Tuesday, September 09, 2008

Critical Period

Dammit, that title is entirely functional and contains no puns or weird allusions whatsoever. I'm off my game on these Ask Paca answers.

Today's question comes from a long time reader, known to all of you only as WrittenWyrdd. I happen to know that she's actually Tyra Banks, supermodel, but I'm not supposed to tell. Tyra, I mean Wyrdd's question is:

I'm curious about language learning windows, myself. Regarding the hardening of the palate and other physical speech issues, where is the optimum time to learn languages like Chinese with sounds we do not make in English from a physical standpoint crossed with the optimal brain stage? Do these cross at all? I seem to recall that theory used to have the optimal periods were very young for the brain, but once the palate hardened up, so did the brain's wiring. Sort of.

Again, entire books could be, and have been, written about this. There's only one fact that we know for sure and that people of all different theories agree to: Children learn any language they are exposed to sufficiently, while adults have much greater trouble. But exactly what causes this additional trouble and just how strong or important it is is hotly contested every few days.

In one school of thought, language is some sort of cognitive organ or something in your mind and it develops on a biological schedule just like other parts of your body develop along a rather set plan. Your language organ (this is really the term) gets set by puberty at least and it doesn't change. And therefore the way that people do learn new languages as adults is completely different than they do as kids. As kids, it's part of a natural biological process. As adults, it's a general puzzle or skill that you have to pick up like taking up knitting or learning to rebuild a car or something.

In another theoretical framework, people argue there's no real biological timetable, but instead people just become set in their ways with their first language, and this first language just can't get out of the way to allow you to pick up the new pattern. In grammar, you might speak English first in which the basic sentence word order is subject verb object. But then you try to learn German or Korean, which has subject object verb, and you just can't get your mind to flip. That's grossly simplifying, but you get the idea.

Either way, the period in which language seems to come easily is typically called the critical period. After that, you are out of luck.

One problem with all of this is that it's not clear that people really are out of luck. There are many adults who move into another nation or culture with a different dominant language, and they live their for 40 years, with only 20 in the 1st language, and they still clearly speak with a huge accent, limited vocabulary, odd syntactic patterns and phrases, etc. But there are also adults who move as adults to another nation and really pick the language up quite well. I've certainly met people who learned English at least only starting as a teen, and it's hard to tell it's not their first language. (Though of course also when you get to know someone as a person, you often stop hearing any accent at all; I only hear my parent's southern accents when they are on answering machines, but rarely in person.) Some number of adults are actually still quite good at language.

Moreover, compare how a child learns to speak with how an adult does. The classic American way to learn a language is to show up in a class for 3-5 hours a week, maybe have another 3-5 hours of homework, and then ignore the language as much as possible in between. In between everything you do uses language 1. Compare this to a child. Anyone who's had a young one knows that they NEVER SHUT UP. All day long, they practice their new language. Every meal, during the movie, when you're on the phone, watching TV, in the car.... They truly seem to practice their language all. the. time. When they aren't speaking, they are thinking, and often we think in our language. I've known a couple people who were language sponges. One of them did the semester abroad in China with me. She started out, having just taken one summer course, and left after 5 months at least on the 3rd year level. But she studied Chinese all the time. I'd be doing nothing on the bus to some tourist site, and she'd be there reading the dictionary. While I was shy to meet people that I couldn't talk to on the train and sat with my friends or read a book, she'd wander straight into the "hard seat" compartment and talk to Chinese people for hours on end.

Regardless, languages for adults are still harder in general than for children who are still in the "critical period". And while no one agrees on why this is the case, it's certainly mental/neurological in some manner.

But that's not quite what Tyra asked. She asked about the palate hardening up and whether that affects the speech sounds we can make. Honestly, I've never heard of that. I typed a couple Google searches in and didn't come up with anything. While I imagine the palate in infants can harden up, I'm guessing it's not really all that important to language. To review anatomy for others, the roof of your mouth is divided into two palates, the hard palate in the front closer to and above the teeth, and the soft palate, which is actually a fleshy muscle behind it. The hard palate is covered cartilage and is immovable. The soft palate (also called the velum) is soft and fleshy and moves. If you run the tip of your tongue from the teeth back touching the roof of the mouth, you will feel the hardness change to softness at some point. It also might tickle a bit. All of us have unconscious control over moving the soft palate up and down, but we often only gain conscious control by taking a phonetics course and practicing.

