WEBVTT - Why Does Rocking Put Babies to Sleep? 0:00:11.280 --> 0:00:13.080 Hey, everyone, it's Mango here, and I want to tell 0:00:13.080 --> 0:00:15.400 you about another podcast I think you're going to enjoy 0:00:15.600 --> 0:00:19.000 so much. It's called Candy Is Dandy, the world's only 0:00:19.120 --> 0:00:24.520 podcast devote entirely to reviewing candy. Each episode features a 0:00:24.560 --> 0:00:28.000 deep dive into a different candy with history, games, taste tests, 0:00:28.080 --> 0:00:31.360 hilarious guests, and the kind of super nerdy facts we 0:00:31.600 --> 0:00:36.080 at Part Time Genius appreciate so much, like where the 0:00:36.159 --> 0:00:39.600 name Snickers comes from and why butterfingers has a link 0:00:39.640 --> 0:00:43.200 to the atomic bomb. It is smart, it is funny. 0:00:43.240 --> 0:00:45.800 It makes me nostalgic for all kinds of treats I 0:00:45.840 --> 0:00:49.640 remember from my very own childhood. So I really hope 0:00:49.640 --> 0:00:52.360 you'll check it out. Find Candy Is Dandy, the candy 0:00:52.440 --> 0:00:59.560 review podcast wherever you get your podcasts. You're listening to 0:00:59.600 --> 0:01:09.000 Part Time Genius, the production of Kaleidoscope and iHeartRadio. Guess what, Gabe, 0:01:09.440 --> 0:01:09.800 what's that? 0:01:09.920 --> 0:01:10.200 Mango? 0:01:10.720 --> 0:01:13.480 Do you know that babies aren't afraid of heights until 0:01:13.640 --> 0:01:15.280 after they've started crawling? 0:01:15.720 --> 0:01:18.760 Really, so you could go hang gliding with a three 0:01:18.760 --> 0:01:20.240 month old and they wouldn't even bat. 0:01:20.120 --> 0:01:24.400 An eye apparently. I mean, there are lots of reasons 0:01:24.440 --> 0:01:26.320 why you don't want to go hang gliding with a 0:01:26.840 --> 0:01:30.479 three month old, but your baby's fear of heights isn't 0:01:30.520 --> 0:01:33.399 one of them. According to researchers, babies only start to 0:01:33.400 --> 0:01:36.560 fear heights around nine months or so, typically when they 0:01:36.560 --> 0:01:38.640 crawl to the edge of a staircase for the first time, 0:01:38.760 --> 0:01:41.319 or when they're peeking over the side at their changing 0:01:41.319 --> 0:01:44.440 table or something like that. But up until that point, 0:01:44.720 --> 0:01:47.560 a baby might express interest in a ledge or think 0:01:47.600 --> 0:01:51.040 it's amusing, you're curious, but they won't actually be scared of. 0:01:50.960 --> 0:01:54.400 It, which is like very scary when you think about it. 0:01:54.480 --> 0:01:57.600 But I am curious though, Like why would learning to 0:01:57.680 --> 0:02:00.160 crawl be you know, this big game changer for all 0:02:00.200 --> 0:02:03.200 of this, Like why is that what makes babies afraid 0:02:03.200 --> 0:02:03.680 of heights? 0:02:04.080 --> 0:02:06.840 Well, according to new scientists, it's because of how our 0:02:06.840 --> 0:02:09.919 brains change when we first start to move ourselves around 0:02:09.960 --> 0:02:13.200 in different spaces. So when that happens, we suddenly begin 0:02:13.280 --> 0:02:16.240 to process information that we never paid attention to before, 0:02:16.320 --> 0:02:19.360 like what we see in the periphery and how that 0:02:19.440 --> 0:02:23.360 visual information can be used to keep ourselves steady and balanced. 0:02:23.800 --> 0:02:26.960 So when a baby starts moving around, suddenly they're learning 0:02:26.960 --> 0:02:31.000 how to navigate a visual world made of solid, steady surfaces. 0:02:31.160 --> 0:02:33.480 In contrast, the prospect of crawling out into thin air 0:02:33.560 --> 0:02:36.120 doesn't really make any sense, and the result is that 0:02:36.160 --> 0:02:39.119 a drop off now becomes a very scary thing to them. 0:02:39.480 --> 0:02:41.680 But that's just one of the recent developments of baby 0:02:41.680 --> 0:02:43.880 science that I learned about this week. And I know 0:02:43.960 --> 0:02:47.400 we've both got a ton we're excited to share about babies, 0:02:47.440 --> 0:03:11.920 So let's dive in. Hey, their podcast listeners, welcome to 0:03:11.919 --> 0:03:14.800 part time Genius. I am mongishit together, and since Will 0:03:15.080 --> 0:03:17.840 is away this week, I am joined by our good 0:03:18.000 --> 0:03:21.080 pal Gabe Lucier. And on the other side of that 0:03:21.120 --> 0:03:24.160 soundproof glass wearing a shirt that says baby talk will 0:03:24.200 --> 0:03:27.520 get You Nowhere, that's our friend and producer Dylan Pagan. 