When Jim was a baby (back when we called him "Jimmy"), he was clearly a bright child, but he didn't have a lot of words. This didn't stop him from getting his point across. After his doctor recommended that we cut back on the bottle to encourage him eating solid foods, he'd repeatedly say one of his two words: "bah-pull." When the desired result wasn't achieved, he pulled us by the hand into the kitchen and pointed to the item he craved (cf. Orangutans playing charades).
Within a few months, however, Jim knew dozens of words and was even assembling some primitive sentences. What accounted for the change? A Scientific American article may offer some answers:
Cognitive scientist Bob McMurray of the University of Iowa set up a relatively simple mathematical model of word learning on a commonly available spreadsheet, assessing the potential to learn each of some 200 words. He set a numerical threshold at which a given word would be considered learned, operating under the assumption that it would take kids time to learn each word, they could pick up multiple words at the same time, and that some words were more difficult to process.
The results matched up with our experience with Jim:
Running the actual mathematical model, McMurray found that toddlers inevitably experienced an explosion in word learning after a set period of time, no matter what. Initially, the most common words are learned relatively slowly followed by a rapid jump in vocabulary. In other words, a little girl might know only the most often heard words at 12 months but a short four months later be able to command several hundred words that she only hears occasionally.
But how, exactly, are these words being learned? Companies like Baby Einstein want to sell you DVDs and other devices to help kids learn faster. But a new report being discussed widely suggests that these products don't help and may actually harm language acquisition. Here's what LiveScience has to say about the study:
What's new is the finding that so-called educational and brain-development products can have not just a neutral but reverse effect, delaying speech development because the baby is robbed from interactions with real people.
"There is no clear evidence of a benefit coming from baby DVDs and videos and there is some suggestion of harm," said Frederick Zimmerman, lead author of the study. "We don't know for sure that baby DVDs and videos are harmful, but the best policy is safety first. Parents should limit their exposure as much as possible."
I don't know of much evidence that delays in language development are especially harmful, so the net effect of taking longer to learn words may not be great. And as McMurray's research points out, eventually there's going to be an explosion in language learning. But it's interesting to note that the very products that are being sold as "genius-makers" may be having the opposite effect.
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What particularly bothered me about that research study was the definition of "hard" words. A quote from the article:
"Anytime you have more difficult than easy words [the learning curve] will have this property."
Is it "harder" for you to hear some words? Do you have to try especially hard when listening to a particular word? Perhaps you may think harder if the context is difficult, but the actual soundwave of one word verse another is not "harder" or "easier" to understand. The article, however, specifically states that contextual learning is shenanagins and "working on the margins".
To a developing infant, it would appear all sensory input is essentially the same. We have yet to find any special organ that has genetically encoded linguistic abilities. It appears infants bootstrap their language abilities themselves, of course how is the debate.
I doubt it is due to the "hardness" of a word though. The sound from the word "mom" is roughly similar to the sound "automobile", and really is about the same as the sound from a real automobile. It is all sensory input that the infant is attempting to discriminate from. One is not more tasking to listen to than another.
I'm not saying that the leap in linguistic ability is not similar to the mathematical curve presented in the article. But the article suggests that the linguistic leap is precisely because of the math. They suggest math is causing the leap, not the leap causing the math. I think this is a fundamental flaw that nullifies any good conclusion from the study, other than "this curve can easily represent language abilities". Which could be deduced from a lot of data and some excel spreadsheets.
But perhaps I'm just being overly critical :)
Zachary Tong, if I'm reading it correctly, the study's definition of a "hard" word is one that takes more time to learn. For whatever reason. They explicitly assume some words are harder than others, by that definition, but they aren't making assumptions about whether that's because some words are heard less often than others, or because some phonemes are more difficult to process, or because some words have more phonemes to process, or whatever. I think it's a reasonable definition of "hard." You might complain about the assumption that some words take more time to learn than others, but I think you'd be on shaky ground.
(I may have interpreted incorrectly. The article is not completely clear.)
"Hard" words, at least in linguistics, are those that are more syntactically complex, usually those that are bound by context (see left v. right, here v. there, etc.). It's much easier for the child to learn nouns, basically creating mental labels for the objects surrounding them (nouns make up over 60% of the child's first hundred words). These nouns are normally the words affected by the process of fast mapping, the phenomenon at the center of the study you posted, and it's been found that a child has these words in their lexicon after less than 5 exposures.
At any rate, I think the answers to these questions will be found through cognitive studies before mathematicians have much to say about it. That study is nice and descriptive I guess, but it doesn't provide any kind of answer to any kind of unsolved problem as much as I can tell. The question is really in the cognition, and what it is about the developing brain that allows us to acquire a native language with absolute proficiency regardless of mental ability, not discovering the statistical distribution most able to map the progress of vocabulary building. The question isn't how Jim's vocabulary exploded, but why Jim is able to ask a properly phrased question or state a correctly-inverted negative.
Great news! Now I know that Baby Einstein DVDs, which contain virtually no talking whatsoever, can't teach language. Thanks, Science!
"delaying speech development because the baby is robbed from interactions with real people"
Right. So in other words the "conclusion" of Zimmerman is not supported. There may be no harm of watching BabyEinstein (given the real Einstein's checkered development/formal schooling history I'm not sure why one would choose this name...) just so long as the interactions with "real people" remain the same and/or sufficient. no? Likewise, if bad parents are going to ignore their kids one way or another, wouldn't watching BabyEinstein be a possible upgrade from watching the ceiling lying in the crib???
