“YOU WON’T BELIEVE YOUR EYES!” – Smarter Every Day 142

Hey it’s me Destin. Welcome back to Smarter Every Day. You won’t believe your eyes. You’ve heard this before right? It’s usually like a click bait title to get you to watch an internet video or read a stupid article. But are there cases when you actually can’t believe your eyes? Make this video as large as you can on the screen that you’re watching and we’re gonna do an experiment. Put your head at a set distance from the screen and look at this photo. It’s a lighthouse on top of an island but I’ve inverted the colors. I want you to focus your eyes right on the tip of that lighthouse and don’t move them. I’m gonna be quiet now and I’m gonna let you transport your mind to this island off the coast of Tasmania. [ seagulls ] OK I’m about to invert the picture back but I want you to stay focused on that lighthouse. Are you ready? Here we go. Out of the corner of your eye you should see a pale blue sky and a deep royal blue sea with little light green grass spots on the island. Now, take your eyes and move it to the edge of the island. You see that? There is no color in this picture. It’s a black and white image. Your brain just made up color that wasn’t there. Can you believe your eyes? By the way, just in case you’re curious this is what the original image looked like. OK, so I just showed you a black and white image and for some reason your brain saw something like this. What is happening? Is that something going on with your eye? Or is that your brain? For all we know it might be the optic nerve connecting the two. Let’s investigate a little bit further. A couple of years ago I saw this video on the internet and at first it just looks like a neat little light toy. But my mind saw something way different. I realized for the first time that I literally could not believe my eyes. Not that I didn’t understand what was happening, but I knew that what I was seeing didn’t actually exist. As soon as I saw this video it was very clear to me that the dude that made this was a genius. The bad news is though, he lives hundreds of miles away in the desert. So I’m in a kind of a sleazy hotel and uh, I don’t want to say sleazy. Have you ever seen somebody do something really cool on the internet and you wanted to meet them? Well that’s kinda what happened here. This is Greg. – Hello – And Greg has a pretty interesting gadget that you made? Is that what we’re gonna call it? – That’s what we’re gonna call it. The device. – Did you design this PCB? – I did. – Did you populate it? – I did. That’s a lot of small chips on there, but.. – You’re a geek man. – Yeah I know. [laughs] It gets easier. – How long did it take to populate the board? – It takes about an hour and a half. – You did that whole thing in an hour and a half? – Yeah. – Yeah but can you change a water pump on a 1990 Chevrolet pickup? – [laughs] – So those are LEDs right? – Yeah they’re red green blue RGB LEDs. – That’s pretty cool. Now how are you controlling that? – So these LEDs are mounted on a circuit board that’s mounted on a DC motor. And if I apply power to the DC motor, it spins. And if I time it just right, I can essentially light up any LED anywhere on the circle that I want, as we can see here. – So you just created these bitmaps and then uploaded them through some software that you wrote? – Yep, so this is a 63 by 63 pixel bitmap, and essentially I take that and there’s actually an infrared sensor on the display that can receive data. – Oh look at that. Smarter Every Day. Little homage. So how did you do that? Did you upload that, or.. You did that today didn’t you. – Yes actually I just created that image right before driving out to meet you. – This is pretty amazing. So ok, here’s the deal. I asked you about this because I wanted to do this. I wanted to use this high speed camera to look at what you’ve got here. This is a Phantom Miro that we’re using here. This is a Miro 320S, and we’re gonna setup.. What’s your update rate on the microcontroller? – Um it’s pretty fast. It’s spinning at about 25 revolutions every second. – Ahuh. – And within those it updates 256 times. So we’re looking at about a 200 microsecond rate that the LEDs get updated. – OK so a thousand frames per second is not fast enough, is what you’re telling me. – No. – OK. Alright, well let’s figure out what frame rate we need to hit in order to understand what’s going on here. – Alright. – What do we call these? Are these pixels? Cause it’s not really like a square thing like cartesians, it’s kinda like an arc.. – Right, it’s kind of like an arc pixel. – OK, so what do you call that? – An arxel. – Arxel.. like it. We’re gonna go with that. How far does the LED bar travel for each individual arxel as you call it? – It’s about one and a half degrees. – If it’s only going one to two degrees, then why is my brain still seeing that light the whole time it’s around? Because it’s only one 360th of the sweep, but the rest of it’s dark. According to the high speed camera, which I had to crank up to 5500 frames per second, this is what’s actually happening. Check it out. Those’s dots, or the arxels as Greg likes to call them are kind of flipping around all over the place. Most of the image is dead space. So why is your brain making that image? To understand why the brain sees something that’s not there I found a guy that studies this sort of thing that’s