I Once picked my nose ‘til it bleeded. Child Language Acquisition in

How do children learn to speak their native language? The answer to this question might seem obvious. They just copy their parents, right? Not so fast. Consider, for example, the following sentence spoken by Simpsons’ TV Anchorman Kent Brockman “And the elephant that couldn't stop laughing was put to death” (The Frying Game). Did Brockman learn this sentence as a whole from a parent, or, for that matter, from anyone else? Clearly not. Rather, he learned from his parents, and other native speakers, both the individual words and some kind of abstract rules or sentence patterns that allow these words to be put together to convey particular meanings. Explaining just how children do this is the goal of language acquisition research. There are essentially two possible answers. The first (e.g., Chomsky, 1957; Pinker, 1984) is that children are born with some empty categories (e.g., [NOUN] and [VERB]) and some basic rules for combining them into sentences (e.g., one possible sentence type consists solely of a [NOUN] and a [VERB]; e.g., (the) elephant laughed). On this view, children’s task is simply to fill in these pre-existing categories with words that they hear, and to find out which particular version of the sentence-construction rule applies in their language (e.g., is it [NOUN] then [VERB], like in English, or [VERB] then [NOUN] like in some other languages?). The second possible answer (e.g., Braine, 1963; Tomasello, 2003) is that children must build these generalizations from scratch on the basis of the language that they hear. For example, a child who heard The elephant laughed, The man shouted and The dog barked might abstract across these strings to build what is known as a slot-and-frame schema (e.g., The [PERSON/ANIMAL] [ACTION]ed); a pattern that allows entirely new sentences of the same form to be generated (e.g., The woman danced). The first approach is known as the nativist approach, because it stresses the importance of categories and rules that children are born with (a native of a country is someone who was born there; the nativity is the story of the birth of Jesus). The second approach is known as the constructivist approach because children instead construct these categories and rules from the language that they hear. In this chapter, we will compare and contrast the nativist and constructivist explanations for some of the major phenomena in language acquisition, on the basis of examples from The Simpsons.

Lisa’s First Word: Word Learning.

In the episode Lisa’s First Word, we discover the first word spoken by each of the Simpson children: “Aye Carumba” (Bart), “Bart” (Lisa) and “Daddy” Maggie (Daddy is actually the most common first word, slightly edging out Mummy; Fenson et al, 1994). But just how do children learn words? There are two basic problems. The first problem is finding where one word ends and the next begins (a problem that – in a roundabout way – is the source of Bart’s chalkboard gag “I will not scream for ice cream” in Lisa Gets an A). Unlike written text, speech doesnthavegapsinbetweenthewords. So how do children split up the stream into words? One nativist answer (e.g., Gambell & Yang, 2005) is that they are born with the knowledge that each word contains no more than one stressed syllable. So, for example, even the first time we heard his name, we knew that the bartender was called Moe/Syzslak and not MoeSyzs/Lak (Bold=stressed syllable, /=word boundary), because the latter would violate this rule by having two stressed syllables, Moe and Syzs, in the same word. One constructivist answer (e.g., Saffran, Aslin & Newport, 1996) is that children keep track of how often one syllable follows another, and assume a word boundary whenever a very rare combination turns up. So suppose Maggie hears herself described as a PRI-TY-BAY-BE (pretty baby). She can tell that the correct way to slice up this stream is PRI-TY/BAY-BE and not PRI/TY-BAY-BE, because the combination PRI+TY is quite common (and so probably a word) whilst the combination TY+BAY is extremely rare (and so almost certainly not). The debate between the rival accounts is ongoing. The first account works well in computer simulations, but is hard to test on real children. The second works well with children, but only with very artificial made-up languages. The second word-learning problem is figuring out what each word means. Say, for example, that Maggie hears someone Snowball as the cat walks past. How does she know that Snowball is the name of the cat? It could just as well mean “furry”, “tail”, “look at that”, and so on (Quine, 1960). One nativist answer (e.g,. Markman & Wachtel, 1988) is that children are born with assumption that new words label whole objects rather than properties (“furry”), parts (“tail”) and so on. The problem with this answer is that many words don’t label whole objects at all (e.g., party; the), so this assumption would actively hinder children much of the time. A constructivist answer (e.g., Tomasello, 2003) is that children understand what speakers are trying to do with their language, particularly when this language is part of familiar routines. For example, if Marge and Maggie often play a “naming game” together, Maggie will understand that when Marge says “Snowball” she is naming the cat rather than saying, for example “look at that”. A problem for this answer is that children seem to learn some words when they are just a few months only, and so probably unable to understand speakers’ intentions in this way.

