Language Development

In this video I provide an overview of language development in children. Children learn thousands of words within a matter of a few years and they seem to effortlessly pick up and apply the rules of grammar, first in their telegraphic speech and later in more complex sentences. Errors of overgeneralization reveal that by age 4 or 5 children already have an understanding of grammatical rules and are able to apply these rules to new words, which can also be demonsrated in the Wug Test. There is a critical period for language development and children who are deprived of language and do not have sufficient exposure before age 7 may be unable to ever fully develop linguistic fluency.

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The Wug Test demonstration with Steven Pinker:

Video Transcript:

Hi, I’m Michael Corayer and this is Psych Exam Review. In the previous video I mentioned that children seem to naturally acquire the language that they’re exposed to so in this video I want to go into a little more detail on this process of language development.

One thing that happens is children acquire vocabulary and they acquire vocabulary very, very rapidly. Within their first few years children are able to learn thousands of words. Now this brings up some questions about the conditioning approach, right? If we try to explain this using behaviorism, we see that it’s far too rapid for each individual word to be reinforced or punished, right?

It just simply couldn’t be the case that that mom and dad sit down and reinforce every single correct word that the child uses. This would be too slow. Instead it seems that we are prepared to learn words very quickly without reinforcement and one way that this occurs is what’s called fast mapping. Fast mapping refer to the idea that young children are able to connect the sounds of a particular word with the meaning of that word after just a single exposure.

So we have this arbitrary pattern of sounds that make up the word and that gets connected to the meaning of the word and this can happen just from hearing the word once. So, you know, the child sees something and asks “what’s that?” and mom says “that’s a doggie” and now the child knows the word dog. And a week later the child sees a doggie, points to it and says “doggie”. It’s like they’ve connected those sounds with the meaning immediately after this single exposure. So this is part of the explanation of how we’re able to acquire so many words so quickly.

When children first start speaking they speak in just single words but eventually they start stringing words together and they start with two-word sentences. This is called telegraphic speech. The reason that it’s called telegraphic speech is that it’s like a telegram in that it’s only the most important words for communicating meaning. Children leave out all of the extra words, the function words, so even though they’re constantly hearing words like “the”, “of”, “and” they somehow have learned that these words don’t really matter. These sounds are just like grammatical fluff that allow us a little bit more precision but that when you want to communicate meaning you don’t necessarily need those, right?

So if you want a cookie you don’t need to say “I want a cookie” you can just say “want cookie” and the meaning is clear.

So the idea is that this telegraphic speech focuses on the content words, the words that have meaning, and the children tend to ignore function words, words that serve grammatical purposes. This actually indicates that by ignoring those words they actually understand that those words are just serving grammatical purposes. They know that those words aren’t the ones that have meaning. The ones that have meaning are the nouns and the verbs and so those are the ones you should worry about speaking first and, you know, I’ll get to figuring out where to put “of” in the sentence later on.

Another thing that happens with this telegraphic speech is that it starts following the syntactical rules of the language that the child is learning. So for instance when the child says “big doggie” like they see a large dog and say “big doggie” they’re already showing that they kind of understand how grammar works in English and that you tend to put an adjective before a noun. Nobody’s given them explicit instruction in this, the child’s two or three years old at this point and so nobody’s sitting down and saying “make sure that you always put your adjectives before your nouns”. I mean the child doesn’t even know what an adjective is but they’re able to apply these rules and it shows that they’re naturally coming to understand the grammatical rules of the language.

Children start doing this around age two or three but around age four or five something interesting starts happening. They actually start making errors in their grammatical rules. This brings us to what’s called over-generalization or you may also see this called over-regularization.

This refers to the idea that the children start applying grammatical rules where they’re not supposed to be applied. So the child will say something like “she hitted him” or “he runned to the store” or, you know, “I bringed my bag”. What’s happening here? Well, again conditioning doesn’t really seem to work to explain this because the child is not hearing and being reinforced for these things. It’s not the case that mom and dad are saying “hitted” and “runned” so rhe child is not just mimicking or modeling the behavior that they’re hearing.

