this; some are linked here https://www.reddit.com/r/CrossView/wiki/index/. You-tube used to have support for this; there are still videos tagged yt3d - just regular videos now, not interlaced.
My co-worker printed two paper listings, one with the error, one without, and asked me to count parentheses as he was doing, over a dozen pages. But because I knew this "superpower" trick, I laid out pairs of pages and crossed my eyes. A few seconds later I found and circled the error.
"Ta-daa!" I said. He never forgave me.
I don't recall what these exercises were for, but there were two:
1. Stare at this image of two incomplete cats, and merge them together into a single complete cat: https://www.google.com/search?q=eye+muscle+cat+card
2. This strip of cardboard has a number line on it. Put one end half way down your nose, perpendicular to your face. You will see two lines. Merge them at their furthest point, then merge the next nearest point, repeat. (I think this is called the 'Brock String Exercise', but can't find an image similar to the one I recall.)
There is also one other similar funny ability I have: Vibrating my eyes. I can willingly vibrate my eyes. I don't think it's any useful ability as I just see shaky when I do it but it's fun to do in front of people. It scares some of them. There is actually a community about it in Reddit: https://www.reddit.com/r/Eyeshakers/
”Are these two things the same size?”
”Are these things that are supposed to be evenly spaced actually evenly spaced?”
”Are all these things straight/at the same angle?”
”Is the wallpaper pattern aligned everywhere?”
”Is that surface using a repeating texture?”
Similarly, acoustic ceiling tiles, repeating patterns on wallpaper, rugs, or draperies, building faces, etc.
This may be a superpower to some, or a supertorment to those with OCD ;-)
I never developed stereoscopic depth perception, which I assume is related.
I suspect it's because my left eye is slighty lazy.
But I was able to superimpose the right cat picture onto the left one (it's a lot harder for the more complex sky resort picture). It's pretty eerie, the right picture just slides right up the left one (I did need to figure out the right distance for it).
It doesn't help me pick out the differences though, I mostly only see the right picture, and if try to focus my left eye, the right picture slides out. Still, intersting.
My visual system is pretty weird in general so I don’t know how common an experience this is with others. It’s not bothersome at all because I know what it is but it was a little startling the first few times.
https://developer.nvidia.com/gpugems/gpugems/part-vi-beyond-...
Wait, why isn't there a service for this? Or is there?
On a stereo image sliding the top image is very interesting as areas at different distances fade at different positions.
Here is an example video I made many years ago with the colors inverted as well for visibility: https://youtu.be/k2-ZZz5rwQE?si=UaKcidDRbNZOftbd
You cross your eyes to get the two images to line up, hold it there and then try to adjust the focus of your eyes. It's a neat skill to have.
If it's perfect, the overlapping regions just merge in color, i.e. the cat's paw becomes off-white. If it's not perfect, I still have to attend to which parts are popping in and out. In both cases I still have to compare the merged view to the left and right hand sides.
Although it is very nice for illustrating each eye's contributions to the merged view. Just not an attention-saver.
It's not a great way of showing the image, but it'll do in a pinch.
But in the following few moments, seeing two nearly identical photos side by side soon made me think of stereograms, since I'm into them, and have shot a few in my lifetime.
I then used my eyes to overlap the images.
In binocular overlapped view, the difference loudly draws attention to itself, because it flickers between the two eyes.
It's almost as if there were a blinking LED saying "here it is!"
I can't uncross, now!
I would usually get accused of memorizing all the pictures.
You will get bored or a headache before you stop getting free games using this technique.
You can get stifled by the older machines with faded CRT screens. The newer LCD (that's how old these games are...) are usually better to play on.
then again, i did outperform my entire national cohort at school in almost every subject by a wide margin... an outlier.
the trick however is very clever, but it wont work in more complicated scenarios where attention to detail matters.
EDIT: after doing the first one near the top i tried the rest. with a bit of warm up its very fast. no tricks needed. maybe a relic of playing these games when younger and having a "once in a generation" level of learning power coupled with training it when very young when learning speed is multiplied by a huge scale factor. i had to zoom the last one, but the other two were incredibly fast, close to immediate. sub second.
