WEBVTT - You Are Here: Proprioception 0:00:03.080 --> 0:00:05.960 Welcome to Stuff to Blow Your Mind from how Stuff 0:00:05.960 --> 0:00:13.440 Works dot com. Hey, you wasn't a stuff to blow 0:00:13.480 --> 0:00:17.040 your mind. My name is Robert Lamb and I'm Julie Douglas. Julie, 0:00:17.079 --> 0:00:19.160 what are you doing? You're closing your eyes and you're 0:00:19.239 --> 0:00:22.160 you're touching your nose. I'm touching my nose. I am 0:00:22.200 --> 0:00:25.640 being a pro pre exception champ right now, oh, pro 0:00:25.800 --> 0:00:30.080 pre exception. Yeah. The subject of today's episode, and this 0:00:30.120 --> 0:00:33.080 really gets down to what may seem at first like 0:00:33.120 --> 0:00:38.400 a very basic concept, right, where is our body? Where 0:00:38.440 --> 0:00:41.760 are we? Where are we in terms of time and space? 0:00:41.920 --> 0:00:44.879 Where our arms? Just sort of basic stuff that we 0:00:44.960 --> 0:00:48.360 take for granted on a near constant basis. Yeah, this 0:00:48.520 --> 0:00:51.080 at first glance seems kind of like a stoner question. 0:00:51.400 --> 0:00:54.400 Where is my body? It's right here? Um, but you're 0:00:54.480 --> 0:00:56.120 right if you look at a little bit closer. It's 0:00:56.160 --> 0:01:00.160 amazing that we can locate ourselves in our body. That 0:01:00.240 --> 0:01:03.440 we have this meta sense that combines our brains knowledge 0:01:03.520 --> 0:01:06.399 of what our muscles are doing with a feel for 0:01:06.440 --> 0:01:08.759 the size and the shape of your body. Because as 0:01:08.760 --> 0:01:11.480 we know, um, the way that we take in data 0:01:11.600 --> 0:01:15.360 and we parse it in our brains is not always. Um, 0:01:15.520 --> 0:01:19.760 so straightforward, it's not always actually correct. So of course 0:01:19.760 --> 0:01:21.840 we're going to talk about some weird things happening with 0:01:21.840 --> 0:01:25.040 appropriate exception. Just to go back to the what you 0:01:25.080 --> 0:01:26.840 were doing earlier with your nose though, I'm going to 0:01:26.920 --> 0:01:29.560 try it myself, and I encourage listeners who are not 0:01:29.600 --> 0:01:32.480 trying Okay, let's see or otherwise engaged to do this 0:01:32.520 --> 0:01:34.680 as well. Closing my eyes and then my hand is 0:01:34.720 --> 0:01:36.160 out to the side, and then I'm going to reach 0:01:36.200 --> 0:01:39.759 in with my finger and I'm going to attempt to 0:01:39.760 --> 0:01:43.600 touch the bridge of my nose. And I got it here. 0:01:43.959 --> 0:01:46.520 Oh I can't there's a headphone over it. But but 0:01:46.600 --> 0:01:48.680 I would have had the headphone not I was kidding. 0:01:48.720 --> 0:01:52.800 You actually did get the bridge of your nose. Yeah, okay, good, good, good. 0:01:53.240 --> 0:01:55.360 So what was that of that all about? How did 0:01:55.360 --> 0:01:58.120 I find my nose? Right? Because I couldn't see where 0:01:58.160 --> 0:02:02.040 my nose was. I couldn't here where my You could 0:02:02.160 --> 0:02:05.320 use echolocation like a bat to determine where my my 0:02:05.400 --> 0:02:08.560 hand was and then guided in towards my nose. Um, 0:02:08.600 --> 0:02:11.680 I couldn't smell where my finger was and then negotiate 0:02:11.760 --> 0:02:13.760 it into place. Yeah, I was about to say this 0:02:13.840 --> 0:02:16.160 is not one of those here's one of your five senses. 0:02:16.240 --> 0:02:18.880 Because we've talked about that, there were pretty limiting to 0:02:18.960 --> 0:02:21.520 say we have five senses. There's obviously stuff going on 0:02:21.560 --> 0:02:24.160 beyond that. And if you've ever hovered your hand over 0:02:24.280 --> 0:02:27.200 a hot iron, you know that automatically, right. You didn't 0:02:27.240 --> 0:02:30.560 get that sense of heat from licking that hot iron, 0:02:30.919 --> 0:02:34.560 from smelling it, from tasting it, from touching it, um 0:02:34.560 --> 0:02:37.160 from seeing it. There was another thing going on with 0:02:37.240 --> 0:02:39.400 the nerves and your fingers that were saying, hey, here's 0:02:39.440 --> 0:02:43.280 some data about that object. So that's what