0:03:27.960 --> 0:03:29.760 And I know he's just wearing the shirt to stay 0:03:29.800 --> 0:03:32.800 on theme with today's show, but it does leave me 0:03:32.880 --> 0:03:34.240 with a few questions. 0:03:34.880 --> 0:03:37.640 Yeah, yeah, you mean, like, why do they make that 0:03:37.680 --> 0:03:38.960 shirt in adult sizes? 0:03:39.560 --> 0:03:42.280 Exactly? That is the first of many questions I have. 0:03:42.720 --> 0:03:45.800 All Right, well, I hate to be like T shirt police, 0:03:45.840 --> 0:03:48.240 but the thing about that shirt, baby talk will get 0:03:48.280 --> 0:03:52.880 you Nowhere, the sentiment is actually false, Like there's good 0:03:52.880 --> 0:03:54.960 reason to think that speaking to your baby in a 0:03:55.000 --> 0:03:58.920 cutees voice isn't as silly as it sounds, and in fact, 0:03:58.960 --> 0:04:01.480 it may even help with length which learning, or at 0:04:01.560 --> 0:04:04.480 least that's the takeaway I got from this twenty seventeen 0:04:04.520 --> 0:04:07.880 study I read this week from the Princeton University Baby Lab, 0:04:08.280 --> 0:04:11.800 which is a real thing. Apparently, the researchers there found 0:04:11.840 --> 0:04:14.680 that women who spoke a wide array of ten different 0:04:14.760 --> 0:04:18.240 languages all used roughly the same timber when speaking to 0:04:18.279 --> 0:04:21.800 infants in a cutesy baby voice. And so the implication 0:04:22.080 --> 0:04:25.479 is that baby talk might be a kind of universal communication, 0:04:25.960 --> 0:04:28.520 one that mothers and fathers both used to connect with 0:04:28.560 --> 0:04:31.560 their babies, and it's also a way to encourage them to, 0:04:31.640 --> 0:04:33.400 you know, try speaking for themselves. 0:04:33.839 --> 0:04:36.440 That is really interesting because I feel like we also 0:04:36.600 --> 0:04:40.479 use the same sing songy speech patterns when we're talking 0:04:40.480 --> 0:04:44.080 to dogs or cats or whatever, and I wonder like, 0:04:44.120 --> 0:04:47.240 are we unconsciously trying to teach them to speak as well. 0:04:47.960 --> 0:04:50.039 Yeah, I mean it could be. I would love that. 0:04:50.200 --> 0:04:53.440 But the other option I read about is that we 0:04:53.520 --> 0:04:56.520 use baby talk anytime we feel like we're speaking to 0:04:56.560 --> 0:05:00.599 someone who doesn't know our language. So babies doll people 0:05:00.600 --> 0:05:03.880 from a different country. If we think someone can't understand us, 0:05:03.960 --> 0:05:06.200 we instinctively turn on the baby talk. 0:05:06.800 --> 0:05:09.480 Oh that's really interesting and it makes you wonder if 0:05:09.480 --> 0:05:12.560 it actually works, Like, do dogs respond better to baby 0:05:12.560 --> 0:05:14.120 talk than to our normal voices? 0:05:14.720 --> 0:05:17.440 Yeah, it's funny because even though we use baby talk 0:05:17.480 --> 0:05:20.640 for animals of all ages, the study I read found 0:05:20.640 --> 0:05:24.080 that puppies were the only ones that responded more strongly 0:05:24.160 --> 0:05:26.680 to the use of baby talk the adult dogs in 0:05:26.760 --> 0:05:29.280 the study. They had like the same level of response 0:05:29.320 --> 0:05:30.920 no matter how their owners talked. 0:05:31.279 --> 0:05:34.080 So, just to recap, Dylan's baby talk will get you 0:05:34.160 --> 0:05:38.560 know where shirt is completely false from the perspective of babies, humans, 0:05:38.680 --> 0:05:42.440 and dogs alike, but accurate when applied to adults of 0:05:42.560 --> 0:05:44.200 either species. Do I have that right? 