EDIT2: the warm up was doing the first image once after reading the first few sentences.
EDIT3: this is not a superpower.
Bonus tip: while focused on the overlapping image in the middle, jiggle your screen, and the diff will move around while the rest remains static. This helped me solve the impossible challenge instantly.
I'd love to learn more about the underlying mechanism here. Anyone can point me in the right direction?
{I should have done an actual survey, sorry; felt cute might delete.}
Even the impossible one was harder when trying to use the cross-eyed trick than just visually comparing the two by quickly moving my eyes back and forth.
Of course, the internet being what it is, someone made a version of Bad Apple with it: https://www.youtube.com/watch?v=RLuGJGyCS90
Well I'll be the one to say this blew my mind. somehow creating the third middle image, being able to relax my eyes and even scan around this composite image actually made me giggle out loud on my laptop, a very rare occurrence. Thank you to the author.
This is also how the legendary ”Magic Eye” books were supposed to be viewed. Not by crossing the eyes.
I was able to get a 3rd image to be clearly visible in the middle doing this, on the 2nd image I could definitely seem some spots appear that lead me straight to 3 of them but didn't work for me on the other 2 images.
The pattern-based "magic eye" stereograms are done by looking through the image to focus on a point deeper into the screen further from your eyes.
The latter I think are less painful because they use the more natural depth-perception distances of your eyes instead of using what feels like more unnatural positions, but that might be my bias because I'm a bit farsighted. Maybe they're just more common because they're visually inscrutable at first and so you get the "reveal" of the 3D contour from a single large image instead of two already-visible small ones.
Sent it to my whole family
The way your mind locks in and focuses on the middle one seems a testament to the brain processing behind vision we take for granted
25y ago, i was working behind a 30" tube monitor (a ~35kg hog), with 1 inch thick frontglass.. and one day, one of my eyes started to focus on the (closer)outside of the glass, the other on the (farther)inside of the glass. Could not shake that with closing/blinking. Worse, later, when i got into the car, the closer eye focused on the windshield - instead on the landscape ahead.
Took 1 week of everyday 1-2 hours staring far away at the ocean, to revive. AND removal of the monitor :/
But I never knew this technique could be used to spot the difference between images. Very cool discovery!
Was also able to spot the difference on the coffee beans image: https://i.imgur.com/0TcWvWJ.png
I was able to grab focus for the first image. Found it hard for the second and third image. I focused on the first one and then scrolled down to the second and third - that made it easier for me.
"It's a schooner"
Somehow expect most people to know this, but I guess that's not the case.
Examples include:
1. Delaying the left or right channel by a few ms (Haas effect).
2. De-tuning one of the channels by a few cents
3. Boosting an EQ band on one channel, with a complimentary cut on the opposite channel.
...and many more.
These are usually very subtle changes that our stereoscopic ears have no problem detecting.
In any case, when we need to do some forensic searching for possible differences between two near-identical channels we'll invert the polarity on one channel and then sum them. The resulting delta sticks out like a sore thumb and highlights even then tiniest differences between the files.
So it's fascinating to discover that we can easily do something similar with our eyes to find the differences.
Maybe this: https://en.wikipedia.org/wiki/Blink_comparator
i have ~1 diopter shortsightness. Was less before, slowly going up. So screens are getting blurrier. Have glasses but still try avoid using them.
If i put the (flat edged) TV remote control at about 10cm from my face so it horizontally shadows lower half of both eyes, i see perfectly (without any glasses).
go figure..
it's just that your eyes are gonna be tired after a movie session.
Or at least, makes it a LITTLE bit harder.
2. Now, cross your eyes and aim to overlap both images.
3. Draw the rest of the fucking owl.
Seriously. Ever since my physics teacher in high school tried to get the class interested in stereograms, everyone and every article I see talking about it treat "crossing your eyes" as an atomic, trivial step. It isn't. I for one have no first clue how to do it, it's not a distinct operation I know how to perform. Perhaps this is because I am nearsighted and wear glasses.