this meta 0:02:43.280 --> 0:02:45.440 sense appropriate reception is. But you can't get into the 0:02:45.480 --> 0:02:48.360 meat of it until you kind of talk more about 0:02:48.480 --> 0:02:52.440 the nuts and bolts of what's happening inside of your 0:02:52.480 --> 0:02:55.280 body and how that connects your mind and body. Yes, 0:02:55.280 --> 0:03:00.280 we're talking about American philosopher and psychologist William James two 0:03:00.280 --> 0:03:04.440 through nineteen ten. Very important thinker, a lot of ideas 0:03:04.440 --> 0:03:07.160 that were especially in this case controversial at the time 0:03:07.760 --> 0:03:11.079 and really ahead of of of his time in terms 0:03:11.120 --> 0:03:14.240 of the way he was thinking about our experience of 0:03:14.280 --> 0:03:17.120 reality and how our our brain engages and all of that, 0:03:17.400 --> 0:03:22.000 and he came up with a thought experiment involving a bear. Yes, 0:03:22.080 --> 0:03:24.280 now this was covered in a Radio Lab episode, but 0:03:24.320 --> 0:03:25.840 we wanted to bring it up because it is so 0:03:26.160 --> 0:03:30.360 central to our conversation today. This thought experiment was imagine 0:03:30.400 --> 0:03:33.080 you're walking through the woods and a bear attacks, Okay, 0:03:33.360 --> 0:03:35.520 or just shows up. Really, that's that's enough for me. 0:03:35.840 --> 0:03:39.280 That shows up. And he's wondering that feeling, that emotion, 0:03:39.440 --> 0:03:43.080 that fear, what is that feeling made up of? Where 0:03:43.160 --> 0:03:47.040 is it really coming from? And so what he gets 0:03:47.120 --> 0:03:50.960 into is this idea that it's your body kicking off 0:03:51.040 --> 0:03:53.200 the sense of fear. In other words, it's not your 0:03:53.240 --> 0:03:56.920 emotions that you feel at first, it's your body having 0:03:56.920 --> 0:04:00.280 the response. It reacts to the stimuli first, and then 0:04:00.280 --> 0:04:03.440 the chain reaction informs your body of how to feel 0:04:03.760 --> 0:04:07.240 emotionally or your brain how to feel. So this was 0:04:07.280 --> 0:04:10.040 tested out by the idea that people who are paralyzed 0:04:10.080 --> 0:04:13.600 from the neck down wouldn't exhibit fear. This is what 0:04:13.720 --> 0:04:17.360 he thought, right, because he's again arguing that your body 0:04:17.960 --> 0:04:21.719 is essentially feeling what's happening and feeling the fear and 0:04:21.720 --> 0:04:24.400 then informing your brain on how to think. And so 0:04:24.520 --> 0:04:27.080 if therefore, if the if the body were cut off 0:04:27.080 --> 0:04:30.840 from sensation, then it wouldn't the brain would not have 0:04:30.880 --> 0:04:32.880 a body to tell it to be afraid of the bear, 0:04:34.000 --> 0:04:36.320 right exactly. And so he thought thought, okay, well, if 0:04:36.320 --> 0:04:38.720 you're paralyzed in the neck down, then this should bear 0:04:38.760 --> 0:04:42.280 out right. But he finds out that this is not 0:04:42.520 --> 0:04:44.880 just as cut and dried as he had hoped. This 0:04:45.040 --> 0:04:47.560 is not, in fact happened. People who are paralyzed the 0:04:47.560 --> 0:04:50.599 neck down still experience fear and and could still be 0:04:50.640 --> 0:04:54.520 eaten by a bear from just a very physical, literal sense. Yes, 0:04:55.200 --> 0:05:00.839 not exactly. Yeah, However, some such three years so later, 0:05:01.400 --> 0:05:04.839 neurologist Antonio Dimazzio, the director of the Brain and Creativity 0:05:04.839 --> 0:05:09.000 Institute at the University of Southern California, who is a 0:05:09.000 --> 0:05:12.680 paraplegic psychologist, I thought there might be something to this 0:05:13.080 --> 0:05:18.280 because he said that his emotions weren't as strong since 0:05:18.600 --> 0:05:22.880 um becoming paralyzed. And so he conducted studies of able 0:05:22.880 --> 0:05:25.720 bodied people who became paralyzed and found that they reported 0:05:25.720 --> 0:05:30.400 this same sense of lessening and feelings feeling less sad 0:05:30.560 --> 0:05:33.479 or less happy. As we bring this up because once 0:05:33.480 --> 0:05:37.640 again we see, as Dimazio