0:05:44.400 --> 0:05:46.279 Yeah? I think that's the gist of it for anyone 0:05:46.360 --> 0:05:46.840 keeping track. 0:05:46.960 --> 0:05:50.000 Yeah, I am glad we cleared it up. And when 0:05:50.000 --> 0:05:51.800 you think about it, it's kind of a nice reminder 0:05:51.839 --> 0:05:54.080 of just how strange and new everything in the world 0:05:54.160 --> 0:05:57.120 must seem to a baby, because those early years are 0:05:57.200 --> 0:06:00.880 almost nothing but constant learning, figuring out how to move 0:06:00.920 --> 0:06:04.080 their bodies, how to engage with objects and people, how 0:06:04.080 --> 0:06:06.919 to understand and use language, and you know, it seems 0:06:06.960 --> 0:06:09.760 so basic to us as adults, but there's a lot 0:06:09.800 --> 0:06:12.360 of complexity to these processes once you start to break 0:06:12.360 --> 0:06:14.640 them down. And that's really what we're doing today. We 0:06:14.680 --> 0:06:17.960 are exploring how babies perceive the world and how they're 0:06:17.960 --> 0:06:18.600 affected by it. 0:06:18.960 --> 0:06:21.840 Yeah, exactly. And since we started with baby talk, I 0:06:21.880 --> 0:06:23.599 actually want to take a minute to look at the 0:06:23.640 --> 0:06:25.920 other side of that, which is the way that babies 0:06:25.920 --> 0:06:28.640 talk to us. So most people tend to think that 0:06:28.680 --> 0:06:32.520 when babies start talking, they're just imitating adults that they've overheard, 0:06:32.960 --> 0:06:36.600 but it isn't exactly one to one. Like babies talk 0:06:36.640 --> 0:06:39.800 in one word sentences. They leave out word endings and 0:06:39.880 --> 0:06:43.520 function words like pronouns and conjunctions, So they might be 0:06:43.600 --> 0:06:47.200 copying the words they've heard, but they definitely aren't using 0:06:47.240 --> 0:06:49.039 them to talk the way that adults do. 0:06:49.480 --> 0:06:52.000 I love that you're just picking on babies. 0:06:51.720 --> 0:06:53.400 Right now, I'm doing. 0:06:54.560 --> 0:06:56.880 I'm pretty sure they don't have the option to speak 0:06:56.960 --> 0:07:00.760 like adults because you know, word combination, it's gonna be tricky, 0:07:00.880 --> 0:07:04.520 and I'm assuming their brains just aren't ready for that 0:07:04.600 --> 0:07:05.960 kind of complexity. 0:07:05.480 --> 0:07:08.640 Right, Yeah, No, that's right, And you're actually describing something 0:07:08.720 --> 0:07:13.920 that neuroscientists call the mental developmental hypothesis, and that's basically 0:07:14.000 --> 0:07:16.520 the idea that one year old speak in single words 0:07:16.560 --> 0:07:19.800 and short phrases because their brains aren't yet equipped for 0:07:19.840 --> 0:07:23.880 adult speech. But there's another theory, a competing theory called 0:07:23.920 --> 0:07:27.880 the stages of language hypothesis, and that one suggests that 0:07:27.960 --> 0:07:30.720 children might learn to speak in stages, just as they 0:07:30.760 --> 0:07:34.320 do with walking. So in this scenario, speaking in full 0:07:34.400 --> 0:07:36.560 sentences has more to do with how many words a 0:07:36.680 --> 0:07:39.880 child knows rather than you know, how developed their brain is. 0:07:40.600 --> 0:07:44.040 That's pretty interesting, like you build language almost the same 0:07:44.080 --> 0:07:47.160 way you build any other physical skill. But is there 0:07:47.160 --> 0:07:49.600 a way to test which of these theories is correct? 0:07:49.760 --> 0:07:51.680 Yeah, So there was actually a study on this that 0:07:51.800 --> 0:07:54.400 came out of Harvard University way back in two thousand 0:07:54.440 --> 0:07:57.640 and nine, and the researchers looked at the language development 0:07:57.680 --> 0:08:01.160 of a group of international adoptees. So it was twenty 0:08:01.200 --> 0:08:04.320 seven children adopted from China between the ages of two 0:08:04.360 --> 0:08:07.920 and five, and those kids were chosen because you know, 0:08:07.960 --> 0:08:10.520 they would be learning English at an older age than 0:08:10.560 --> 0:08:15.360 most native speakers. So if the mental developmental hypothesis is true, 0:08:15.720 --> 0:08:18.400 then those kids would have had an easier time learning 0:08:18.440 --> 0:08:21.440 to speak fluent English since their brains were, you know, 0:08:21.520 --> 0:08:24.120 already so much more developed than you know, that of 0:08:24.160 --> 0:08:25.640 a native infant. 