I Once picked my nose ‘til it bleeded: Morphology

In Natural Born Kissers, Sideshow Mel, upon seeing Homer float past, exclaims “Look at that blimp…He is hanging from a balloon”. But if Mel were to recall the incident later, he would have to say “He was hanging from a balloon”. Similarly, in The Simpsons Spin-Off Showcase, “Lisa” sings a song called “I want candy”. But if she were singing about past candy-cravings, she would have had to sing “I wanted candy”; or, about someone else, “He wants candy”. The use of either whole words (e.g., is, was) or bits of words (e.g., - ed, -s) to indicate tense (e.g., past vs present) or the person that we’re talking about (I want vs He wants) is called morphology (and the words, or word-bits, morphemes). When learning systems of morphology, children typically make four characteristic mistakes. The task of theories of child language acquisition is to explain exactly why they do so. The first common mistake is to miss out these morphemes altogether. For example in the episode Trilogy of Error, when Lisa’s grammar robot, Linguo dies, Homer cries in alarm “Lingo…dead”. With its dying words, the robot corrects him, “Linguo is dead”. The most common nativist explanation (e.g., Wexler, 1998; Legate & Yang, 2007) is that children do this because they think that marking tense is optional. That is, they think you can include the “is” if you like, but, if you can’t be bothered, that’s fine. This isn’t as crazy as it might sound. First, there are lots of words that are optional, for example the “that” in Homer’s description of a dancer in Mayored to the Mob, “I think (that) I saw him in Rent or Stomp or Clomp, or some piece of crap”. Second, there are many languages in which speakers don’t mark tense at all. A speaker of Mandarin Chinese really would say (the equivalent of) “Lingo dead”, and it would be up to the listener to work out whether he meant is dead, was dead, will be dead etc. The problem for this account is that it can’t quite explain why these errors are much more common in some languages than others. The rival constructivist explanation (e.g., Freudenthal et al, 2007) is that children hear adults say things like “Is Linguo dead?”, store these sentences and re-use them, missing off the start of the sentence “Is Linguo dead”. This explanation works well for most languages, but doesn’t predict why English children make this error quite as much as they do (around 90% of the time for most 2- year-olds). The second common mistake that children make is using the wrong morpheme. This mistake is quite hard to see in children learning English, so I’m going to have to hope that, like Bumblebee Man (who is actually Belgian; see Simpsons Comic #110), you have learned just a little Spanish. Imagine that a Spanish child wants to say “They play” (talking about a group of people). The correct thing to say is “Ellos jeugan”, which has the plural (“they”) ending –an. But what Spanish-learning children often do (Aguado-Orea, 2004) is to use the singular (“he”) ending –a and say “Ellos jeuga”. As I said, this mistake is quite hard to spot in English, but the nearest equivalent would be something like the Italian mobster Louie’s “They’s throwing Robots” (Lingo: “They are throwing robots”). So why do sometimes children use the wrong morpheme? The nativist answer is basically to argue that they don’t (ignoring the very occasional slip of the tongue). This is because the nativist account assumes that children are born already