says, our being is rooted 0:05:37.800 --> 0:05:41.120 in a body state. Yeah, it comes back again and 0:05:41.160 --> 0:05:44.080 again our podcast to that that idea we rolled out 0:05:44.120 --> 0:05:47.080 of the man on a horse versus the centaur. Right, 0:05:47.440 --> 0:05:49.600 there's the the old notion that our brain is this 0:05:49.880 --> 0:05:53.440 rider on a horse and the body just obeys the mind, 0:05:53.480 --> 0:05:55.200 and that's all there is to it. But the more 0:05:55.240 --> 0:05:57.440 we understand about how our brain works and how our 0:05:57.480 --> 0:05:59.800 body works, we see that it's more of a center 0:06:00.000 --> 0:06:03.120 model where the rider and horse are one. You can't 0:06:03.400 --> 0:06:06.360 you can't take the brain apart from the body without 0:06:06.400 --> 0:06:08.840 losing a part of the overall self. Yeah. I was 0:06:08.880 --> 0:06:11.400 thinking about this morning when I was driving in I thought, 0:06:11.440 --> 0:06:13.039 when was the last time I felt like I was 0:06:13.120 --> 0:06:16.680 just punched in the gut from information I was taking in? 0:06:17.360 --> 0:06:19.839 And actually wasn't that long though, And uh, I thought, 0:06:19.880 --> 0:06:22.799 you know what that was exactly it? I felt that 0:06:23.440 --> 0:06:28.520 physical in my stomach and then I had a cascade 0:06:28.600 --> 0:06:32.520 of emotions that followed it. Yeah. I think they brought 0:06:32.600 --> 0:06:36.160 this up in the Radio Lab episode. Well, they were 0:06:36.160 --> 0:06:39.160 talking about our own memories of feeling fear. But it 0:06:39.200 --> 0:06:41.840 made me think about reading stories in which someone encounters 0:06:41.839 --> 0:06:45.040 something fearful, which which I frequently find that because I 0:06:45.080 --> 0:06:48.080 read a lot of horror and suspense. But but when 0:06:48.080 --> 0:06:50.520 you when you read these stories, it's never something like 0:06:50.880 --> 0:06:54.799 and then Randolph encountered a ghost and had the idea 0:06:54.839 --> 0:06:56.760 in his head that he should feel afraid. No, it's 0:06:56.800 --> 0:07:01.480 always the author always describes a visceral reaction to something horrifying. 0:07:01.839 --> 0:07:06.480 You know, hearts are leaping, skin is crawling, um bowels 0:07:06.560 --> 0:07:11.480 or maybe avoiding. But but but that stuff comes immediately before, 0:07:11.600 --> 0:07:16.840 sometimes separated by seconds, minutes, days, hours, whatever, before they 0:07:16.880 --> 0:07:21.000 actually are able to assemble what's happening in their mind. Yeah, 0:07:21.040 --> 0:07:24.160 that's why that that cliche of being punched in the 0:07:24.160 --> 0:07:27.040 gut is so true, because we have an innate sense 0:07:27.040 --> 0:07:31.440 of this pre pre reception working on our emotions. Right. Um, 0:07:31.520 --> 0:07:35.920 so again, let's talk about approprioception. What is it? It 0:07:36.040 --> 0:07:41.160 is actually stimuli relating to position, posture, equilibrium, or our 0:07:41.280 --> 0:07:46.120 internal conditions. Um. It is the sense or rather senses 0:07:46.200 --> 0:07:49.320 of position and movement of our limbs and trunk, the 0:07:49.440 --> 0:07:52.400 sense of effort and the sense of force and the 0:07:52.480 --> 0:07:55.880 sense of heaviness, and all of this information coming together 0:07:55.920 --> 0:08:00.320 in the brain to form a picture of who we are, well, 0:08:00.360 --> 0:08:02.640 not well, not as much who we are in this scenario, 0:08:03.080 --> 0:08:05.400 but what we are, what are parts are composed of, 0:08:05.400 --> 0:08:08.120 what those parts are doing, and where we physically are. 0:08:08.360 --> 0:08:11.160 And it's interesting because if you, if you just take 0:08:11.160 --> 0:08:13.720 any given moment, we tend to fall back on a 0:08:13.840 --> 0:08:17.520 visual understanding. If you, if you ask yourself the question, well, 0:08:17.560 --> 0:08:20.040 what's my body doing and where am I? We think, oh, well, 0:08:20.200 --> 0:08:22.920 this is me because I see me and I see 0:08:22.960 --> 0:08:25.040 my surroundings, so I know where I