published over 130 different papers on similar topics. OK I’m on a pretty bad Skype connection with Dr Stuart Anstis who is a genius at the University of California San Diego and what do you study Dr Anstis? – [british accent] I study visual perception, in particular visual illusions which tell us about the normal processes of vision, how the eyes send information to the brain. – That’s fantastic. And obviously your accent makes it very clear that you know exactly what you’re talking about because I would expect nothing less from a person who studies visual perception. So I want to understand why my eyeball is seeing something where I know there is not light. Why am I seeing that? – It’s because of persistence of vision, which means the eye averages what it sees over a short period of time. It’s analogous to a camera where you have a long exposure time, and this will give you more light coming in, greater sensitivity, but you have a more sluggish response. So anything moving gets blurred out. – What is the difference in time from the moment the LED is illuminated until my eye registers that the light is there? There has to be a delay time there. What is that? – That delay time varies enormously, over a ten-fold range, anything from 10 to 100 milliseconds. – According to Dr Anstis there’s two things going on, and let’s look at it. Let’s pretend that we have a flashing LED and we want to look at the brain’s response to that LED. First of all he said there’s a delay, so when the LED first comes on, our brain’s not going to immediately see vision, it’s gonna take some finite amount of time later. Secondly he said that the eye averages what it sees over a short period of time. Think about that. If we have a moving average, that means that our vision has some sort of inertia to it. It works like this. As the average comes along and is exposed to that LED flash, it starts to ramp up. As the light goes away, that moving average starts to ramp back down. As the light comes back that average starts to go up again, and instead of having gaps that are complete darkness, we have this nice trough in the bottom. Therefore we have a persistence of vision even though there is no light to see at that point in time. Let’s look back at that slo mo image from before with all the blinking LEDs. Now, let’s add this time average of light and see what the image looks like. Check it out. How cool is that? It looks just like what our eyes see. At what rate would you expect that I would quit seeing a uniform image but I would start to see like a tail dragging across the screen? – Well if the average time is less than one revolution then you’re going to see a gap. But supposing as you say, the propellor goes around in 1/25th of a second, that’s 40 milliseconds. – I get it now. Do you understand? Think about it. Greg’s wheel is rotating at 25 frames per second, and that has to do with the moving time average of the human eye. That’s why this video is at least 25, it’s actually 30 frames per second. If it wasn’t, you would see flickering of the image. So what seems like an imperfection in our eye is actually what smooths things out and makes the world work smoothly for us. That’s pretty awesome. If the people watching this video were students in your class what would you want them to know about Greg’s wheel and the persistence of vision? – [laughs] Well I would say every system has got a limited time resolution The eye has an engineering problem of trading time resolution against sensitivity to light. And in fact it’s got sort of knobs inside which can change that trade-off relationship automatically. The eye is in many ways much cleverer than the camera. It’s a beautiful piece of engineering. – Well thank you very much sir, I really appreciate your time. – Thank you. – Alright I hope you enjoyed this episode of Smarter Every Day. It was sponsored by lynda.com which helps pay for people like Micah who’s a video editor. – Hello. – Who happens to actually have a certification from Lynda. Lynda is like a Smarter Every Day but on very technical topics. So in this particular case, after effects. I had no idea how to do this. So Micah came along and helped me. He actually took a bunch of classes on Lynda and we found one together right? – That’s right. – And what was it called? – Echo. – This was the tutorial that taught me to model persistence of vision using After Effects. But you can learn almost any topic you want. They’ve got Excel tutorials, Photoshop tutorials, even how to edit videos like I do with Premiere. This is not the stuff you’re gonna find on YouTube, this is really high quality tutorials. They’ve got over 100,000 of them. So if you want to support Smarter Every Day, please consider going to lynda.com/smarter You’ll get a 10 day free trial which you can cancel at any time. I wanted to make sure that if you’re supporting Smarter Every Day you’re gonna have a really good experience so that’s lynda.com/smarter You can cancel at any time. I’m Destin, I hope you enjoyed this, feel free to subscribe, if not, no big deal. Hope you’re getting Smarter Every Day Have a good one. OK is there any truth to the rumor that you actually proposed using one of these? – There is some truth. [laughs] As I was finishing up the project I thought to myself, Hey it’d be pretty cool if I could like write messages on here so I decided that’s how I wanted to propose.

