How to move one eye on its own (and the science of eye movement)

as a kid I was obsessed with magic hi pictures I just look at them all the time and I became really good at seeing the 3d image quickly in other words through practice I gained extra voluntary control over the movement of my eyes and I retained that ability to this day despite the fact that I don't really look at magic eye pictures much anymore I mean literally one a day Max and it's this extra voluntary control that means I'm good at going cross-eyed and it means that I can move one eye independently of the other which is what I'm going to show you how to do in this video just in a few seconds actually but also as I was researching the video I discovered all these amazing things about the way our eyes move it's really fascinating stuff so I'm going to talk about that as well stick around for it but first of all here is how you move one eye independently over the other the first thing you need to be able to do is go cross-eyed and I think that's something that most people can do probably or at least to some degree but often what people do when they go cross-eyed is that they go like this they look down and there's a good reason for that it makes it easier because you've got this stimulus here you've got something for your eyes to converge on your nose but it's better if you can go cross-eyed whilst looking straight ahead like that and you can practice that you can you can gain that ability if you if you put your finger right in front of your face like that so you're going cross-eyed when you remove your finger your eyes will suddenly converge on something in the distance in my case the camera that I'm filming with what you want to try and do is when you remove your finger just try and slow that conversion so you'll see when you work your finger you'll see a double image and that WH will snap into a single image try and slow that down so the tomb just come together more slowly eventually you'll be able to get those two images to stop so they don't snap together and then with a bit more practice you'll be able to pull them back again and separate them so practice that for a bit so that you can go cross-eyed whilst looking straight ahead the next step for moving one eye on its own is really easy so when you go cross-eyed like that you see double one image drifts to the left the other edge drifts to the right and all you have to do is decide to yourself I am going to follow one of those images I'm not going to have one drift as I've wanted to light I'm just going to track one of them as it moves and it's really not hard it's not like you know entering the heart of stone for roughest fans it's like it's just you just think it and it happens so that's how you do it I'm genuinely interested to know if those instructions are helpful so let me know in the comments if you've been able to move one eye on its own it might take a bit of practice so come back and leave a comment if that's you so let's talk about how eyes move it's really interesting there's the mechanics of it and then there's the neurology of it like what's going on inside your brain so the mechanics first is really cool each eyeball has six muscles attached to it and they kind of splay out as they reach the eyeball so they sort of look like hands I've built a model of how it looks so here we go shut up it's a good model so think about this every time your eyes move is like little hands pulling on your eyeballs inside your skull it's a nice thought isn't it I'm only showing four of the muscles on here these are the muscles that pull the eyeballs this way and this way the other two cause your eyeball to move in this twisting motion it's not something you do very much it's very subtle but it is very important what's really interesting is these modes of eye movement that you have there are four of them four main ones they are saccades they are smooth pursuit vestibulo-ocular and vergence and i want to talk about all of them because they're all interesting actually we've already talked about virgins that's the movement that your eyes make to converge on near and distant objects the one that you can gain voluntary control of to go cross-eyed so saccades a circuit saccades so a cicadas look like the basic eye movement so if you're looking at one thing and you decide that you're going to look something else your I will sack aid from one to the other it's a rapid movement from one place to the next and okay to interesting things about saccades the first is that during a circ aid you are blind so like imagine if you saw what was happening during a circ aid it would just be a blur being a sickening motion blur so instead the communication pathway between your eyes and your brain is shut down like a little bit of information gets through but but not much you assent you're essentially blind during that movement it it's it's like tens of milliseconds but but you don't see anything during that period what's interesting is your brain so your brain is hiding the circuit but it's also hiding the fact that it's hiding it like surely if no information is getting from your eyes to your brain you would see just black during a circadian you kind of have a mini black every time your eyes did that sudden movement but you don't instead your brain just kind of fudge is it fudge is your perception of time and it just tries to fill in the gaps for you so that you don't notice the blackout and you can experience this look in a mirror and look at your left eye then look at your right eye then back to your left keep going back and forth between your eyes and obviously your eyes are moving because you're moving from one to the other but you will never see your eyes move in the mirror because of saccadic masking that that moment of movement masks the actual movement in the mirror if you want to see your eyes move when you dart from one to the other try the experiment again but using the the front-facing camera of your smartphone there's a slight delay between what the camera sees and wants to spray on the screen so your eyes will sir Kade and then you will see it on the screen the second interesting thing about saccades is that they're described as ballistic so the way the eyeball moves it's more like bullet and less like a guided missile what that means is once the eyeball has started to move its trajectory cannot be updated with new information what that means is if I show you a dot on this side of the screen and then I move the dot over to hear your eye wall sir Kade to the new location but if I move the dots again while your eyeball is still moving it will continue to move until it reaches