I'm with dietcoupon (#3) on this one.
The phenomenon does indeed sound like fast mapping. Further (in support of the basic idea behind the study reported), some words are easier to fast map than others. Two processes that appear to affect word acquisition speed: (1) social experiences (e.g., Western children grasp nouns faster; Eastern children grasp verbs faster--both apparently due to the extent to which such words appear in the speech of adults); (2) development of more general cognitive processes (e.g., theory of mind and stages of cognitive development as outlined by Piaget) which are likely to impact speech pragmatics, which in turn is necessary for grasping words associated with more abstract ideas (e.g., modifiers--big, small; short, tall, etc).
I'd bet the inevitable bell-shaped pattern described is due to a transition between concrete and abstract word learning, whose pattern is governed by the processes suggested in #2 (a pattern, interestingly, that looks much like that of the pattern concerning the formation of neural development in many brain regions).
It might not be too surprising that the Baby Einstein product has a negative influence if it somehow negatively impacts speech pragmatics (e.g., removing the social interaction critical for fast mapping).
EJ, dietcoupon: Oh, apologies for the tirade. I wasn't aware there was a distinction of "hard" words in linguistics. I guess it does make sense as some words are much more abstract than concrete words like "dog", where you can see the word running around licking your face. Guess I should do my homework next time before commenting :)
Actually, "automobile" can be considered more complex than "mom" in terms of learning to speak. If you look at both these words being spoken using a spectrogram, you will see that they are quite different and that automobile is much more complex. A child will probably recognize the word automobile long before he can say it, while he has been saying "mom" for quite some time. The "fast mapping" and word acquisition studies I believe are all measured by words children actually say, not ones they recognize.
Furthermore, sensory input is not the only requirement needed for a child to speak. They need to have a reason. Baby Einstein is not as exciting as Mom or Dad's attention.
"Great news! Now I know that Baby Einstein DVDs, which contain virtually no talking whatsoever, can't teach language. Thanks, Science!"
Really? How about the "Baby Einstein Language Nursery Digital Board Book DVD"
for ages 1 mo to 4 years?
Considering that the DVD's are sold to increase the cognitive development of babies then it is indeed news that they don't do this.
One of my friends when I was a teenager expressed an interesting idea -- that rate of learning depends on having "hooks" in place that you can hang ideas/details off of. At first there are only a few previously-understood concepts that you can attach knowledge and understanding to. Where those aren't, trying to acquire detail is like trying to hang up a coat on a smooth wall. It just slides off. As you acquire concepts, however, they build in all directions, with a lot of projecting surfaces...where further concepts can "stick" properly.
The first step of language acquisition seems to be nouns, but the basic concept that goes with this may be something like "this specific sound always stands for this thing, and I use it to communicate the contents of my thoughts to people who can do something about it". Nouns are the easiest because they are physical objects which can be pointed to, but the concept that goes with it opens up a surface to which words for feelings and actions can be attached, and that opens the door to things like expressing causality and asking questions. As soon as the smooth wall has hooks in it, more and more things can get hung there at once. Make sense?
Luna, the "hook" concept does have some validity based on my observations of working with language disordered children. Some chidren have difficulty learning language because they cannot associate auditory, visual, tactile,kinesthetic or affective cues to language in a typical way. So if they are not getting the the precise input they need, then they are not learning words fast enough. There can be a mismatch between parents and child, or the child can have a disorder that needs to be addressed through therapy. For example, I showed a female patient a picture of a child crawling. The patient could not say that the child was crawling. Then I asked, "What do you call it when you get down on your hands and knees and move?" She still could not answer. Then I told her to get down on her hands and knees and move around. I said "What do you call that?" She said, "Crawling."
That's interesting. So a connection is not being made between "this is me doing this" and "this is the thing and that word always means the thing"?
Well, I believe that she learned best when she moved her body (i.e., kinesthetically), so the motion of crawling helped her brain access her word storage. She already "knew" the word, but could not recall it until the motion helped her. The photograph and my description together were not enough. In other words, her "hook" was not as sturdy as a typical child's hook and needed reinforcement.
The Seattle Post-Intelligencer has been covering Disney's response to the University of Washington study that initiated the Baby Einstein news. So far, the UW is standing up to Disney's strong-armed tactics to have the press release 'corrected' or withdrawn. If you are interested in reading more, I've put a summary of the situation on my blog.
@Ann -- ah, I see what you're saying; the hook between vocabulary and physical world had to be reinforced. Still interesting!
My son was implanted with a cochlear implant at age 1 so he missed that entire first year of sound. When we began using his implant, he was mapped incorrectly and the sound he heard was distorted and made no sense.
From the time he was implanted to about 3 months ago ( about 3 years ) his lexicon was extremely limited to simple monosyllabic utterances. He could chain together a couple of words but sentences and understanding of relationships was very difficult.
Then all of the sudden he was chaining together 5 and 6 words with articles intermingled. He learns words now after hearing them once or twice. His language has just been expanding so rapidly. I constantly hear him saying new things that I had no idea he had learned.
It is one thing to observe a studies data and understand its implications. It is quite another to experience your child going through this large scale change in their internal semantic models.