0:08:25.360 --> 0:08:27.440 And so did they have an easier time. 0:08:28.000 --> 0:08:32.320 Nope. In the end, the adoptees followed the exact same 0:08:32.440 --> 0:08:35.920 track of language development as American born babies, just at 0:08:35.920 --> 0:08:39.360 a faster rate. So despite their extra brain power, they 0:08:39.440 --> 0:08:42.160 still started with one word sentences and then moved on 0:08:42.240 --> 0:08:45.160 to short phrases you know, with missing words and so on. 0:08:45.800 --> 0:08:48.439 And there was also one other important point of overlap 0:08:48.480 --> 0:08:51.800 between the adoptees' experience and that of American born babies, 0:08:52.200 --> 0:08:55.200 and that's that both groups began combining words into longer 0:08:55.240 --> 0:08:59.280 sentences when their vocabularies reached the same sizes. And that 0:08:59.360 --> 0:09:02.520 suggests that it's really how many words you know that matters, 0:09:02.559 --> 0:09:05.160 not how old you are or how developed your brain is. 0:09:06.280 --> 0:09:10.800 That's fascinating. So, speaking of baby vocabulary, did you know 0:09:11.000 --> 0:09:13.800 that the type of words a baby learns to speak 0:09:14.000 --> 0:09:19.080 first largely depend on which language that they're learning. For instance, 0:09:20.000 --> 0:09:22.680 this is really crazy to me. English speaking babies tend 0:09:22.679 --> 0:09:26.560 to learn a bunch of nouns first. While Mandarin speaking 0:09:26.600 --> 0:09:28.800 babies typically start with verbs. 0:09:29.120 --> 0:09:31.720 Oh that is cool. So is that just like it 0:09:31.760 --> 0:09:34.080 comes down to how the different languages are structured. 0:09:34.600 --> 0:09:38.040 Mm hmm, exactly. So Mandarin is a much more verb 0:09:38.120 --> 0:09:41.560 focused language than English. Is, like you can frequently leave 0:09:41.600 --> 0:09:44.080 out the subject of a sentence entirely and just let 0:09:44.120 --> 0:09:46.880 the verb do all the work. And of course that's 0:09:46.880 --> 0:09:49.920 seldom the case in English. But I was reading about 0:09:49.920 --> 0:09:53.760 this in Scientific American and the author Meredith Knight had 0:09:53.800 --> 0:09:57.960 this nice breakdown of these different approaches to language. She writes, quote, 0:09:58.040 --> 0:10:01.600 English speaking parents tend to use big, one size fits 0:10:01.640 --> 0:10:06.800 all verbs as they emphasize nouns cars, trucks, buses, bicycles, 0:10:06.800 --> 0:10:11.720 and scooters. They all simply go. Mandarin speakers do the opposite. 0:10:11.840 --> 0:10:15.520 They use catch all nouns such as vehicle, but describe 0:10:15.559 --> 0:10:20.240 action driving, riding, sitting on, pushing with very specific words, 0:10:20.280 --> 0:10:22.760 which you know is something that just never would have 0:10:22.760 --> 0:10:23.280 occurred to me. 0:10:23.760 --> 0:10:26.400 Yeah, no, me either. It actually makes me wonder you 0:10:26.440 --> 0:10:29.480 know how deep those differences go, Like is it just 0:10:29.520 --> 0:10:31.760 a linguistic thing, or does the way you talk about 0:10:31.760 --> 0:10:34.200 the world affect, you know, the way you see it too? 0:10:34.559 --> 0:10:36.360 I could see making the case for the example I 0:10:36.480 --> 0:10:39.880 just gave, like American culture puts such an emphasis on 0:10:39.920 --> 0:10:42.640 the individual, and that could be a reflection of our 0:10:42.720 --> 0:10:46.160 languages focus on nouns and subjects or vice versa. And 0:10:46.240 --> 0:10:48.520 while I'm obviously not an expert on Asian culture, it 0:10:48.600 --> 0:10:51.839 does seem to be more community minded, like the action 0:10:52.120 --> 0:10:55.080 or outcome is what