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99 Responses

  1. Im Eating Ramen Mom!! says:

    my eyes didnt make color πŸ™

  2. Ultimate goku says:

    What !!πŸ€€πŸ€€πŸ€€πŸ˜•

  3. Kano Mora says:

    It was still black and white when I looked.

  4. robert quinting says:

    No…. My eyes saw a black and white photo

  5. ElZamo92 says:

    Just look at a CRT display. It depends 100% on persistence of vision.

  6. Scandinerdian says:

    So, help me out here: The professor says that the brain can actually adjust to the limitations of light sensitivity vs lag. It seems to be a constant compromise. However if we have a higher exposure (higher intensity of light per surface in the eye), are we then forced to have a higher fps to avoid gaps (since lag or blur, would be less)?

  7. neon says:

    I have never been so scared in my life

  8. Keep Calm and Build Bots says:

    This video was really interesting because although the human eye can detect 1000 frames per second, this aspect of 'visual inertia' causes persistence of vision, causing humans to see things for much longer (relatively) than they are actually there

  9. B3boy says:

    intelligence!!! (thank you)

  10. Isaac Sothern says:

    that illusion literally gave me a headache

  11. thundereye 2233 says:

    Diin't work but saw it worked

  12. snipecor2000 says:

    It didn't work.

  13. Bug Stomper says:

    0:24 My brain must be faulty, because as soon as you switched it to black & white, I saw no colour in it whatsoever.

  14. boyce evans says:

    I love this arxle guy

  15. james dickson says:

    Iv no time for main stream science the are so obviously liers .they are almost laughable .

  16. hhoward14 says:

    I think that might have been the basic principle of how the original mechanical television worked…

  17. steven cowan says:

    Fantastic channel mate .I am getting smarter every day thanks to you πŸ‘Œ

  18. Jack Anthem says:

    error, ; does not compute

  19. Emmanuel David Vazquez Rivera says:

    Super cool

  20. Robert Garscadden says:

    Very interesting.i,m fascinated by thing's like this.

  21. rosssilver says:

    Gayest way to propose ever, did she say yes? lol

  22. Jesse Nealon says:

    Well I thought I saw blue but never saw the green if the grass

  23. jam9able says:

    This the fourth dimension human being haven't yet exploit it…..we need to be spiritual being in able to exploit the fourth dimension human being have been created to exploit God image but we need to be spiritualize to do so.

  24. Neon UwU says:

    when 10 million fire flies.

  25. apatheticAnxiety says:

    Wow what a totally nerdy way to propose!

    …I'd say yes.

  26. Sheikh Maqsood says:

    Thank u….but i request you to use simple English so that we non English people would also understand all this stuff easily

  27. acid junkie says:

    The picture was black and white right from the beginning. I never saw any colours.

