I have to admit I only stumbled upon this question due to the activity on Jeff Blaine's post. However, it did spark enough interest for me to do a little poking into the matter.
Honestly, I can't say there's nothing to it, but it hasn't exactly knocked my socks off so to speak. "Plausible but not conclusive" really gets to the heart of it.
Based on all I found, Baby Signs is based on some legitimate, if not terribly compelling research and seems to be another one of those "half-true" claims where a legitimate phenomena becomes exaggerated or misrepresented (either intentionally or unintentionally) in the process of marketing a product.
First thing's first: What we don't yet know about human language acquisition could fill a warehouse.
But that doesn't mean just anyone can fill it with nonsense.
The science behind what could make "Baby Signs" work (or not) crosses many disciplines, and as such can be hard to validate or refute. A full analysis of their system would require a knowledge of neurology, biology, neurolinguistics, and psychology among others. In short, if you haven't read at least Piaget, Chomsky and Pinker you should, otherwise the context of academic debate surrounding the research may be difficult to impart (as there is no way possible to cover it all at length).
How do babies learn language?
It seems to be a chicken-and-egg problem. You can't learn the language until you know the words. But you can't distinguish the words until you know the language.
Working with Jenny Saffran at the University of Wisconsin-Madison, and
Elissa Newport at the University of Rochester, Aslin has found one way
babies solve this dilemma: by using the pattern of sounds within words
to distinguish the ends of words. Babies "pay attention to sounds that
cohere within words, compared to the less predictive sounds that
change as they span a word boundary," Aslin says. And when that
pattern breaks, the baby understands that a new word is about to
start. source
I chose this example to illustrate the fact that some headway is being made, but much remains unknown, and while we may observe many correlations we have yet to fully understand the mechanisms at work.
Speech samples taken from seven firstborn children and their mothers
when the children were 1; 6 and 2; 3 were analysed within a number of
semantic and syntactic categories to determine correlations between
mothers' speech and subsequent language development. Several
characteristics of mothers' speech (e.g. utterance length, use of
pronouns) significantly predicted later child speech. The significant
correlations suggested that mothers' choice of simple constructions
facilitated language growth. Further, they showed that the motherese
code differed from adult-adult speech in ways which aided language
development. Differences between our study and previous investigations
of environmental effects on language development probably resulted
from the failure of earlier investigations to take into account
children's level of language competence at the time when environmental
effects were assessed.
This quote from journals/cambridge.org shows that when it comes to hard and fast data on language acquisition, we're really still just mining correlations and seeing what pans out. Science is if nothing else a gradual process, though.
The folks over at National Science Foundation voice the dilemma well...
How do children accomplish this remarkable feat in such a short amount
of time? Which aspects of language acquisition are biologically
programmed into the human brain and which are based on experience? Do
adults learn language differently from children? Researchers have long
debated the answers to these questions, but there is one thing they
agree on: language acquisition is a complex process.
In short, there is much we do not yet know about the psychological, biological, neurological, sociological elements of language, which is a large part of what makes it such a fascinating topic, as it cuts to the core of how we express ourselves and understand each other.
But as we're reminded, we don't yet have a solid understanding of how this works:
From Confounded Age: Linguistic and Cognitive Factors in Age Differences for Second Language Acquisition
What does Baby Signs Claim?
Even when viewed skeptically, it seems harmless enough, though I'll look at the MLM aspect later.
History of the claim: Just how legitimate is the research (and researchers) Baby Signs is founded on?
As to the request for study on this topic, there is actually quite a lot. More than previous answers would lead you to believe. A list of publications from Linda Acredolo (The seemingly more predominant academic of the two) can be found here. She has published extensively on spatial recognition and symbolic gesturing in children among other topics. To the best of what I can find as of now, her publications have all been fairly well received. Two of her more notable works with Goodwyn would be:
Acredolo, L. P., & Goodwyn, S. W. (1990). Sign language among
hearing infants: The spontaneous development of symbolic gestures.
In V. Volterra & C. Erting (Eds.), From gesture to language in hearing
and deaf children. New York: Springer-Verlag.
Acredolo, L. P., &
Goodwyn, S. W. (1990). Sign Language in Babies: The significance of
symbolic gesturing for understanding language development. In R.
Vasta (Ed.), Annals of Child Development (vol 7, pp 1-42). London:
Jessica Kingsley Publishers.
Which obviously laid the ground for the "Baby Signs" enterprise, and their findings do have some independent verification.
source
This idea seems to be validated by other sources including this from A Journal of the
Association for Psychological Science:
In development, children often use gesture to communicate before they
use words. The question is whether these gestures merely precede
language development or are fundamentally tied to it. We examined 10
children making the transition from single words to two-word
combinations and found that gesture had a tight relation to the
children's lexical and syntactic development.