They’re coming up with this on their own and this means that even though they’re misapplying the rule, it shows that actually they know the rule. They’ve sort of picked up on this idea that if you want to make something into the past tense, if you want to say that something already happened, well if you have this nice little -ed rule and that is it you just put -ed onto the end of the word and now it means that it already happened in the past tense in some way.

Now again, the child hasn’t had explicit grammatical instruction on this. Nobody sat down and said “here’s how you make the past tense” right? But just by being exposed to the language the child starts realizing “hey this seems to be how this works” and “oh great, now I can make the past tense and I can do it every time” and they just start doing it with every single word that they want to put into the past tense rather than realizing that there are exceptions to this. That you say “ran” rather than “runned”.

Ok, so another way that we can see this over- generalization which actually demonstrates that even though they’re making a mistake, it shows that they actually know the grammatical rule. We see this in what’s called the Wug Test. This was created by Jean Berko Gleason and the Wug test is that you introduce something that the child has not seen before and you introduce a word that the child has not heard before. So this eliminates the possibility that the prior conditioning or prior exposure is influencing what the child is going to say.

So you know, let’s, I don’t know, we’ll make some creature here, I don’t know what this is. This is a Wug. Ok, this is one wug. Ok, so I take this here and I show it to the child and I say this is a wug and then I show them a card with two of these and I say here are two ___ and I let the child complete the sentence.

What does the child say? “Here are two wugs.” Ok, so what does this tell us? Well, this tells us that the child understands the grammatical rule. It understands that putting an S onto a word makes it plural. If you want to talk about this thing called a wug then how do I talk about two of them? I put an S on the end, I have two wugs and then you can do this with other words as well.

So you can make up some verb and I’ll put a link in the video description box where you can see some children doing this where they’re given this new word they’ve never heard before like this is this is what it means to pell. You make up some word here, this is, I’m going to pell and then you say “What am I doing?” “You’re pelling”. Or “What did I do before?”. “You pelled.” This shows that the children actually understand all these grammatical rules for how to deal with different tenses even though, again, they haven’t had explicit instruction in this. Even though, of course, sometimes there are exceptions, this shows that they know the rule.

This wug test is evidence that even at age four or five children understand the rules of grammar in their native language. Now when it comes to the development of these rules of grammar, there is a time window and so this brings us to what’s called a critical period. The idea here is that children have to have exposure to the language before a certain time. So we have this biological predisposition to acquire language but it’s not unlimited, it has to happen while we’re young. It has to happen before sometime around age seven is the sort of estimate that we have.

Now how do we have this estimate? Well it’s through some unfortunate cases of children who are not exposed to language at all, who are deprived of a language environment. These are really terrible cases where children are raised in isolation and as a result they don’t develop linguistic fluency and if they are raised this way after the age of seven, or until after the age of seven, then their chances of developing full linguistic fluency decrease very sharply. So if a child is rescued from this type of environment at age five or six then they may be okay and they may be able to still acquire the rules of grammar but if they’re not rescued until later age 10 or something, then they aren’t going to be able to develop this full understanding of grammatical rules.

There’s some famous cases of this, perhaps the most famous is a girl named Genie, who was unable to acquire language because she was rescued too late and this critical period had already passed. We’ll look at another example of this idea of a critical period in the next video but the other part of this critical period is that if you’re exposed to a language before the age of 7 this equips you with the ability to process language and this can then be applied to other languages.

So when we talk about a critical period it’s important to remember that we’re talking about the first language. You have to have exposure to some language before the age of 7 in order for your brain to sort of learn how to process language but once you’ve learned one language you can then apply that to others and this is further support for this idea of universal grammar. If you understand how one language works you can sort of use that processing to figure out a new language even though the grammatical rules might be different.

So this isn’t applying to, it’s not saying that you can’t learn your second language after age 7, or your third or fourth or fifth, right? If you’ve learned a first language this equips your brain with the ability to process language and then you can apply that to other languages. Now it might not be easy, it might be a bit slower when it comes to acquiring that second or third or fourth language, but it is possible. Whereas if you’re not exposed to any language before the age of seven this means that you won’t be able to acquire grammar in any language.

Ok, so that’s the idea of a critical period and a little bit about how language develops in children. We’ll look at one more example this in the next video. I hope you found this helpful, if so, please like the video and subscribe to the channel for more.

Thanks for watching!