  28. Nick Annies says:

    Such a cool video, I love your videos. I'd heard and knew about the persistence of vision a while back…I experimented with balls of chalk on the end of electric motors and used sharp blades to cut shapes into the spinning chalk, which created a form, but when you kill the motor it looked completely different, hence when the motor was spinning it created the illusion of a 'shape' or 'form'. I was 12 years old when I did this, but did not discover the cause of the effect until much later in life, with lasers etc. Great video, thank you!

  29. BEASTUX says:

    Eh nothing new

  30. Miller Dude says:

    My brain didn't do it, I think it's broken

  31. Miller Dude says:

    If you blink while looking it it it wont work, you have to look at it with out blinking to work

  32. Tom A says:

    omg I saw blue water on the bw picture.

  33. M Media says:

    Go thing I don't do drugs…

  34. zztop3000 says:

    Why does this guy remind me of Lynette's husband from "The Desperate Housewives" – series

  35. pr0ject ZEUS says:

    Nothing change

  36. Cliff Yablonski says:

    Heads up display in fighters/attack helicopters have been doing this since the 70's it's hardly new.

  37. BlackWhite HD says:

    I wish Greg would have shown how to make that projector, would have been a lot cooler.

  38. DonutGuy640 says:

    9:31 Anyone else thinking of Cyriak? πŸ˜€

  39. Sean Voss says:

    you make me feel dumb.
    but i'm learning from you every video.

  40. Alpha Omega says:

    doesnt work without viewing the inverted image first which means our brain isn't making up color.

  41. Lazy Koala says:

    MY EYES!!

  42. Lazy Koala says:

    Nah I just saw a flash oh colour

  43. mOcKiNg sPoNgEbOb says:

    1:14 i saw black and white picture and i thought i was supposed to see colors there

  44. Washington Jopir says:

    What is time average of light?

  45. Eugenius Williams says:

    And people still say it was not possible to doctor the 9/11 footage by replacing missiles with planes? Or whatever!

  46. Spunky says:

    I knew from the start that image was black and white because the mountain looked white and if the colors of this image were inverted the original image of a mountain would be black, also water is black and sky is white

  47. Fusion Blade says:

    I was expecting a jumpscare thank you for not doing that

  48. salamanca1954 says:

    "What is happening?" For starters, complementary afterimages. Long known and used.

  49. silver & noise says:

    Visual hysteresis.

  50. salamanca1954 says:

    This is a well conceived and produced video.

  51. Sport Notiz says:

    this is actually insane! things like this safes people so much time, to understand such a simple thing, that a person like me don't have time to research or even ask myself. well done!

  52. Zune Buggy says:

    So I would hypothesize that a firefly's flash is faster than it appears and it makes me wonder how I'm able to zero in and catch one fairly easily. It seems like by the time I see the flash go on and off the firefly would be long gone.

  53. Jake Pearson says:


  54. Ebb says:

    I realized this reality by trying to theorize how does, at some point, a car tire appears to be spinning backwards, when it’s actually moving forward.

  55. Judy Giovannetti says:

    I LOVED THIS! But am on so many sites I get in my inbox everyday, but writing this down! Love ancient history, but this was great too!!

  56. Trisstian p says:

    That Richland bombers shirt tho ! Hmmm I wonder if he’s local


    always wonder what they clever guys are really really up too

  58. anthony bronson says:

    Yes sir its called the peaneal gland…

  59. Juan Mendez says:

    Ha jokes on you I don't see color

  60. Neill LeBlanc says:

    This was awesome! I wonder if all light being admitted from LEDs to incandescent bulbs to TVs are blinking?

  61. Christopher Herald says:

    Awesome content

  62. gt5228z says:

    Destin, Do a video on cathode Ray tube tvs

  63. Willow Klein says:

    Guys if you keep your eyes on the lighthouse then you will still see Color

  64. John Cox says:

    That is a really good explanation.

  65. Proviper666 says:

    ? Lynda = skillshare?