And even though this lists Paul Ekman among its cited references, the paper seems sound:
This study found that the facial action of moderately or widely
opening the mouth is accompanied by brow raising in infants, thus
producing "surprise" expressions in non-surprise situations. Infants
(age = 5 months and 7 months) were videotaped as they were presented
with toys that they often grasped and brought to their mouths.
Episodes of mouth opening were identified and accompanying brow, nose,
and eyelid movements were coded. Results indicated that mouth opening
is selectively associated with raised brows rather than to other brow
movements. Trace levels of eyelid raising also tended to accompany
this facial configuration. The findings are discussed in terms of a
dynamical systems theory of facial behavior and suggest that facial
expression cannot be used as investigators' sole measure of "surprise"
in infants. source
Don't let the fact that this product is marketed toward cute, healthy babies distract you from an understanding of just how important research into language acquisition actually is....
While the idea of baby being able to wave a hand to alert mommy and daddy to the fact he's hungry or filled up the diaper again seems adorable, yet trivial....
Just consider some of the studies done with regard to hearing-impaired children, children with autism-spectrum disorder and children who have received cochlear implants and you can see how vital and emotionally charged an understanding of the dynamics of communication between parent and child actually can be, that's the real research this based on. Here are just a few....
Will They Catch Up? The Role of Age at Cochlear Implantation in the Spoken Language Development of Children With Severe to Profound Hearing Loss
Defining Spoken Language Benchmarks and Selecting Measures of Expressive Language Development for Young Children With Autism Spectrum Disorders
Spoken Language Development in Children Following Cochlear Implantation
Does a foundation in legitimate principles and valid research imply a claim to efficacy?
No. It doesn't. But no one makes the claim that Baby Signs is either guaranteed or effective. It only makes the claim that it is based on years of research, while leaving the reader to draw his/her own conclusions. They do offer a money-back guarantee I'm told (their people were very nice on the phone). After digging through the site, it seems most claims are made only by the slightest of implications and through videos of cute babies doing cute things. Even clicking on the "research proven benefits" link yields only this group of claims anyone could argue with until the proverbial cows come home:
Why MLM?
The MLM aspect of the business is always worthy of skepticism, however I haven't found complaints lodged with the BBB in the US, where the company is in fact highly rated and registered. Of course, that's only the parent company, and in a Multi-Level-Marketing Company the individual business "owners" shoulder the both the cost and liability, and a majority of those privateers associated with Baby Signs also seem to be in good standing in their various states:
some examples from Oregon and New Hampshire, a random sampling of states I checked (although if anyone else can check the other 48, and the other countries worldwide, I'd be interested to see what comes back).
I also found it quite difficult to find complaints against the company (from either customers or disgruntled multi-level marketeers) as you can easily do online with most MLM companies. So it seems while the company appears eager to capitalize on the enthusiasm of new parents, it also seems to do little to victimize them based upon it.
Does it work?
Unfortunately, after all that, the answer is.....maybe? Of the surprisingly few testimonials I was able to find regarding this product, one stood out to me, mostly because it read like the most beautiful, sweetly innocent version of confirmation bias I have ever come across, and I think while Baby Signs is based on research, this is what drives their sales and multi-level marketing:
After you have begun to sign with your baby, you may find that she is
making new and unusual gestures that you never noticed before. They
don’t quite look like the signs you have used with her, though you
must admit there may be a slight resemblance. You begin to experience
the first stirrings of hope and you think that maybe, just maybe, your
baby is signing. Just a Coincidence? As the parent of a baby, you
have likely witnessed your child as she tries out her new body,
checking to see what it can do. Younger infants, especially, will
sometimes test their range of motion by stretching, wiggling, and
flexing their limbs. It is for that reason that you may have trouble
believing that your child is actually signing. You may worry that you
will interpret her spontaneous movements as a deliberate sign.
The good news is that your baby probably is signing. At the very
least, she is likely trying to imitate the gestures she has watched
you make, even if she has yet to comprehend their meanings.
It is better to give her the benefit of the doubt and react as if you
are sure she is deliberately communicating with you. Acknowledge the
sign, and then give her what you think she may be asking for. If she
is signing, then you will be showing her that signing is a form of
communication. If she is not signing, she may still associate the
gestures with getting something she wants. This will take her one step
closer to actually signing. And if it turns out that she didn’t want
the object you thought she was asking for, she will undoubtedly let
you know it! source
