0:07 today we're going to talk about language development and one of the most fascinating questions of developmental psychology is how do babies cooing babbling babies transition from not knowing language to being able to understand words and actually combine them into simple sentences in such a short period of time in fact there is miraculous amount of growth in children's language skills over the course of the first three years there are actually three kinds of main language skills that researchers follow in young children the first is phonological development that is the ability to perceive and produce the sounds of one's language the speech sounds semantic development refers to words growing a vocabulary and
0:52 associating meanings with those individual words as well as meanings about the semantic relations between words for example if i said the cat blicked the dog even though you never heard the word blicked you would assume that was a verb the cat was doing something to the dog because you have grown in understanding relations among words and also grown in understanding how grammar works with words that leads us to grammatical development grammatical development is understanding the rules of syntax in a language how words are combined in meaningful ways to make sentences and this includes growing morphology growing tenses and so forth and what i mean by that is putting an ed at the end of a word
1:38 means it's a past tense putting an s at the end of a word in english refers to the plural and when we look at phonological development we know that newborns can hear all of the sounds of all of the languages in the world in fact the languages of the world have very different speech sounds hundreds of sounds and as adults we find it very difficult to discriminate speech sounds of other languages if we haven't been exposed to those but newborns can detect all of these here's a classic study you're looking at a graph of work done by janet verker and her colleagues and what they did is they exposed adults and babies to the language of thompson which has linguistic contrast of sound that
2:25 english speakers cannot detect of course thompson adults can so the gray bar on the left is showing you that all the thompson adults they had perfect detection of the distinction between these speech sounds but once you looked at english-speaking adults they did quite poorly that's the middle bar what's intriguing is that young babies were able to discriminate between the different speech sounds in thompson let's move on to semantic development semantic development is the production of first words at 12 months of age it has to do with when those words are being acquired and how vocabulary is growing so about the first year they get their first words and that's very slow and effortful it takes a long time for new words to enter the lexicon or vocabulary
3:11 but over time as kids hit about 50 words in development which is approximately 18 months for many english-speaking children in the united states there's what we call a vocabulary spurt there's a sudden growth in vocabulary where kids seem to be learning new words at a very rapid rate one of the features i should mention that enables them to learn at such a fast rate is this actual phenomenon of fast mapping they are able to now understand that words go together with objects in reference in the world just hearing a word maybe one time there was an original study that showed that toddlers if you presented them with two trays one was red let's say and one was a color they didn't know and the researchers said bring me the chromium tray kids right away realize that the
3:56 other tray of the color they didn't know must have been the chromium one with one observation or hearing the word one time so there's a phenomenon of very fast mapping and very fast language growth as children pass that early period of development and then they start putting words together they start combining words into very simple sentences those first simple sentences leave out small words like prepositions and they're very simple grammars like mommy eat rather than mommy is eating they have a lot of meaning they retain the grammatical order of words in the language in fact we know that if we look across many cultures research has shown a lot of similarities in children's vocabulary growth semantic growth across cultural communities mark bornstein and linda cote observed
4:43 the language vocabulary of 20 month old and they found that vocabularies of children across seven languages spanish dutch french korean english that children were very similar in the sizes of their vocabulary at that age and also all children showed more nouns in their vocabulary than verbs or adjectives which is a phenomenon that occurs because nouns have common shapes like the word ball is round and so it's easier to acquire words like nouns rather than verbs which are much more abstract nonetheless it's important to recognize that there's enormous individual differences in language development so in this figure you're actually looking at each line represents one child and this is lots of children who are immigrant children in the us dominican and mexican immigrants and as
5:29 you can see some children achieve 500 words these are kids at two years of age some of these toddlers had 500 words in their vocabulary and others had only five enormous variability even within immigrant populations in terms of grammatical development as i said the first sentences those are occurring around 18 to 27 months of age and then around 27 to 36 months that's when there's an explosion that's when all those little words and functions and past tense just start to seep into the sentences of young children that leads to the question this rapid growth in phonology semantics and grammar how are children acquiring language how are they able to determine the sentences of their language there are various theories about