  66. Chigozie Ilozue says:

    I believed it was black and whit so I don’t know about you

  67. Vinod Nair says:

    i saw no colour πŸ™

  68. Jack Robinson says:

    how tdo you program the arcxelsto the right colours tho o.O

  69. jmatt4life says:

    Our brain repopulated color from the inverted colors in the original picture on which we focused.

  70. Tayuss79 says:

    That is mental love your channel

  71. Mr hankie howdeehow says:

    I finally under stand a smarter every day video

  72. laurie Smith says:

    Its all down to light frequency versus the frames per second Frequency versus the rate at which we can Physically process the visual info

  73. FurryFace says:

    my Brain didn't make up any color , the pic was back&white and thats it , so i can still believe my eyes

  74. ブルー says:

    Optics is amazing.

  75. Nate R says:

    Great video!! 😎

  76. Liban Warsame says:

    "The eye is in many ways much clever than camera. It's a beautiful piece of engineering". That is a wise observation.

    Indeed, the human creativity can never match that of the master Creator, Allah, who created the human body in perpect proportion.

    "O mankind, what has deceived you concerning your Lord, the Generous,

    Who created you, proportioned you, and balanced you?

    In whatever form He willed has He assembled you".

    Qur'an 82:6-8

  77. Peggy Churchill says:

    No, my brain saw black and white and I thought "What's this snake oil salesman up to? What's wrong with him? Is he color blind?"

  78. mohdem33 says:

    TIL; I have built in Gsync

  79. Henry Marckisotto says:

    "You did that today didn't you" low key insult

  80. Andrew Bunn says:


  81. ComDam says:

    the picture bit was so cool but after that i started to get bored of the video. the start was cool tho. πŸ™‚

  82. Pat B says:

    Hilarious he is using XC wire to make it.

  83. Buzz Lightyear says:

    This channel has officially been respectfully approved by Star Command

  84. Paul Baker says:

    If you want to know, stop seeing the world as if it is outside of you. Just a hint.

    Correlation does not equal causation

  85. Fada fez says:

    That makes sense…. Actually we are "analog devices", not digital! No 0 and 1, there's a lot in between πŸ™‚

  86. zendogbreath says:

    impressive. the negative image was a color image, right?

  87. The Teen Engineer says:

    thanx that was cool πŸ™‚

  88. Random Railfan Guy says:

    "… If ten million fireflies"

  89. Nikzard Madara says:

    But it doesn't the answer how the brain assumed the colour of the image. It is not something to do with retention of what the eyes have already seen, because the eyes have not seen the colour earlier. Can somebody explain ?

  90. Lewandra Erwin says:

    Thanks. I just had an intellectual argument w some teens on how fast light takes for us to see and how we see light, What, 8 min in the past? I enjoy those types of arguments and what they hold for the future. Love yr honesty in a world of mass deception

  91. Carolina Outdoor Life says:

    OMG The Professor at 5:20 sounds like Marvin the Martian! Hope he does not invent a Plutonium Space Modulator! lol

  92. colehoughton85 says:

    It’s the same thing when you look at a wheel on a car when it’s moving slowly, you see gaps, but when that wheel is moving in a quicker rate such as on a highway you see an almost solid image of the wheel!

  93. Maxon Mendel says:

    The inventor guy must be from Wisconsin

  94. Wak Cackle says:

    Digital to Analog

  95. tyler89557 says:

    I don't believe in eyes.

  96. M Piper says:

    I hope these guys don't accidentally open some portal to another dimension and accidentally let something through that didn't belong in this dimension.πŸ€ͺ


    how bout making a large portable smartphone screen out of this??

  98. Trey Coughlin says:

    I accidentally let my eyes wander right when he switched to black and white, and I was flipping out because I thought it was actually a color image, and that the trick was that I thought it was black and white. I kept darting my eyes around trying to make it go back to normal.
    Guess thats what I get for having the volume so low lol

  99. Trey Coughlin says:

    I can't shake the feeling that this video proves that the book Recursion by Blake Crouch is 100% real and possible.

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