counts rather than the person behind it. 0:10:55.320 --> 0:10:57.960 And that kind of outlook seems pretty in line with 0:10:58.040 --> 0:11:00.000 how verb centric Mandarin is. 0:11:00.200 --> 0:11:02.480 Okay, yeah, I could see that. And so there's clearly 0:11:02.520 --> 0:11:05.480 some kind of connection between how we speak and how 0:11:05.480 --> 0:11:07.760 we see the world. But one thing I learned this 0:11:07.800 --> 0:11:10.120 week that I never would have suspected is that there's 0:11:10.200 --> 0:11:13.560 also a connection between how we hear and how we 0:11:13.640 --> 0:11:15.960 move our tongues. Have you heard this? 0:11:16.960 --> 0:11:19.760 I mean, I know snakes can smell with their tongues, 0:11:19.800 --> 0:11:22.880 but I've never heard about anything, you know, doing with babies, 0:11:23.000 --> 0:11:26.000 and many hearing with their fair enough. 0:11:26.040 --> 0:11:27.920 So the idea is that, you know, the way we 0:11:27.960 --> 0:11:30.720 perceive speech is directly tied to the areas of the 0:11:30.760 --> 0:11:34.320 brain that control mouth movements. And if that's the case, 0:11:34.400 --> 0:11:37.400 then we don't understand speech simply because we hear it, 0:11:37.720 --> 0:11:41.280 but because we recognize the mouth movements that produce the sounds, 0:11:41.360 --> 0:11:44.160 we know. This was all confirmed by a study back 0:11:44.200 --> 0:11:47.520 in twenty sixteen. It was headed by a cognitive scientist 0:11:47.600 --> 0:11:51.920 named Alison Bruder at the University of British Columbia, and 0:11:52.080 --> 0:11:54.720 what she did was she gathered a group of twenty 0:11:54.760 --> 0:11:57.840 four six month old babies from different cultures, none of 0:11:57.840 --> 0:12:00.280 whom had started talking yet, and then she put the 0:12:00.320 --> 0:12:03.480 babies in front of a screen displaying a checkerboard pattern 0:12:03.800 --> 0:12:07.760 and played them two recordings, an English D sound repeated 0:12:07.800 --> 0:12:11.400 several times and a Hindi D sound played only once 0:12:11.440 --> 0:12:14.080 at a time. And if you haven't heard the Hindi 0:12:14.120 --> 0:12:17.800 D sound before, I'm guessing you have. The main thing 0:12:17.840 --> 0:12:19.959 to know is that it's made by moving the tongue 0:12:20.000 --> 0:12:22.040 farther back on the palette than you would for the 0:12:22.120 --> 0:12:24.880 English D sound. And so the idea was that if 0:12:24.920 --> 0:12:27.480 the babies could tell the difference between the two sounds, 0:12:27.559 --> 0:12:30.000 then they would pay closer attention to the screen whenever 0:12:30.040 --> 0:12:33.319 the sounds alternated from one to the other. And when 0:12:33.400 --> 0:12:36.360 you know, that's exactly what happened. I tracking revealed that 0:12:36.480 --> 0:12:40.040 regardless of cultural background, the babies all stared at the 0:12:40.040 --> 0:12:42.440 screen longer when the sound switched. 0:12:42.960 --> 0:12:46.080 First of all, I do know the Hindi alphabet, and 0:12:46.240 --> 0:12:51.360 it's amazing because it's organized in a way where it 0:12:51.440 --> 0:12:53.200 moves from the front of your mouth to the back 0:12:53.240 --> 0:12:56.320 of your mouth for each letter, and so like you 0:12:56.360 --> 0:13:00.640 can as the words get harder, you can hear how 0:13:00.720 --> 0:13:03.319 like a D in Hindi is is much much stronger 0:13:03.360 --> 0:13:07.560 than American DA, I guess. But all of this is 0:13:08.000 --> 0:13:10.360 really fascinating to me. Like the idea that the babies 0:13:10.400 --> 0:13:14.360 can track these screens or they're the scientists are using 0:13:14.400 --> 0:13:17.320 eye tracking to figure out what they're paying attention to, 0:13:17.520 --> 0:13:21.640 is really fascinating. Yeah, but what does any of that 0:13:21.679 --> 0:13:23.560 have to do with, like tongue movement as you were 0:13:23.559 --> 0:13:24.680 talking about before. 