In speech, both palates are used to make sounds. In both English and Chinese, you make lots of sounds by arranging your tongue in different positions along the palate. The [sh] sound of English is made by bringing your tongue right to the front of the hard palate. A [g] sound is made by touching your tongue to the middle of the soft palate. In both of these examples, and all sounds in between, the palate doesn't do anything. It just sits there, and by moving your tongue, you create different acoustics in your mouth.

The soft palate, however, is movable, and we take advantage of that in speech. The soft palate can be raised to close off the passage way to your nose or lowered to open it up. Both Chinese and English have [n]s, [m]s, and [ng]s which are all nasal sounds, so called because you make them by lowering the velum to let air go through the nose. You raise it up for everything else, so that air only goes out of the mouth.

You can see all of this in action by watching this X-Ray of a phonetician speaking. Notice the big white thing flapping up and down in the back. That's the soft palate. You will see the tongue approaching the hard palate most clearly on words with the [ee] sound.


And so I can't see how a hardening palate would affect speech development. I can certainly imagine that a newborn's hard palate isn't yet hard, but newborns don't speak. It would have to be still soft until around one to two years old for it to be relevant to actual speech production. But even in adults, the hard palate doesn't do anything other than be there. One would have to come up with an argument that language actually shapes the palate itself during development. And all such accounts would run up into at least two facts 1) children who start a new native language at 4 or 5 learn the language just fine. This age would be long after any palate hardening and yet still long before the critical period passes. Also, 2) there are many native bilinguals of Chinese and English (meaning neither is a second language for the person; they are both first languages).

Finally, the problem that people typically have in producing new speech sounds isn't that they can't make the sounds individually. Certainly, they will have problems with it on day one, but after some time, they can produce each individual sound pretty decently. It's stringing all the sounds together. I can get a decent South African click to come out of my mouth, but ask me to put a click into a whole word with a bunch of other sounds, and I fall apart. I think this again points to the critical period being a mental thing, even for weird speech sounds, more than a physical thing.


Mommy to Ander and Wife to Box said...

Good question and excellent answer.

Ello said...

I can't believe I followed all that and it made sense! Paca I think you are making me smarter!

Ello - who is actually Cindy Crawford.

writtenwyrdd said...

She-who-is-not-Tyra says Hah! My college professor told me wrong! He was an English prof, granted; but I would have sworn the man knew what he was talking about. There was something about in your early 20s the palate hardens so some sounds become practically impossible--such as the rising and falling tones of Chinese--unless you learn them before that point.

Fascinating stuff, paca. Thanks for taking the time and trouble.

pacatrue said...

I'm glad the explanation wasn't horrible. And I'm glad that both Cindy Crawford and Tyra Banks read my blog.

Wyrdd, I can't figure out what he was saying. My guess is that he had something else in mind as the palate from the way the term is used now. But as for tones, yeah, that don't make no sense. Tones are just controlled pitch changes made by tensing and laxing your vocal folds. Every healthy person has this ability in every language. That's not to say that tones are easy for an English speaker. They most certainly are not. But the troubles are again mental / neurological.

By palate, he'd have to be referring to something in the brain. The neurons won't get harder, but they do become wired in certain ways, making certain skills hard to develop. For instance, beginning learners of Chinese largely process tone in their right hemisphere in areas associated with music and other general pitch patterns. Chinese speakers process tone in the left hemisphere in more language-related areas. It's that sort of thing which can become "hard".

writtenwyrdd said...

Well, perhaps he had some screwy data, but I am positive he said the palate hardens and that's what makes learning certain sounds difficult. I have wondered at that over the years because I can learn how to make new language sounds, even though learning langages isn't the snap it was when I was younger!

Still not Tyra...

writtenwyrdd said...

Rereading that it sounds as if I'm trying to contradict you. Not. I figure you know your subject.