am. We tend 0:08:25.120 --> 0:08:27.920 to think just visually about it. But it's far more 0:08:27.960 --> 0:08:31.200 complicated than that. Yeah, and that comes down to body schema, 0:08:31.440 --> 0:08:35.040 in this sense of body ownership. So you in body schema, 0:08:35.120 --> 0:08:37.360 you have this model of where your mind thinks your 0:08:37.400 --> 0:08:40.160 body is in time and space. And in the paper 0:08:40.480 --> 0:08:45.600 and an implicit body representation underlying human position sense, authors 0:08:45.760 --> 0:08:49.360 long Goo and Haggard say that human position sense must 0:08:49.360 --> 0:08:54.480 refer to a stored body model, and this model has 0:08:54.520 --> 0:08:58.319 the body's metric properties like body parts, size and shape. 0:08:58.720 --> 0:09:01.640 And in their study they found that without cues from 0:09:01.640 --> 0:09:04.120 a person's environment or their own muscle movements, and we'll 0:09:04.120 --> 0:09:07.760 talk more about that, that a person's implicit mental map 0:09:07.760 --> 0:09:10.280 to say, their hand when they tried to recreate it 0:09:10.360 --> 0:09:14.160 for the researchers was greatly distorted, and it bears out 0:09:14.200 --> 0:09:17.080 this idea that you can't have just the mental map 0:09:17.160 --> 0:09:20.520 alone of the body schema to to really know where 0:09:20.520 --> 0:09:22.840 you are in time and space, you have to have 0:09:22.920 --> 0:09:26.920 other clues. Yeah, it made me instantly think of Game 0:09:26.960 --> 0:09:29.760 of Thrones for some reason. Um, have you watched any 0:09:29.800 --> 0:09:32.120 of the show? Well, you know there are a lot 0:09:32.160 --> 0:09:36.760 of scenes, inevitably, especially when things get a little more warlike, 0:09:37.520 --> 0:09:40.240 where you'll have general staring down at a map and 0:09:40.240 --> 0:09:43.280 then they'll be pieces on the map representing where the 0:09:43.400 --> 0:09:46.520 army is. Now, for a general to command an army, 0:09:46.520 --> 0:09:49.880 you're having to depend on that general sending out messages 0:09:50.160 --> 0:09:52.160 to the to the army to command where they're going 0:09:52.200 --> 0:09:55.080 to go. And then those individual units in the in 0:09:55.120 --> 0:09:57.360 the army, you're sending back messages to the general to 0:09:57.480 --> 0:10:00.920 let uh he or she know where the army is. 0:10:01.040 --> 0:10:03.280 And then all of that is put on a map, 0:10:03.360 --> 0:10:06.240 and then the general has a has an idea in 0:10:06.280 --> 0:10:09.800 his or her head regarding the shape of the army, 0:10:09.840 --> 0:10:12.840 the formation of the army, where the army is and 0:10:12.880 --> 0:10:17.160 where it is going, and not to encourage a horse 0:10:17.200 --> 0:10:20.319 and rider view of the mind body connection. But that's 0:10:20.400 --> 0:10:23.600 kind of what's happening here. There's all this data coming 0:10:23.600 --> 0:10:26.760 together and it's an assembling too, and it's really kind 0:10:26.760 --> 0:10:30.920 of a complicated, um, cognitive process. I mean, the human 0:10:30.920 --> 0:10:33.760 experience is more like a tapestry the more we look 0:10:33.800 --> 0:10:35.719 at it. But but that's kind of what's going on 0:10:36.080 --> 0:10:38.280 in this in this body schemma. Well, yeah, because if 0:10:38.280 --> 0:10:41.000 you're looking at this map that these men on the field, right, 0:10:41.120 --> 0:10:44.359 you could kind of look at the vestibular and kinesthetic 0:10:44.440 --> 0:10:47.319 systems as being some of those men. However, they are 0:10:47.400 --> 0:10:51.520 not appropri reception, right um, you know alone. They have 0:10:51.640 --> 0:10:54.839 to be working in tandem to create that picture. So 0:10:54.920 --> 0:10:57.480 when we talk about the vestibular system, we're talking about 0:10:57.480 --> 0:11:00.640 the master controller of our balance and spatial orientation. And 0:11:00.679 --> 0:11:04.000 when we talk about kinesthetic system, we're talking more about 0:11:04.040 --> 0:11:08.679 motion and behavior, or rather even the habits of movements, 0:11:08.760 --> 0:11:11.720 like your eyes between the computer screen and your keyboard. 