0:13:24.800 --> 0:13:27.400 Right, Yeah, so nothing yet. But you know, after that 0:13:27.559 --> 0:13:31.520 initial round of testing, Bruder tried something different. So she 0:13:31.600 --> 0:13:34.440 gave each of the babies a teething toy that blocked 0:13:34.480 --> 0:13:36.680 the movement of their tongue, and then she played the 0:13:36.720 --> 0:13:40.360 recordings again and this time with you know, with the 0:13:40.400 --> 0:13:43.439 teethers in place, the babies didn't seem to notice the 0:13:43.480 --> 0:13:46.480 difference in sounds at all. Again, this is like, according 0:13:46.559 --> 0:13:50.160 to the eye tracking, so so Bruder tried one last test. 0:13:50.559 --> 0:13:53.600 She replaced the tongue blocking teethers with ones that did 0:13:53.679 --> 0:13:57.360 not impede the tongue's movement, and you know, when you 0:13:57.400 --> 0:14:00.200 know it, the babies once again showed signs that they 0:14:00.240 --> 0:14:02.319 understood the difference in d sounds. 0:14:02.800 --> 0:14:04.920 So not only were they using their tongues to mark 0:14:04.960 --> 0:14:08.440 the difference between the sounds, they were doing this before 0:14:08.480 --> 0:14:10.480 they even knew how to speak themselves. 0:14:10.679 --> 0:14:13.320 Right, It's wild, isn't it. And and the thing is, like, 0:14:13.400 --> 0:14:16.320 this isn't something we stop doing once we grow up. 0:14:16.480 --> 0:14:18.760 Like there was one study out of Texas a few 0:14:18.840 --> 0:14:22.360 years back where researchers had adult Native English speakers try 0:14:22.400 --> 0:14:24.560 to pronounce a made up sound, you know, one that 0:14:24.640 --> 0:14:28.400 doesn't belong to any language. And so first the participants 0:14:28.440 --> 0:14:31.160 were played the sound and asked to copy it. Then 0:14:31.240 --> 0:14:33.360 they were asked to do this again, but on that 0:14:33.480 --> 0:14:36.360 second time, they were shown real time images of the 0:14:36.400 --> 0:14:39.600 position of their tongue as they tried to pronounce the sound, 0:14:40.080 --> 0:14:43.240 And amazingly, the participants were much more likely to make 0:14:43.280 --> 0:14:46.160 the sound correctly once they had been given that you know, 0:14:46.320 --> 0:14:47.320 visual feedback. 0:14:47.760 --> 0:14:51.080 So did those participants not have pacifiers as kids. Is 0:14:51.120 --> 0:14:54.120 that why they could learn like that? There would need to. 0:14:54.120 --> 0:14:56.160 Be a lot more research before we can say there's 0:14:56.200 --> 0:14:58.640 like a real link between using a teether and a 0:14:58.680 --> 0:15:02.600 delay in language learning. And you know, according to Bruderer quote, 0:15:02.760 --> 0:15:05.680 at this point, I don't think that these data suggests 0:15:05.800 --> 0:15:09.320 parents should be taking away teethers or soothers. The majority 0:15:09.320 --> 0:15:12.320 of infants are chewing on something semi regularly most of 0:15:12.360 --> 0:15:14.840 the day, and most of these infants do go on 0:15:14.920 --> 0:15:16.360 to develop speech normally. 0:15:17.440 --> 0:15:21.160 Oh good, because I remember what a relief it was 0:15:21.760 --> 0:15:24.160 to pop a pass fire in my kid's mouths, Like 0:15:24.360 --> 0:15:29.040 we were instantly happier in those moments. But now that 0:15:29.080 --> 0:15:31.600 we've covered how babies learn language, let's take a step 0:15:31.640 --> 0:15:34.240 back and talk a little bit about brain development. But 0:15:34.520 --> 0:15:39.120 before we do, we've got to take a quick break. 0:15:52.000 --> 0:15:53.880 You're listening to part Time Genius and we're talking about 0:15:53.880 --> 0:15:56.800 the latest signs on babies, all right, Gabe. So I 0:15:56.840 --> 0:16:00.160 mentioned up front how babies are learning pretty much NonStop 0:16:00.200 --> 0:16:02.640 for the first few years of their lives, and I 0:16:02.680 --> 0:16:05.720 actually have a factor to back that up. According to research, 0:16:06.000 --> 0:16:08.680 during the first three years of a child's life, their 0:16:08.720 --> 0:16:12.200 brains grow at a faster rate than any other body part. 0:16:12.640 --> 0:16:16.400 In fact, roughly sixty percent of a baby's metabolic energy 0:16:16.560 --> 0:16:20.600 sixty percent is dedicated just to brain growth, compared to 0:16:20.720 --> 0:16:24.320 a paltry twenty five percent that the adult brain uses. 0:16:24.400 --> 0:16:28.040 So and in the first ninety days alone, a baby's 0:16:28.040 --> 0:16:30.960 brain will more than double its volume, growing to write, 0:16:31.000 --> 0:16:34.760 around fifty five percent of its final size. Isn't that insane? 