understanding how systems of morphology work, and so should rarely trip up. And, indeed, it is true that – overall – these errors are pretty rare. The constructivist response is to point out that children make these errors quite often with rare forms (like juegan), which they can’t remember, and so substitute a form that they’re much more familiar with (like juega) instead. The third common mistake that children make is over-applying morphological rules to words that are actually exceptions to the rule. For example, one particularly well- studied rule is that English verbs form their past-tense by adding –ed (e.g., play/played; walk/walked etc.). Some verbs are exceptions to the rule (e.g., bleed/bled), but children often go ahead and apply the rule anyway, resulting in utterances such as ’s “I once picked my nose ‘til it bleeded” (The Dad who Knew Too Little). The nativist answer is that children are born with a default-rule (“add the thing that – in your language – is the regular marker”) that steps in whenever children can’t remember the correct irregular form (e.g., Pinker, 1999). A problem this account is that it can’t explain why, when applying the –ed rule is the correct thing to do, children are better at doing it with some verbs than others (e.g., Marchman, 1997; Ambridge, 2010). The constructivist answer is that children are misled by analogy similar-sounding verbs (e.g., “If it’s need/needed, it must be bleed/bleeded”). The problem for this account is that, although it generally fails rather well, computer models that learn to produce past-tense forms by analogy with similar-sounding verbs never reach the very low (basically 0%) error rates shown by adults and older children (Ambridge & Lieven, 2011). In Burns’ Heir, Bart tries to persuade Mr Burns to make him his heir by reciting a speech (written for him by Homer) that contains the claim “Me sick”. This sentence gives us two errors for the price of one: (a) missing out the “is” (the first type of error we met in this section) and (b) – the fourth and final type of error that we will examine here – using the wrong form of a personal pronoun, in this case “Me” instead of “I”. Children make these errors quite often, saying “Me” when they mean “I” (e.g., “Me do it!”), “Her” when they mean “She” (e.g., “Her eat it”) and – more rarely – “Him” when they mean “He” (e.g., “Him is happy”). The nativist answer (e.g., Wexler, 1998) is that every language has a “default” form of each personal pronoun; the form that you use when there’s nothing else in the sentence to guide you (for example, you would say “Me too!”, not “I too!”). The motivation for this explanation is that the concept of a default form is again something that children are argued to be born with. The constructivist answer (e.g., Freudenthal et al, 2007; Kirjavainen et al, 2009) is that, just like for the first type of error in this section, children are storing sentences that they have heard from adults and missing off the first word (e.g., Let me do it à Me do it). A problem for these accounts is that children seem to make the errors more often than would be predicted by either. This suggests that, whatever else may or may not be going on, children are simply mixing up the two words in each pair. They know that both Me and I refer somehow to themselves and that She and Her refer somehow to females, but don’t understand why you must sometimes use one alternative, and sometimes the other (Rispoli, 1994; Ambridge & Pine, 2006).

