What kind of physician would release such inconclusive and misleading results? This is a perversion of clinical medicine and academic rigor. The study had a small and homogeneous sample size, and the test subjects were unlikely to encounter the stimulus in daily life. Furthermore, the subjects were not tested before exposure to the stimulus, which means that there is no baseline against which to judge them. There was also no testing of effects lasting longer than a few minutes, making it difficult if not impossible to take any long-term action on this data.
I can't find anything about Dr. Christakis on the web besides his involvement with this issue. No curriculum vitae* (CV), no prior works, only a passing mention on the first hit of a search for his curriculum vitae on the CV of another man, Dr. Zimmern, who has connection to neither science nor medicine**. This research, however, is central to his (possibly current, there is no indication of a previous) idea of there being "good" and "bad" stimuli during early language development. His interests are clearly vested in the success and publication of this study.
In conclusion, though this man is not a quack, his methodolgy is poor and his claims poorly substantiated. The study is inconclusive at best and misleading at worst. This will play out over a long period of time, and there is much testing left to be done (and hopefully in a more rigorous way). It is too early to judge whether he is right or not, but he has a good incentive to be right.
-Penguin
*The only information on his education are a medical doctorate and masters of public health. He is also a Professor of Pediatrics, and a research affiliate in the Center on Human Development and Disability
**Dr. Zimmern is an economist with the education of: University of Notre Dame. B.A. Economics 1985
University of Wisconsin, Madison. M.S. Economics 1989
University of Wisconsin. Ph.D. Economics 1994