0:11:12.480 --> 0:11:15.120 So that's some of the data that comes in. But 0:11:15.200 --> 0:11:18.080 according to Joseph Bennington Castro and he's writing for Ion 0:11:18.200 --> 0:11:21.640 nine quote comparatively pro pri reception has more to do 0:11:21.720 --> 0:11:24.880 with body position and focuses on the cognitive awareness of 0:11:24.920 --> 0:11:27.080 the body of space, so it's not just those two 0:11:27.120 --> 0:11:32.760 elements of the stibular and kinesthetic. And this kind of 0:11:32.800 --> 0:11:35.920 gets us into this weird area too, because people will 0:11:35.960 --> 0:11:40.360 sometimes say, well, sure, pro preeception is kind of a medicine, 0:11:40.480 --> 0:11:45.400 but it couldn't be like alongside one of the five senses, right, 0:11:45.520 --> 0:11:48.439 because when we talk about the five senses, we're talking 0:11:48.480 --> 0:11:53.320 about experiencing the outside world, whereas pro preeception allows us 0:11:53.360 --> 0:11:56.439 to understand the physical place within that world. So that's 0:11:56.520 --> 0:11:57.719 I just want to bring that there's a bit of 0:11:57.800 --> 0:12:01.120 quibbling when we talk about this as it's well, one 0:12:01.160 --> 0:12:03.600 thing about it, though, I feel like with with site, 0:12:03.760 --> 0:12:08.160 with smell, with hearing, these are all process processes that 0:12:08.160 --> 0:12:10.839 that seem a lot simpler based on that sort of 0:12:10.840 --> 0:12:14.520 take it for granted every day um experience. But as 0:12:14.600 --> 0:12:16.720 as we've explored on the show, when you start looking 0:12:16.760 --> 0:12:19.120 at site in the way site works, or how smell works, 0:12:19.200 --> 0:12:22.760 or or how hearing works, all these are are far 0:12:22.800 --> 0:12:25.480 more complicated than we give them credit on a daily basis. 0:12:25.480 --> 0:12:27.120 I mean, just on hearing alone, you get into the 0:12:27.120 --> 0:12:29.839 two different ways that you hear the world hearing with 0:12:29.880 --> 0:12:33.000 the with your inner ear hearing with your skull. You 0:12:33.040 --> 0:12:35.280 can you can take just about any of these these 0:12:35.280 --> 0:12:38.240 senses and you can divide them up into into more 0:12:38.240 --> 0:12:41.760 complicated systems, especially touch, as we mentioned earlier, you can 0:12:41.760 --> 0:12:45.160 get into all the various ways that are our sense 0:12:45.200 --> 0:12:47.719 of touch interacts with the world. I agree. I think 0:12:47.760 --> 0:12:50.520 that pro preception is just right there alongside with the 0:12:50.559 --> 0:12:53.320 other senses in the way that you can view it 0:12:53.400 --> 0:12:56.679 as pointill is um right um. Each one of those 0:12:56.760 --> 0:13:01.800 dots creates that picture of whatever that sense is. So 0:13:02.120 --> 0:13:04.160 it gets us to this idea of how does our 0:13:04.200 --> 0:13:07.120 brain keep track of our body? Anyway? Yes, how does 0:13:07.160 --> 0:13:09.360 it do that thing that it does? We're gonna take 0:13:09.360 --> 0:13:11.760 a quick breaking when we come back. We're gonna jump 0:13:12.040 --> 0:13:21.840 into that question. All right, we're back, and we're gonna 0:13:21.840 --> 0:13:24.480 talk about how our brain keeps track of our body. 0:13:24.600 --> 0:13:27.319 So we're gonna go sort of into the nitty gritty 0:13:27.320 --> 0:13:29.480 in a second. But let's get this obvious part out 0:13:29.480 --> 0:13:31.880 of the way when we talk about equilibrium and orientation, 0:13:31.920 --> 0:13:36.400 because in humans, gravity, position, orientation, those are all registered 0:13:36.400 --> 0:13:40.880 by tiny greens called odo life moving within two fluid 0:13:40.960 --> 0:13:43.120 filled sacks in the inner ear in response to any 0:13:43.200 --> 0:13:47.240 change or position and orientation and their motion is detected 0:13:47.280 --> 0:13:50.679 by sense hairs. So rotation is detected by the inertial 0:13:50.960 --> 0:13:55.120 lag of fluid and the semi circular canals acting on 0:13:55.200 --> 0:13:58.200 the sense