0:16:35.280 --> 0:16:38.080 Yeah, that's amazing, But it also seems a little weird, 0:16:38.120 --> 0:16:40.520 doesn't it, Like why are we all born with such 0:16:40.640 --> 0:16:42.920 underdeveloped brains? Why it grows so much? 0:16:43.360 --> 0:16:46.040 One idea is that humans are social animals by nature, 0:16:46.160 --> 0:16:48.480 so it makes more sense for our brains to wire 0:16:48.520 --> 0:16:51.440 themselves in the presence of the people who will ultimately 0:16:51.520 --> 0:16:54.720 raise us. Right, But if you ask me, it's mostly 0:16:54.720 --> 0:16:57.760 out of consideration for our mothers, because it takes a 0:16:57.800 --> 0:17:00.320 big head to hold a fully developed brain, and the 0:17:00.440 --> 0:17:04.280 human birth canal has its limits. 0:17:04.480 --> 0:17:06.159 That's a good point. I hadn't thought of that, but 0:17:06.840 --> 0:17:09.840 you're absolutely right. And besides, that whole setup does seem 0:17:09.920 --> 0:17:12.480 to be working well enough for us. Like you know, 0:17:12.520 --> 0:17:15.040 I was reading this study where researchers found that seven 0:17:15.119 --> 0:17:18.159 month old babies already show activity in the areas of 0:17:18.160 --> 0:17:21.919 the brain associated with the physical aspects of speech, like 0:17:21.960 --> 0:17:25.280 the tongue movements I mentioned earlier. So a baby's brain 0:17:25.400 --> 0:17:28.560 is already laying the groundwork for speech long before they 0:17:28.560 --> 0:17:29.720 say their first word. 0:17:30.000 --> 0:17:32.320 Which is amazing. And that's not the only thing that 0:17:32.359 --> 0:17:35.400 babies can do before they've even learned to talk. According 0:17:35.440 --> 0:17:39.320 to a study published in twenty eighteen, pre verbal babies 0:17:39.359 --> 0:17:43.480 can also think logically and even make rational deductions with 0:17:43.680 --> 0:17:47.760 wills astounding to me. The researchers took a group of 0:17:47.800 --> 0:17:52.240 babies between twelve and nineteen months and they had them 0:17:52.320 --> 0:17:55.439 repeatedly inspect a pair of objects. So there was a 0:17:55.440 --> 0:17:59.200 toy dinosaur and a flower. And next the objects were 0:17:59.200 --> 0:18:01.720 placed behind black wall and the babies were shown in 0:18:01.880 --> 0:18:05.760 animation of a cup scooping up the dinosaur. After that, 0:18:05.800 --> 0:18:07.880 the wall was taken away, and what do you think 0:18:07.960 --> 0:18:08.240 was there? 0:18:09.359 --> 0:18:11.679 The flower? Hopefully I can get this right. 0:18:11.880 --> 0:18:15.560 Very good. All right, that's what you'd expect. But here's 0:18:15.600 --> 0:18:18.800 the thing. The flower was only there half of the time. 0:18:19.040 --> 0:18:21.399 In the other cases, the wall would be removed and 0:18:21.440 --> 0:18:25.920 a second dinosaur toy would be sitting there. And even 0:18:25.920 --> 0:18:28.320 though the babies couldn't explain what was wrong and words, 0:18:28.320 --> 0:18:31.680 they could definitely tell something was off about that second dinosaur. 0:18:31.800 --> 0:18:34.680 So once again, the researchers were able to use eye 0:18:34.680 --> 0:18:37.320 tracking to show that the infants stared a good deal 0:18:37.400 --> 0:18:41.120 longer when the unexpected object appeared behind the wall, as 0:18:41.160 --> 0:18:44.040 if they were confused by it. And not only that, 0:18:44.200 --> 0:18:48.560 their pupils also dilated when they saw these strange outcomes. 