He card reads good: Basic Word Order

We have already encountered the scene in Burns’ Heir, where Bart tries to persuade Mr. Burns to make him his heir by reading an error-filled speech written for him by Homer. Oblivious to the numerous errors in the speech, Homer proudly says to Marge “He card reads good”. In order to focus on the issue we’re interested in here, we’ll overlook the debate over whether Homer should have said “well” instead of “good” (“good” is probably fine in colloquial American English), and pretend that he said “cards” instead of “card” (this does seem like an error, just not the one we’re interested in here). So, what we’re left with is this:

What Homer (nearly) said: He cards reads good What Homer should have said: He reads cards good

Why is the first wrong and the second right? The answer is that English follows [SUBJECT] [VERB] [OBJECT] word order. What this means, oversimplifying quite a bit, is that the person who does the action (the [SUBJECT]) comes first, then the action (the [VERB]), then the thing that has the action done to it (the [OBJECT])

SUBJECT VERB OBJECT

He reads cards (good)

Homer’s mistake involves using – instead of the correct [SUBJECT] [VERB] [OBJECT] word order – the order [SUBJECT] [OBJECT] [VERB].

SUBJECT OBJECT VERB

He cards reads (good)

But here’s a thing: Some languages do use this SUBJECT OBJECT VERB (SOV) word order. In Turkish, for example, (the equivalent of) He cards reads would be right, and He reads cards wrong. So how do English-speaking children learn that their language uses SVO word order, whilst Turkish children learn that their language uses SOV? The nativist answer (e.g., Gibson & Wexler, 1994) is that children are born with a kind of mental switch called a parameter. This switch has two settings: OV (the English- type setting) and VO (the Turkish-type setting). Children have to listen to the language around them in order to figure out which setting to flick the switch to. Once they’ve done that, the rules of sentence construction that children also born with kick in, and they’re away (actually, they also have to flick another switch with settings of SV and VS, but we’ll ignore that since very few languages have the VS setting). The problem with this account is the idea that children can figure out whether to set the switch to SV or VS by listening to the language around them. If words came with labels on them saying “VERB” and “OBJECT” this would be easy. As soon as an English child heard – for example – close[VERB] the door[OBJECT] – she could flick her switch to the VO setting. But obviously, words don’t come with these labels (for one attempt to solve this problem, and a critical response, see Pinker, 1989, and Ambridge, Pine & Lieven, in press, respectively). The constructivist alternative (e.g,. Tomasello, 2003) is that children aren’t born with these rules or parameters at all and, instead, build generalizations on the basis of the language that they hear. For example, suppose that a child hears and stores the strings I’m eating it, I’m hitting it and I’m kicking it and abstracts across these to form an I’m [ACTION]ing it slot-and-frame schema. Suppose further that the same child hears and stores the strings Mummy kissed Daddy, Daddy Kissed Mummy and Mummy kissed the baby and abstracts across these to form a [KISSER] kissed [KISSEE] slot-and-frame schema. The final stage requires children to notice some similarity between these two schemas. For example the relationship between I and [eating/hitting/kicking] - a kind of doer-action relationship – is kind of parallel to the relationship between a KISSER and kiss. The idea is that this similarity allows children to align and analogize across the two structures to form a more general [DO-ER] [ACTION] [DONE-TO] pattern that is basically equivalent to a [SUBJECT] [VERB] [OBJECT] rule. The problem for this account is that nobody has yet conducted a study which demonstrates that children are able to perform this abstract leap of reasoning (except for domains other than language- learning; see Gentner & Medina, 1998). This is not to say that there is no experimental evidence for or against either account more broadly. In fact, there is loads (e.g., see Ambridge & Lieven, 2011; 209- 242 for over 30 pages of it). Obviously, it is not possible to summarize all of these findings here, but what it boils down to is the following: Evidence for the constructivist approach comes from findings that most of children’s earliest utterances – both in experiments and more naturalistic settings - look as if they could have been generated using low-level slot and frame schemas (e.g., I’m [ACTION]ing it) (see Tomasello, 2000; Ambridge & Lieven, in press, for reviews). Evidence from the nativist approach comes from findings that even very young children (i.e., 1-2 years) appear to know something general about SVO word order (Gertner, Fisher & Eisengart, 2006; Noble, Rowland & Pine, 2011). For example, if they hear a sentence such as The duck is glorping the bunny and are asked to point to the matching video from a choice of two, most correctly choose a video where a duck is doing something to a bunny, rather than one where a bunny is doing something to a duck (note that “glorping” is an invented word for an invented action, in order to prevent children using their knowledge of familiar verbs to solve the task).

And the elephant that couldn't stop laughing was put to death: More advanced sentences

Theories of child language acquisition must be able to explain not only the bread-and- butter phenomena of single words and simple sentences, but also more complex sentence types such as passives and questions. We have already met one passive sentence “And the elephant that couldn’t stop laughing was put to death”. How did Kent Brockman learn to produce sentences of this type (as we have already seen, he certainly did not learn them directly from his parents). The nativist answer starts with the observation that for each passive sentence, there is an equivalent active sentence (in order to focus on the issue at hand, it will help if we simplify the sentence a bit, including – sorry – replacing the euphemism “put to death” with the much more straightforward “killed”).

