Baby signs boost IQ by 12 points

[Brian MacWhinney]

Dear Info-CHILDES,

      During the flurry of discussion of the C/P contrast, there was  
an message from Mechthild Kiegelmann that seemed to slip under the  
radar screen.  This message summarized replies to a query about Baby  
Signs.  I spent some time tracing the various web links involved and  
I would like to draw colleagues' attention to one issue in this  
research that troubles me.  This is the status of a report by  
Acredolo and Goodwyn, which is cited prominently at www.babysigns.com  
and www.signingtime.com (STResearch_Summary.pdf).  This reports  
speaks of a 12 point "increase" in IQ measured at age 8 for children  
who are taught Baby Signs when they are toddlers.  Interestingly,  
Mechthild's links also point to an article from the Canadian Language  
and Literacy Research Network by J Cyne Johnston, Andrée Durieux- 
Smith, and Kathleen Bloom that challenges the claims of this study by  
noting that it provides no description of subject recruitment  
provedures, attempts at random assignment, or evidence of any  
pretesting.  They conclude that, "The high accessibility of a wide  
range of baby signing products is not matched by good quality  
evidence that would reinforce manufacturers' claims."
       It is worth adding that the groups were already different when  
the Bailey was given at 24 months, but this is presented not as  
evidence of initial group differences, but rather as the result of  
the initial effects of the treatment.  The relevant study was  
presented as a conference paper at ISIS in 2000, but has never been  
published in a journal.
    I have mixed feelings about the plausibility of this result.  I  
certainly do not view IQ as immutable and genetically-given.  I am  
also quite convinced that Baby Signs provide an excellent method for  
achieving early and rewarding communications with toddlers.  However,  
I find it difficult to believe that a program in Baby Signs alone  
could achieve a 12-point increase in IQ when several years of Head  
Start lead to nothing measurably permanent.
    I hope that academic researchers take these unpublished claims  
with a healthy grain of salt.  If there are newer studies supporting  
these claimed gains in IQ, I would love to learn about them.

--Brian MacWhinney, CMU