hairs. Okay, let's getting the weeds with all 0:13:58.240 --> 0:14:01.960 that stuff. So you have central nervous system integrating signals 0:14:01.960 --> 0:14:05.640 from the canal to perceive rotation in three dimensions. In 0:14:05.760 --> 0:14:10.440 the meantime, if you're saying getting off an elevator, let's 0:14:10.480 --> 0:14:13.520 slow mo this and figure out how your brain is 0:14:13.559 --> 0:14:16.360 then figuring out how it's transitioning from one place to 0:14:16.360 --> 0:14:19.440 another and where it is, right, because we've mentioned before 0:14:19.440 --> 0:14:21.720 the elevator's magic. The door opens and we're in a 0:14:21.720 --> 0:14:24.480 different setting, and I suddenly have to figure out where 0:14:24.520 --> 0:14:26.440 I am, which way is right, which way is left, 0:14:26.600 --> 0:14:29.480 which way leads to the castle, which way leads to 0:14:29.520 --> 0:14:32.320 certain death, at least that's how it is in our building, right. 0:14:32.840 --> 0:14:34.440 So that's when you get into this idea that pro 0:14:34.560 --> 0:14:38.600 prereception uses receptors located in the skin, muscles and joints. 0:14:38.760 --> 0:14:41.680 And if we slow mo this, we can see when 0:14:41.680 --> 0:14:45.880 we've got a microscope here, Uh, we're inside actually the muscle, now, 0:14:46.760 --> 0:14:51.640 muscle spindles, signaling the angle of related joints and telling 0:14:51.640 --> 0:14:53.600 the brain, hey, this is going on. And then you 0:14:53.640 --> 0:14:56.600 get stretch receptors getting in on the game. Yeah, and 0:14:56.600 --> 0:15:00.200 these are detecting small movements of the limbs. So again 0:15:00.240 --> 0:15:02.640 it's just general ideas of what are the limbs doing, 0:15:02.760 --> 0:15:05.120 what kind of what kind of movements are taking place, 0:15:05.160 --> 0:15:07.480 what kind of force is taking place? Yeah, just another 0:15:07.600 --> 0:15:11.400 dot in the point as um picture. And then within 0:15:11.480 --> 0:15:15.360 the tendons that attached to muscles two bones, there are 0:15:15.520 --> 0:15:21.000 PreO pre aceptors called Goldie tendon organs, which would be 0:15:21.040 --> 0:15:24.400 clocking the muscle tension and reporting about that. Yeah. This 0:15:24.440 --> 0:15:27.440 gets into how much force am I exerting? Right, So, 0:15:27.560 --> 0:15:29.720 which is something that can get a little out of 0:15:29.760 --> 0:15:33.440 whack if you are, say, really worn out or maybe inebriated, 0:15:33.720 --> 0:15:36.560 but you need to know how much if you're putting 0:15:36.600 --> 0:15:39.600 into your efforts. Yeah, you get that sense of effort 0:15:39.640 --> 0:15:42.200 because all of those different processes are informing like, okay, 0:15:42.240 --> 0:15:44.280 this is how much force I'm exerting, as you say, 0:15:44.600 --> 0:15:49.080 and then that's getting reported to the cerebellum, which would 0:15:49.120 --> 0:15:52.920 then take that information and try to determine the location 0:15:53.000 --> 0:15:56.280 and the movement of body. Parts, and finally it would 0:15:56.360 --> 0:15:59.320 match that up to the body schema or that stored 0:15:59.400 --> 0:16:03.040 body mob well that we talked about. But and here's 0:16:03.040 --> 0:16:09.120 the rub body schema. Appropri Receptive cues aren't always reliable, Yeah, 0:16:09.120 --> 0:16:13.360 because especially body schema. We've we've discussed before how the 0:16:13.400 --> 0:16:16.800 fact that body schema is notable is key to our 0:16:17.680 --> 0:16:21.560 success as they cool using organism because if you remember 0:16:21.560 --> 0:16:24.200 from our our episode on tool using tool use, when 0:16:24.240 --> 0:16:27.480 we use a tool, be it an ink pin, a hammer, 0:16:27.600 --> 0:16:31.000 or a battle axe, the brain adapts to that tool 0:16:31.080 --> 0:16:34.160 and incorporates it into the body schema, which works to 0:16:34.200 --> 0:16:37.600 our advantage this particular life hack, if you will, when 0:16:37.640 --> 0:16:40.240 we need to write something hamm or something, or chop 0:16:40.320 --> 0:16:43.640 someone's head off. So you can see how when