I'm no neuro-scientist or professor of psycholinguistics...but when Stephen Krashen and Steven Pinker personally tell me that someone is doing valid and important work then I listen and read on.

This is the paper by Dr. Patricia Kuhl of the Institute for Learning and Brain Sciences at the University of Washington in Seattle that caught my eye, 'a new view of language acquisition' which talks about how infants acquire language and how early learning is achieved in a purely social context and the evidence suggests, shapes the neural framework of the brain for language and communication. Using brain imaging bi-lingual babies often show up activity in two overlapping areas, one for each language. She concludes that first language acquisition could impair second language acquisition (i.e. previous learning could negatively affect later learning).

http://www.pnas.org/content/97/22/11850.full.pdf

I read it and saw mentions of 'social interaction', 'mapping' and 'multiple listenings' in infants and then  second language acquisition was mentioned towards the end. I pointed this out to Prof. Krashen. He sent me this further paper by Dr. Kuhl and Maritza Rivera-Gaxiola, 'Neural Substrates of Language Acquisition' and pointed me to a whole section on 'social learning':

http://ilabs.washington.edu/kuhl/pdf/Kuhl&Rivera-Gaxiola2008.pdf

Here are my comments on the paper (for what they are worth :-) and please bear in mind that I read from the LOT perspective, and a desire to get to the bottom of what happens when students use our materials.  I connect things, and maybe someone more qualified than I am would dismiss my connections outright.

Dr. Kuhl's experiment with infants, helping them to acquire Mandarin, is very similar in execution (as it is described by her) to what we do through our materials with adult learners.

I wrote this to Prof. Krashen:

'From Dr. Kuhl's paper you sent me:

"Infants heard 4 native speakers of Mandarin (male and female) during 12 25-min sessions of book reading and play across a 4–6 week period".

Our students speak to 5+ fluent or native speakers per lesson over a 25-30 minute period in the lesson and our courses last 4 weeks, sometimes a bit more.  Remember the stats I sent you from the first 700 students we taught?
http://www.languagesoutthere.com/articles/english-out-there-london-course-statistics-2001-to-2003

Here's the longer excerpt from the 'social interaction' section of her report:

"The impact of social interaction on speech learning was demonstrated in a study investigating whether infants are capable of phonetic and word learning at nine months of age from natural first-time exposure to a foreign language. Mandarin Chinese was used in the first foreign-language intervention experiment (Kuhl et al. 2003). Infants heard 4 native speakers of Mandarin (male and female) during 12 25-min sessions of book reading and play across a 4–6 week period. A control group of infants also came into the laboratory for the same number and variety of reading and play sessions but heard only English.Two additional groups were exposed to the identical Mandarin material over the same number of sessions via either standard television or audio-only presentation. After exposure, Mandarin syllables that are not phonemic in English were used to test infant learning using both behavioral (Kuhl et al. 2003) and brain (Kuhl et al. 2008) tests. Infants learned from live exposure to Mandarin tutors, as shown by comparisons with the English control group, indicating that phonetic learning from first-time exposure could occur at nine months of age. However, infants’ Mandarin discrimination scores after exposure to television or audio-only tutors were no greater than those of the control infants who had not experienced Mandarin at all (Kuhl et al. 2003) (
Figure 3). Learning in the live condition was robust and durable. Behavioral tests of infant learning were conducted 2–12 days (median = 6 days) after the final language-exposure session, and the ERP tests were conducted between 12 and 30 days (median = 15 days) after the final exposure session, with no observable differences in infant performance as a function of the delay"'.

And this is what I then sent to Dr.Kuhl:

"Hi Dr. Kuhl
 
Stephen Krashen sent me another paper by you ('Neural Substrates of Language Acquisition').  He pointed me to the social interaction section and it seems your experiment using Mandarin may have been close in its execution to what we do with our English language classes.  Our results are uniformly impressive as is the student feedback. See my email to Prof Krashen below. I'm also interested in Steve Pinker's notion of a deep metaphorical grammar that he discusses in 'The Stuff of Thought' and think that social interaction, showing and experiencing the language at the same time as listening to it, along with other stimuli, sight, smell etc. can improve SLA beyond what the methods most commonly used in language training achieve.  I'm also of the view that the recent (last two years) exponential increase in the numbers of learners using online social media and techonologies (IM/VoIP) (www.italki.com, www.livemocha.com ) could be the result of a growing migration towards what actually works.  The publishers didn't drive people there because no materials exist (except mine) but the numbers keep growing.
 
This is fascinating".

My notes in the margin of the paper are:

SLA in adults can probably be improved by tight focus, social use in multiple listenings + 'motherese' (naturally graded language in context?) + additional cognitive stimuli (sight, smell, taste, touch, emotion).

At the end of 'Neural substrates...' Dr. Kuhl asks this question:

"Which causal mechanisms underlie the critical period for second language acquisition - why are adults, with their superior cognitive skills, unable to learn as well as young infants? Can techniques be developed to help adults learn a second language?'

Dr. Kuhl has not replied yet, but I guess she's very busy. Steve Pinker said Dr. Kuhl was 'eminent' and kindly put me in touch with a Professor David Birdsong in Texas and we have started corresponding.

Maybe Dr. Kuhl doesn't want to reply to my main question which was along the lines of 'do you think that most published language teaching materials are any good?'.

I know, I shouldn't pile in (ask leading questions) like that.