0:18:48.560 --> 0:18:51.360 And that's actually something that happens to adults when we're 0:18:51.359 --> 0:18:54.240 working through logic problems, which is something I'd never heard before. 0:18:54.280 --> 0:18:55.479 And yeah, it's really amazing. 0:18:55.520 --> 0:18:58.879 That's really neat. I'm kind of impressed babies, But also like, 0:18:58.920 --> 0:19:01.879 imagine how much fun those researchers had just confusing the 0:19:01.880 --> 0:19:03.200 heck out of a bunch of babies. 0:19:03.280 --> 0:19:05.840 Like, I know, the idea of like doing all this 0:19:05.960 --> 0:19:08.280 mischief and a baby lap seems really fun in. 0:19:08.240 --> 0:19:11.520 The great it's a great job. Yeah. And you know, 0:19:11.600 --> 0:19:14.520 another factor that's really important though in development is of 0:19:14.520 --> 0:19:18.520 course sleep, because just like adults, a baby's brain consolidates 0:19:18.560 --> 0:19:22.040 memories and you know, cements them into knowledge while they're sleeping. 0:19:22.560 --> 0:19:25.320 And according to a twenty seventeen study out of Germany 0:19:25.640 --> 0:19:29.040 that process starts super early on, at around six to 0:19:29.119 --> 0:19:31.880 eight months, when babies, you know, first begin to learn 0:19:31.920 --> 0:19:35.680 that words have meaning and aren't just random noises. And 0:19:35.920 --> 0:19:38.520 what's even more incredible is that the length of the 0:19:38.720 --> 0:19:42.480 nap may determine how strongly a memory is formed. 0:19:42.880 --> 0:19:45.840 That's crazy, And so how do you even measure something 0:19:45.880 --> 0:19:47.880 like that, like the strength of a memory? 0:19:48.200 --> 0:19:50.639 Yeah right, it's pretty abstract, But you know, if you're 0:19:50.680 --> 0:19:53.359 a German researcher, you do it by making up a 0:19:53.359 --> 0:19:56.640 bunch of nonsense words like Zeuser's and baffles. 0:19:56.840 --> 0:20:00.119 That's what they did, which sounds very doctor seuss that 0:20:01.280 --> 0:20:02.280 please explain more. 0:20:02.480 --> 0:20:06.119 Yeah, all right, let me start over. So the researchers 0:20:06.119 --> 0:20:08.520 wanted to test the effect of a mid day nap 0:20:08.760 --> 0:20:10.720 and you know, see what effect it had on a 0:20:10.720 --> 0:20:14.000 baby's recall. So to do this fairly, they had to 0:20:14.000 --> 0:20:16.359 be sure to test them with words they couldn't have 0:20:16.440 --> 0:20:19.160 already known. So that's why they came up with Zeussers 0:20:19.280 --> 0:20:21.959 and Boffels. Those were the made up names that they 0:20:22.000 --> 0:20:24.960 assigned to a pair of toy like objects that the 0:20:25.000 --> 0:20:28.639 kids had never seen before that day. So at first 0:20:28.680 --> 0:20:31.239 the kids couldn't tell which objects should be called by 0:20:31.359 --> 0:20:34.760 which name, But then after a thirty minute nap, they 0:20:34.760 --> 0:20:38.600 could easily distinguish a zeuser from a baffle. And after 0:20:38.640 --> 0:20:42.159 a fifty minute nap, something even more amazing happened. The 0:20:42.240 --> 0:20:45.600 researchers spotted a brain pattern in their young test subjects 0:20:45.800 --> 0:20:49.200 that had only ever been seen in older children and adults. 0:20:49.600 --> 0:20:52.720 It's called the N four hundred component, and it's a 0:20:52.760 --> 0:20:55.840 clear sign that the infants had created a solid mental 0:20:55.960 --> 0:20:59.560 link between the words and the objects they represented. Isn't 0:20:59.600 --> 0:21:01.840 that impress That is incredible. 0:21:02.600 --> 0:21:05.359 So, while we are on the subject of sleep, I 0:21:05.400 --> 0:21:09.040 came across a pair of recent studies that finally offered 0:21:09.040 --> 0:21:11.560 an answer to the angel question of why rocking a 0:21:11.640 --> 0:21:13.080 baby helps them fall asleep. 0:21:13.600 --> 0:21:15.720 See, I didn't even know that was something people were 0:21:15.760 --> 0:21:18.879 like asking. I just think your parents were so happy 0:21:18.920 --> 0:21:22.520 that rocking work that nobody stopped to question it. And why. 0:21:22.640 --> 0:21:26.320