Still, I wish articles like these focused on explaining how to do the whole cross-eye thing, because once you master that, everything else becomes instantly self-apparent and doesn't need further explanation (I know because I did manage to accidentally cross my eyes once or twice while looking at a stereogram, so I know how the effect looks like).
EDIT: FWIW, I compensate by using another trick for diffing documents with Mark I Eyeball - get them printed on separate pieces of paper, put one on top of the other, and hold in front of you with some bright light behind you (Sun, or your phone's flashlight, will do). Not as good as crossing your eyes, but something I can reliably do.
And it's also not really a usefull life or even primitive skill, just a byproduct of our double eyeballs, which are meant for redundancy and depth measuring.
Pass.
(Although it was cool to do it once and see the third image in the middle.)
" Someone called out Kevin Smith for this on one of his podcasts. According to Smith, on the day of filming, he asked if the picture really was a sailboat, and the prop master said no. When Smith started questioning this, the prop master said that a) it flashes on the screen too quickly for anyone in the theatre to notice, and b) VHS was too low-resolution for people to freeze-frame it to try it at home. So Smith let it slide.
Smith summed up, "Now, thanks to Blu-Ray, I get people pointing this out to me all the time!" "
https://www.reddit.com/r/MovieDetails/comments/9lf52b/in_the...
So cool!
Typically this utilised a negative photographic plate (so that bright objects appeared as dark against a light background making their presence easier to detect for our visual system), and the plates were rapidly flipped. The object which moved or suddenly appeared and disappeared was the new element.
This works for nearby moving objects (planets, asteroids, comets) which would track against the stellar background, or distant variable ones (supernovae, variable stars, pulsars) which would appear and disappear (or brighten and fade) over time.
Now of course this is automated and direct sensor readings can be interpreted, but the childs' game was at one time Best Scientific Practice.
Described here, "How are asteroids discovered?" <https://catalina.lpl.arizona.edu/faq/how-are-asteroids-disco...>.
There are archives of these astronomical plates, and there are projects which utilise older observations so recorded to make new discoveries even now (or in the recent past). I'd first learned of this visiting the Lick Observatory on Mt. Hamilton near San Jose some years back. Key was that old plates were used to compare current observations using the same 'scope, an otherwise now-archaic instrument but not without its advantages. As I recall, the astronomer doing the study was the same one who'd made the original plates many decades earlier, and was doing this as his own retirement project. There's a description of similar work (including Lick observations) here:
"Astronomy's Photographic Glass Plates: Demonstrating Value Through Use Cases"
<https://journals.library.ualberta.ca/istl/index.php/istl/art...>
On plate archives:
"Preserving an Astronomical Legacy"
<https://skyandtelescope.org/astronomy-news/preserving-an-ast...>
"APPLAUSE: Archives of Photographic PLates for Astronomical USE"
<https://www.plate-archive.org/applause/info/>
(dylan604 noted this use case earlier: <https://news.ycombinator.com/item?id=42657956>)
I’m not sure how this new learned trick, can apply to other stuff… but I’m happy I tried it and it did amazed me haha thanks for the share dude!
Boy was I wrong. This is an actual super power.
/s
0. Pick suitable tool. Firefox works. Notepad++ works. GIMP works. Emacs, not so much, but if you use Emacs, you know that you can fix this
1. Load file A into a tab
2. Load file B into a tab
3. Close all other tabs
4. Hold down the tab switch shortcut key and note the result
For images this is actually pretty decent and I've used it a lot. Good for figuring out what the differences actually are when your image-based tests fail, and similarly after making a speculative change. Let your eyes do the difference operation for you. That's what they're there for.
For text: you'd be better served by some other kind of tool. But text is just an image with letters in it, so the same principle applies. It does work!
(I've previously read a blog post, link to which I of course now can't find, about how old-style Photoshop undo was designed with this sort of thing in mind. Instead of working through the operation queue like normal people, it simply switched repeatedly between previous state and current state - the idea being that you'd make a change that you weren't certain of, then press the key repeatedly to see before and after. No need to think. Thinking isn't appropriate here anyway. Just let your eyes look at what they're seeing.)