that spot where the dot was it's only once it gets there that your brain can calculate a new saccades to try and catch up to the new location of the dot so if I move dots around on the screen like you know once every 100 milliseconds or so then you won't get to see any of these dots directly they'll all be in the periphery of your vision so that's the Cades but what about smooth pursuit well it's how it sounds really like if you try and track my finger as it moves on the screen your eyes will smoothly pursue my finger in your field of view and what's really interesting about smooth pursuit is that it's completely involuntary like you cannot voluntarily move your eyes smoothly like if I ask you to move your eyes from this finger to this finger you won't be able to do it slowly and smoothly it will always be a sudden seek aid from this finger to this finger or a series of short saccades that gets you from one place to the other the final type of movement is the vestibulo-ocular movement and this is the movement that tries to compensate for the movement of your head and body like if I go like this I'm moving my head around but I'm able to keep my eyes fixated on the lens of the camera and you might think that that's just another example of smooth pursuit like everything in my field of vision is moving around like this and so my eyes are just pursuing smoothly one point in in that moving image but it's not they're separate systems and you can prove it so what you can do is if you close your eyes do this now close your eyes and rest your fingers just lightly on your eyelids and then slowly turn around like this and when you do that you will feel your eyeballs moving underneath your fingers so humans stabilize their field of view against head movement using muscles in their eyes but birds do it differently they using muscles in their necks and that's what this looks like thanks to Peter McIntosh this relationship between voluntary and involuntary motion is really interesting like what's happening inside the brain and it's not just to do with your eyes and any kind of motion that is voluntary or involuntary take breathing for example so breathing is voluntary you can choose to breathe you can choose to not breathe you can hold your breath or you don't have to think about it at all and you'll just breathe and you basically have a junction in the brain so you've got neurons going to the set of muscles that make you breathe and coming into that Junction you've got the involuntary neurons so you know you've got neurons coming from you're kind of ancient lizard brain if you like and you've got neurons coming from the voluntary part of your brain and they can override each other and things like that so generally speaking the voluntary neurons can override the involuntary neurons which is why you can hold your breath but there's some really cool chemistry that goes on around these junctions breathing is a great example basically if there's a drop in oxygen in the brain then the involuntary neurons can override the voluntary neurons at that Junction and you certainly can't hold your breath anymore you're forced to breathe I want to finish this video with a story about a professor of Neurobiology Susan R Barry and she was born with cross eyes so she was stereo blind which means that she doesn't perceive depth in the same way that we do she doesn't have a stereo depth perception like if she goes to see a 3d movie it doesn't work for example her eyes don't converge on objects in the same way that most people do and they received wisdom the wisdom that she was teaching in her classes is that if you don't correct that within the first year then that's it you'll be like that for the rest of your life but then she consulted a developmental behavioral optometrist and she showed her how to take voluntary control of that vergence reflex that we were talking about and she managed to do something that most scientists thought were impossible she gained stereo death perception for the first time and she writes about the experience really eloquently so I'm going to read this out but there's a link to the article in the description and you can jump off and read her other writings from there as well she says my new view of the world was magical enchanting and beyond anything I could have imagined tree branches loomed out toward me or grew up word and closing and capturing palpable volumes of space that I had never seen before this video is made possible by brilliant org if you don't know what that is yet it's a website full of really fun puzzles and problems that help you to think like a scientist and think like a mathematician I'm really grateful that they continued to sponsor this channel because I think it's a really good match like the way they think about education really clicks with what I'm thinking about in terms of you know how people learn so I've stumbled across their eight principles recently they've laid them all out and I wanna talk about one in particular which says that great science and math education should allow for failure and I really believe that I think that if you want to teach someone to love learning you need to teach them to be comfortable with failure it's not fear failure because it's such an important part of the process and it's interesting to see how brilliant have implemented that principle on the website like if you get a question wrong that language is really positive and the interface kind of nudges you towards a discussion of the solution where you can engage with other members of the community to talk about how they reached the right answer it's really good like I feel like the school should be like that you know so anyway check it out for free by clicking on the link in the description today and as a bonus the first 76 people to use that special link will get 20% off annual premium membership should they choose to upgrade I hope you enjoyed this video if you did don't forget to hit subscribe [Music]

Channel: Steve Mould

Views: 1,107,750

Rating: 4.9583182 out of 5

Keywords: explained, understand, voluntary, involuntary, cross eyed

Id: FaC2RXBss2c

Length: 13min 41sec (821 seconds)

Published: Fri Apr 27 2018

Reddit Comments

[u/voicesinmyhand]

Will this make me cross-eyed permanently? I really don't want that to happen.

[u/Varknar]

I can make one eye move outward rather than inward, while keeping one eye looking forward, but I thought maybe I was developing a lazy eye or some type of eye drift. I probably need to get it checked out, I dunno. It's easier to do when I am tired and have been staring at a computer screen all day. Interesting video, thanks for sharing!