someone 0:16:43.680 --> 0:16:47.360 looks at a rubber hand, for instance, they might think 0:16:47.480 --> 0:16:50.680 that it's their own. Not initially, of course, but as 0:16:50.680 --> 0:16:53.960 you say. This idea that something becomes part of you 0:16:54.760 --> 0:16:59.600 um is steeped in a study by Marcello Constantini who 0:17:00.120 --> 0:17:04.680 had subjects view stimulation of a rubber hand and at 0:17:04.680 --> 0:17:07.040 the same time their own hand was touched in the 0:17:07.119 --> 0:17:11.560 same manner. Okay, so there succeeded at the table. Have 0:17:11.640 --> 0:17:13.760 your own hand. Here there's another rubber hand next to it. 0:17:15.240 --> 0:17:17.600 That hand is being stroked. Your hand is being stroked. 0:17:17.640 --> 0:17:20.360 So you have the visual information of these two arms 0:17:20.720 --> 0:17:25.080 being stroked, and then you have the sense data reaching 0:17:25.080 --> 0:17:28.160 your brain as well of a hand being stroked. Yeah, 0:17:28.240 --> 0:17:30.359 I mean they come to feel like that rubber hand 0:17:30.480 --> 0:17:32.440 is part of their own body. And this is called 0:17:32.480 --> 0:17:36.600 appropri receptive drift, and it's an example of how easy 0:17:36.640 --> 0:17:41.720 it is to have a spatial mismatching and um in 0:17:41.800 --> 0:17:45.639 the abstract of the paper that Constantini has says, current 0:17:45.720 --> 0:17:49.920 sensory evidence about what is me is interpreted with respect 0:17:49.960 --> 0:17:55.160 to a prior mental body representation, meaning that this idea 0:17:55.280 --> 0:17:57.760 of where we are who we are is kind of 0:17:57.960 --> 0:18:01.240 easily messed with. In act, you can take the same 0:18:01.280 --> 0:18:03.960 idea and you can you can extrapolate it a little 0:18:04.000 --> 0:18:07.760 more and actually make the test subject feel as if 0:18:07.760 --> 0:18:10.399 they have three arms. And for this we look to 0:18:10.480 --> 0:18:15.640 a two thousand eleven study from Sweden's Carolinska Institute UH 0:18:15.760 --> 0:18:18.720 and this this is pretty pretty amazing against similar in 0:18:18.760 --> 0:18:21.160 a sense to the rubber hand illusion. They created an 0:18:21.160 --> 0:18:24.640 experiment where subjects had a prosthetic but realistic rubber arm 0:18:24.840 --> 0:18:27.680 placed right next to their right arm. And then the 0:18:27.760 --> 0:18:32.199 experimenters started touching both right arms with a brush in 0:18:32.240 --> 0:18:36.840 the same location, trying to make identical brushstrokes in time 0:18:37.000 --> 0:18:40.080 and location, so similar again to what we saw we 0:18:40.080 --> 0:18:43.040 saw in the rubber arm. And I remember this is 0:18:43.080 --> 0:18:45.560 a first person view of this. They're they're seeing this 0:18:45.680 --> 0:18:48.720 as their arms. Imagine across the room, right, I manage 0:18:48.760 --> 0:18:51.320 yourself at that table, looking down at your one left arm, 0:18:51.600 --> 0:18:53.760 your right arm, and then this plastic right arm there 0:18:53.760 --> 0:18:57.400 as well, and some stranger is stroking it um And 0:18:57.480 --> 0:19:00.680 what happens is is pretty crazy. According to head researcher 0:19:00.880 --> 0:19:05.040 Arvid Gurtustan, what happens is a conflict arises in the 0:19:05.080 --> 0:19:07.520 brain concerning which of the right hands belongs to the 0:19:07.560 --> 0:19:12.520 participant's body, which one could expect. What one could expect 0:19:12.640 --> 0:19:15.080 is that only one of the hands is experienced as 0:19:15.160 --> 0:19:18.399 one's own, presumably the real arm. But what we found, 0:19:18.400 --> 0:19:22.240 surprisingly is that the brain solved this conflict by accepting 0:19:22.359 --> 0:19:25.399 both right hands as part of the body image and 0:19:25.440 --> 0:19:28.760 the subject experience having an extra third arm. So again 0:19:28.760 --> 0:19:31.200 it gets into that same idea of the body scheme 0:19:31.240 --> 0:19:33.560 is saying, all right, my the end of my left 0:19:33.560 --> 0:19:35.520 hand is a battle axe. Now, okay, we can roll 0:19:35.600 --> 0:19:38.120 with