Active: The vet killed the elephant Passive: The elephant was killed

The child starts out with the phrase “killed the elephant” and generates the passive sentence by “moving” the thing that has the action done to it (the elephant) to the start of the sentence (and inserting was)

The elephant (was) killed the elephant

This is a nativist account because the idea is that the child is born already knowing this movement rule. All she has to do is discover whether or not movement happens in her language – it doesn’t in some – much like setting word-order parameters (see above). Evidence for this account comes from studies showing that even very young children are good at producing passives in some circumstances (e.g., Bencini & Valian, 2008). The constructivist alternative is that children again schematize across sentences that they hear (e.g., It got hit by it; It got killed by it; It got broken by it) to form slot-and-frame schemas that they can use for their own productions (e.g., It got [ACTION]ed by it). The evidence for this view is that children show best performance when asked to produce passives for which these schemas can be used (Savage et al, 2003). Questions come in two different flavours. Yes/no questions are questions that expect a Yes or No answer; for example Agent Scully’s question to Homer in The Springfield Files: “We’re going to ask you a few simple yes or no questions. Do you understand?” (Homer answers “Yes”, which causes the lie detector to explode). Wh- questions use a wh-word (who, what, why, where, when or – an honorary wh-word – how [much/many etc.]). For example, in Homie The Clown, Krusty asks his devoted audience the wh-questions “Who do you love?” (“Krusty”), “How much do you love me?” (“With all our hearts”) and “What would you do if I went off the air?” (“We’d kill ourselves”). According to nativist accounts, questions – like passives – are also generated using innate movement rules; for example “Who do you love” from “You (do) love who?”

Who do you do love who?

Again, the evidence for this account is that children – overall – make relatively few errors in their naturalistic speech (e.g, Stromswold, 1990), though questions with do are a bit of an exception, often showing higher error rates. The constructivist alterative is – yet again – that children build up slot-and-frame schemas (e.g., What are you [ACTION]?) by schematizing across suitable frames that they hear (e.g., What are you eating/reading/doing? etc.). Again, the evidence for this account is that children show their best performance when they can potentially use one of these question schemas (e.g., Rowland, 2007; Ambridge & Rowland, 2009), and sometimes make errors when they cannot. Many children struggle with negative questions and ask – for example – Why can I can’t have some? (instead of Why can’t I have some?), presumably because negative questions – and hence the opportunity to form a suitable slot-and-frame pattern – are rare in the input.

Summary

This brief review has contrasted nativist and constructivist accounts of children’s language development across four central domains, using examples drawn from The Simpsons: Word-learning (Lisa’ First Word), morphology (I once picked my nose til it bleeded), basic word order (He Card Reads Good) and more advanced sentences (And the elephant who couldn’t stop laughing was put to death). What ties these domains together is that, in every case, the nativist account starts from the assumption that children are born with something that helps simplify the learning task - whether (a) assumptions about how words work (b) a default-rule in morphology (c) word order parameters or (d) movement rules – whereas the constructivist account does not, instead arguing that – in every case – children build up slot-and-frame schemas from the language that they hear. Nativist theorists take low overall error rates and children’s generally impressive (and fast) language learning as evidence for the view that we must all be born with some knowledge that gives us a head start. Constructivist theorists take unevenness – i.e., higher rates of correct performance when children can potentially use a slot-and-frame schema than when they cannot – as evidence for their view. Obviously attempting to evaluate these two views in their entirety is well beyond the scope of a short introductory chapter (for one attempt to do so, see Ambridge & Lieven, 2011), but it is my hope that this chapter has at least encouraged some readers to explore further this (to me) fascinating debate. We began this chapter with a question: “How do children learn to speak their native language?” and dismissed – with the help of an example from TV’s Kent Brockman – the idea that children might simply memorize all the sentences that they will ever need. Instead, we saw that what children must actually do is to use the language that they hear to abstract rules or sentence patterns that they can they use to produce entirely new sentences. In other words, and to borrow another classic Homerism (from ‘Round Springfield), children are like jazz musicians “They just make it up as they go along”.

References

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