Baby Sign Language: What is it good for?

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Baby sign language is very popular these days. There are classes and online resources and it’s all based on the premise that signing with your baby introduces a host of benefits from better communication to long-lasting language advantage. A very recent study done by a group of researchers from Hertfordshire University put the premise to the test, and examined the effects of baby sign language on language development.

What they did

The authors recruited forty 8-month-old infants and their mothers, and randomly assigned each mother-infant dyad to one of four groups: a) British Sign Language training (for mothers); b) symbolic gesturing system (gestures adapted from baby-signing courses) training; c) "verbal training" (the mothers got the instructions to use the same words as the mothers in the other two groups, but there was no signing information); and d) no intervention at all. The design is beautiful. The researchers even made sure that the same words were used in all the "treatment" groups, and they assigned the same number of female and male infants (5 and 5) to each group, to control for the known gender effects. I particularly like the fact that they had not one, but two control groups (verbal training and no intervention). They followed up on the kids until the kids were 20 months old, and called the mothers every two weeks to do a phone interview (and probably mostly to remind them to use the signs).

What they found

The authors report that there was no effect at all of the intervention. The authors write: "The overall language development of all infants was similar regardless of the intervention that they experienced." (pp. 579). Infants in the intervention groups acquired the target words a little earlier than the children in the no-intervention group, but that seems to be the extent of the impact of treatment. The authors conclude that there is no benefit to encouraging baby signing, at least when it comes to language development.


Here is my problem with this beautifully designed study: they had 40 infants total in their sample. That's a very small sample size. In general, effects in child development tend to be small – there are a lot of factors in play, and no one thing determines something as complex as a child's language skills. From a statistics point of view, the smaller the effect, the larger the sample you need to see it in the data. I ran the math, and their chances of detecting a small effect were 12%. In other words, there very well may be a small effect of using sign language with babies, but that in this study the sample was not big enough to detect it. Now, it's true that this probably means that there is no huge benefit to signing from a language point of view. But the authors make it sound like there is no point at all: in talking about mothers who sign up for baby signing classes and such they say, "the efforts of these mothers may be unnecessary." (pp. 586).

My two cents

I personally think there is a huge difference for the mother and for the mother-baby communication when using signs. I didn't use signs with my son until he started daycare. When he started daycare (he was 9 months old and did half-days for a couple of months) he started signing because he learned it from the daycare workers. They taught me some of the signs, and it made the communication so much easier. He could say what he wanted – not everything he wanted, obviously – and I could see it was making him feel "empowered". Not being able to communicate, by the way, is one of the main sources of frustration and tantrums in the second and third years of life (and why toddlers are so "terrible"). To me, preventing tantrums is most definitely a benefit of using signs with babies :)

Did you use signs with your baby? Did you find it helpful?

@2015 - Gal Podjarny