6:15 language development skinner who is a behaviorist suggested that children learn through imitation and feedback from their environments that everything was kind of learned from positive or negative reinforcements but this idea has been critiqued because there's not always negative feedback to children if they produce the wrong grammatical structure like i a parent doesn't say no you didn't goad you went actually there's very little negative feedback and corrections of children's utterances and in fact children say a lot of things like his self gold sheeps they actually use words and constructions that are not found in adult speech so it can't be sheer imitation and sheer feedback chomsky proposed a nativist view which was that humans are innately equipped to learn language they have what he referred to as an lad
7:00 a language acquisition device we come born with a universal grammar and what happens is this language acquisition device with very minimal language input enables triggers the rule systems of that language so if in english you hear a lot of eds for past tense the language device triggers that and children acquire the rule from very minimal exposure and they don't need feedback others have criticized this idea that there's kind of a language acquisition device in the brain which we refer to as a top-down explanation for language and have argued that all you need is the input to actually build through statistical learning and understanding of how words work and how they go together statistical learning mechanism was proposed by jenny safran
7:47 many years ago in which she showed that if children heard certain syllables co-occurring quite a lot that would for them constitute a word so for example if you hear bad da ba da that is a reliable statistical regularity that always occurs together in the presence of an apple 100 of the time in in essence and so that high regularity enables children to learn what the word means there are a lot of social cues in the environment that help children figure out what the word is if i say blick it i point to it i look to it i pick it up and all of these social cues help babies discern what the word means until amanda woodward and
8:32 her colleagues actually engaged in a very fascinating study that is one example how toddlers can reach for objects and figure out which name goes to which object based on social cues such as eye contact and how they incorporate these many social factors into learning a word the socio-cultural view of language development and alternative idea is that we really need to understand how social context supports and promotes early language development especially the role of caregiver language input and interactions and this was proposed by people like vygotsky and jerome brunner now vygotsky proposes a sociocultural view he says that children are inherently social we interact with others in social settings and language is a psychological tool that creates this connection
9:18 and enables children to think and reason in new ways and adults share knowledge with their young toddlers and they socialize toddlers through language to be a part of their broader cultural community what are some of the supports what are some of the behaviors and parents that we know promote positive language and cognitive development they are reinforcement and stimulation reinforcing children who are approximating words ba and saying bottle visual cues to word reference pointing to the blicket as you say blicket reference matching parents labeling objects that are the focus of the child's attention linguistic contrast saying that's a cup not a glass so the child gets the distinction right before them between what's the difference between a cup and a glass
10:04 contingency labeling and naming and describing just as a child touches and acts on their worlds and engaging in learning activities such as book sharing where children have opportunity to be exposed to new words that they would not otherwise encounter in daily life is another way to promote language and then finally interactions with local materials and whatever those are in the environment and labeling those actually promotes learning in fact if we take a look at this figure this is showing the relation between children's growth over children's amount of language grammatically complex utterances related to parent's own grammatical complexity and you can see in this figure that as parents use more complex grammatical constructions so do their children those who use low
10:50 grammatical complexity so do their children and the same kind of linear trends have been found for vocabulary and so forth parents who use more words children acquire more words in their vocabulary so to summarize language of humans is astonishingly complex and it unfolds very rapidly in the first years of life children learn phonology semantics grammar and other cultural uses in an incredibly short period of time and there's this phenomenon in phonological development where there's perceptual narrowing there's a narrowing from being able to perceive all the sounds of all languages to channeling that and narrowing to the sounds of one's local language some of this has to do with the pruning that goes on in the brain and that's why
11:36 there's neuronal pruning to so the brain becomes specialized and finally parents and other caregivers and children's lives scaffold their language learning through various behaviors that support and teach children about their worlds you
