Teaching babies sign language may help with learning spoken language

A few weeks ago, an article appeared in my local newspaper. According to the article, many mothers were beginning to teach their kids sign language, starting at a very young age. Both kids and parents had perfect hearing, but the babies learned sign language even before they could speak, communicating more effectively with their parents about basics like needing a diaper change or a favorite toy. I was immediately skeptical: what about learning spoken language? If babies could communicate effectively with signs, what incentive would they have to learn the language the rest of us speak?

Susan W. Goodwyn, Linda P. Acredolo, and Catherine A. Brown (of Cal State Stanislaus, UC Davis, and San Diego State University) had been investigating sign language for years, but they suspected the opposite. Based on their research on children of hearing-impaired parents, they expected that when babies learned sign language, they would be motivated to learn spoken language as well. To test their hunch, they conducted an impressive longitudinal study ("Impact of Symbolic Gesturing on Early Language Development," Journal of Nonverbal Behavior, 2000).

Controlled longitudinal experiments are the gold standard for developmental research. By comparing two or more groups of children as they change over time, researchers can learn how different environments affect them as they grow older. Other studies may compare children of different ages at a single point in time, but in these studies, it's difficult to pinpoint the precise factors that lead to the differences between individuals.

Goodwyn and her colleagues compared three groups of babies from the age of 11 months to 36 months. In the control group, the parents were not told that language development was being studied, and the children were raised as they normally would be. In the second group, parents were encouraged to teach babies signs to represent common items in their lives. These were not formal American Sign Language signs, but just any signs the parents might make up in order to commenicate with their babies. In the final group, parents were asked to make special efforts to teach spoken words to their babies, but were not instructed at all to use any kind of signs.

The purpose of the third group was to ensure that any language effects in the signing group were due entirely to the use of signs: it's possible that language any language improvements in signing babies are simply due to the fact that they have been trained. Babies who are explicitly offered spoken language training might improve just as much as those with sign language training.

But Goodwyn and her colleagues found that the spoken language training group was statistically the same as the untrained in language ability at each point in the study. By contrast, the sign gesturing group showed not only the ability to learn a large array of signs, but they also demonstrated superior spoken language skills in five different measures compared to the untrained group.

Babies showed the largest differences at the age of 19 and 24 months, where the sign-trained group scored significantly higher in tests of receptive language—how well they understood spoken words. At 15 and 24 months, the sign-trained babies outperformed the untrained babies on expressive language tests measuring how well they spoke.

So not only do babies trained in sign gestures show better spoken language skills, but they are able to communicate in signs much more effectively than they would have been able to without training. What kind of things do babies say with their increased signing abilities? Here's a small sample from the article:

One other important implication of this study is that the verbal language improvements for the sign-trained babies were not permanent. At 36 months, the trained babies were indistinguishable from the control group. So what benefits do sign gesture training offer for parents? Goodwyn and her colleagues argue that the process is worth it simply for the quality of life improvements it offers during the toddler years. As a parent who's lived through those years, I concur: trying to communicate with a toddler can be frustrating enough to induce balding. Just one example from the article is particularly telling:

A 16-month-old, who awoke crying in the night, was able to point and use his "afraid" gesture (patting his chest) to let his mother know he was afraid of the clown doll on his dresser. Without the gesture, she might have put the doll in bed with him!

This example reminds me of several late nights where a bit more communication might have helped both father and child sleep a lot more peacefully.