it. And here the body schema is updating and saying, 0:19:38.119 --> 0:19:42.320 all right, is a third arm. It's psychologically before to like, 0:19:42.359 --> 0:19:45.080 how do people accept some some piece of information that 0:19:45.280 --> 0:19:48.280 is starkly different from what they thought was happening. Well, 0:19:48.280 --> 0:19:51.040 they just accept it, right, Um, So it's kind of 0:19:51.119 --> 0:19:54.720 not to you know, surprising that this would happen. But 0:19:55.240 --> 0:19:59.800 how do the researchers know for sure that the participant 0:19:59.840 --> 0:20:03.440 is really accepting this body part as their own. Well, 0:20:03.480 --> 0:20:06.480 you've got to you've got inflict little pain, you gotta 0:20:06.560 --> 0:20:11.720 at least bring out a knife. And that's what they did. Uh, 0:20:11.760 --> 0:20:15.480 They threatened the arm with a knife, and they saw 0:20:15.520 --> 0:20:18.800 the participants a lynch and then you know, maybe it 0:20:18.840 --> 0:20:20.600 was just because they saw a knife. So how else 0:20:20.640 --> 0:20:25.000 would they measure that response? Well with a goalvonic skin response, 0:20:25.080 --> 0:20:28.119 which would measure the amount of sweat um, which of 0:20:28.160 --> 0:20:30.400 course is one of those things that's a telltale sign 0:20:30.400 --> 0:20:33.480 of fear. Now you watch the video. I didn't. Now 0:20:33.520 --> 0:20:37.160 I'm imagining the researchers are there gathered around this individual 0:20:37.240 --> 0:20:39.480 with the third plastic arm there, and they've done some 0:20:39.560 --> 0:20:42.200 gentle stroking of the real arm and the plastic arm 0:20:42.240 --> 0:20:46.080 to to inspire this sense of of of having three limbs. 0:20:46.200 --> 0:20:48.560 And then imagine one of the researchers reaching under the table, 0:20:48.560 --> 0:20:52.080 pulling out a dagger and just stabbing, just nailing that 0:20:52.240 --> 0:20:54.840 that third plastic arm to the table so that the dagger, 0:20:54.880 --> 0:20:57.960 you know, vibrates and quivers, and then the test of 0:20:58.000 --> 0:21:01.440 you just shrieks and uh and away. Is that what happened? 0:21:01.720 --> 0:21:05.439 Exactly what happened? No? No, but yeah, kind of except 0:21:05.480 --> 0:21:07.320 for like they didn't like, you just did this big 0:21:07.440 --> 0:21:10.120 arm movement that was big, overarching. I mean they brought 0:21:10.160 --> 0:21:12.520 out the knife and then they brought it up to 0:21:13.160 --> 0:21:17.960 the hand. Um, so it wasn't any sudden movement. But 0:21:18.160 --> 0:21:20.479 you know, obviously there was an implied threat there. Well, 0:21:20.480 --> 0:21:23.040 they're probably standards in practice for the sort of experiment. 0:21:23.080 --> 0:21:25.200 There's a certain way you have to threaten your test 0:21:25.240 --> 0:21:28.640 subjects with a knife. Well, and they explored that. They 0:21:28.640 --> 0:21:34.000 explored this idea more by having someone have a mannequin 0:21:34.080 --> 0:21:37.520 right across from them and then having these little goggles 0:21:37.600 --> 0:21:42.280 on that gave them the vision of being the mannequin. 0:21:42.600 --> 0:21:45.639 Does that make sense? Yes, they're they're wearing basically virtual 0:21:45.680 --> 0:21:48.480 reality goggles. They put them in the point of view 0:21:48.600 --> 0:21:51.080 of the mannequin. Yes, they see the mannequin, and you can. 0:21:51.400 --> 0:21:53.919 The video is great because it shows how they're this 0:21:54.040 --> 0:21:56.840 view of looking down at their mannequin body, and so 0:21:56.920 --> 0:21:59.440 the same sorts of things happened. They have a paint 0:21:59.440 --> 0:22:02.960 brush that's stroking them gently, and then of course all 0:22:03.000 --> 0:22:05.960 of their responses are being measured. Uh, and then the 0:22:06.040 --> 0:22:09.600 knife comes out and it goes right straight across the stomach. 0:22:10.440 --> 0:22:13.560 And so again, what you're doing here is you're removing 0:22:13.760 --> 0:22:18.240 that distance. Um, you're changing it from a third person narrative, 0:22:18.320 --> 0:22:22.000