reading the signs: the evidence on baby sign language

What's the deal with baby sign language? When did families start using it, and does it have positive effects?

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The first research investigating baby sign language (BSL) took place in the 1980s (we’ll get to that in a minute), but BSL really became a phenomenon in the 90s. In the twenty-first century, not only is there a huge market for BSL products, it’s used all over the place--not just in individual family homes. Daycare centers sign. Pediatric offices encourage it. It’s on TV and the internet. It’s in the news. It’s everywhere.
          And the claims about its possibilities are equally far-reaching. BSL can teach your child to speak sooner; increase your child’s IQ and cognitive development; reduce tantrums; boost self-esteem; alleviate parental frustrations; improve bonding. Heck, even the American Academy of Pediatrics (AAP) came out in 2012 to say that BSL “helps improve communication.”[1] All of this sounds pretty wonderful, of course, but let me be clear at the outset: none of the alleged claims about BSL’s benefits have a shred of evidence behind them. So where did this idea even come from? Let’s briefly take a closer look:

Researchers first became interested in studying baby signing pretty recently, in the 1990s, after they recognized that some babies with deaf parents (who signed) seemed to benefit in their speech development. The (uncertain) finding prodded scientists to explore whether the same advantages might extend to children with hearing parents. They hypothesized that a true “baby sign language” would promote and advance infant language development.[2] As it turns out, they were wrong. 
          Almost all the early research on baby signing emanated from two scholars: Susan Goodwyn and Linda Acredolo. The duo’s most comprehensive project was published in 2000. It followed about 100 babies and reported that babies who learned signing displayed advantages “on the vast majority of language acquisition measures.” The results, Goodwyn and Acredolo concluded, “strongly support the hypothesis that symbolic gesturing facilitates the early stages of verbal language development.”[3]
          But besides being subject to very legitimate criticisms for scientific procedures (more on that in a second), the advantages Goodwyn and Acredolo found were modest. At best. More importantly, any differences they documented had already disappeared by the time children were 1.5-2 years old. [4]  Even the duo itself clarified: “significant positive effects [of BSL] do not appear to last.”[5] (We might harbor some concerns, too, that Goodwyn and Acredolo have strong ties to the BSL industry: they authored a popular book on BSL (Baby Signs) and run a corresponding business that trains BSL instructors. Nonetheless, their enthusiasm does appear genuine. I don’t hold it against them…that much.)
          The BSL studies—conducted by Goodwyn and Acredolo as well as others—suffer many weaknesses, methodologically: few are randomized or controlled; all have small sample sizes (some are very small—just a handful of children); most fail to explain participant selection, procedures, and group allocation; they don’t verify the extent to which infants even learned gestures; and they are thus subject to selection bias.[6] And virtually all the work that has come out on BSL in the last 20 years runs counter to both Goodwyn and Acredolo’s findings and the broad cultural mindset that champions BSL as a stimulus for infant development.
          One of the first reviews to assess BSL came out in 2005. It looked at 17 studies on signing babies between 1980 and 2002, and concluded that “the existing research was methodologically flawed and, because of this, there was ‘no evidence to suggest that Baby Sign had any benefits for child development.’”[7] Subsequent projects suggest the same.
          A really interesting study (in 2012) assessed claims made on more than 30 BSL websites. The authors performed one of my all-time favorite types of analysis: footnote-tracking. Lauri Nelson and her team followed the citations for every single claim about the benefits of BSL on these websites, and found that more than 90% of citations were opinion pieces. Opinion articles can be useful and informative, of course, but they are not data. They are not evidence. This means that a mere 10% of BSL “benefits”—just 8 citations—had any grounding in empirical research whatsoever. Furthermore, zero of the claims about fewer tantrums, improved self-esteem, and heightened parent-child bonding had any kind of evidence base, be it opinion or scientific. Nelson’s final words to parents: “decisions about whether to teach sign language to their young children with normal hearing must be based on opinions and beliefs but not on research.”[8] Two years later, in 2014, fresh reviewers lamented that “the pace of scientific contributions to understanding [BSL] is relatively poor,” and concluded that there is no evidence substantiating that BSL improves communication development in young children.[9]
          A more recent study tells us more. Babies were randomized to either learn to sign or not (a third group received verbal training to control for the instructive component of BSL), and researchers evaluated the babies’ language development periodically over the course of a year. “While the babies learned and used the signs (often before they could speak),” lead researcher Elizabeth Kirk reported, “doing so made no significant impact on their language development.” Babies who signed didn’t start talking sooner or faster. Parents’ efforts to teach babies to sign, Kirk concluded, “may be unnecessary.” Other projects have corroborated these results, all amounting to the same takeaway: we don’t have any evidence that indicates BSL is beneficial or advantageous for babies’ development.[10]
          Anecdotally, some parents even worry that baby signing detracts from verbal language development because babies have less impetus to speak, and their cognitive faculties are being used up for signing. In other words, since they can already effectively communicate with signs, and a great deal of their mental energy is devoted to signing, signing babies might be less compelled to develop language skills. There’s no science to support this, but the issue frequently arises with parents, enough so that media pieces set out to set the record straight: “Can Baby Sign Language Delay Speech?” one article asked. (No, it concluded.)[11]
 
To my mind, the most interesting aspect of baby signing really has to do with parent-child interaction. (In formal research lingo: the “wider non-linguistic impact of encouraging infant gesturing upon the dyadic interaction between mothers and infants.” Whew.) In short, BSL proponents claim that signing facilitates better parent-child relationships. This strikes me as a logical argument, even if science doesn’t offer us much data to support it. Indeed, results assessing quality of life measures are “inconclusive,” and some even suggest that enrollment in formal signing education programs might actually instigate parental stress.[12] 
          That said…find me a family that thinks signing wasn’t a boon to its connections, that was unhappy with signing. (I’ll wait.)
          Just because we don’t have any convincing evidence that BSL expedites babies’ development doesn’t necessarily mean that it isn’t useful, or even beneficial. It certainly isn’t harmful. (None of the projects assessing BSL have ever documented any detrimental outcomes with BSL. As one 2014 review concluded: there is no evidence to suggest that BSL is “effective,” but nothing indicates that teaching BSL impacts development.[13]) There’s just a lot we still don’t know (or can’t measure). Here are a couple things we do know:

• A LOT of parents love baby signing. Seriously, parents are crazy for it. I’ve never met or heard of anyone who was disappointed with it…And in fact, we actually do have some research to support parents’ devotion to baby signing: parents tend to respond and interact more with babies who gesture (this doesn’t have to be formal BSL—it applies to any babies making simple gestures, such as pointing). It stands to reason, then, that parents who teach their babies to sign might be forging more interactive time with their children, and that’s never a bad thing.[14] Put simply: we shouldn’t overlook the fact that many families simply really enjoy signing. That’s worth something.

• Babies learn by interacting with the world around them--hence, the whole “Einstein-never-used-flash-cards” philosophy.[15] And we also know that: babies benefit from early, frequent, and variable exposure to language, as well as when adults talk with them, as silly as that might seem.[16] It all comes down to interaction. Since the ability to gesture is intricately linked to language development, it isn’t unreasonable to think that teaching babies to sign is contributing to overall learning (and/or communicative development).[17] Again, no evidence doesn’t necessarily mean no dice.

 
So where does this leave us? I think it depends on parents’ purposes and expectations for signing. Parents who see BSL as an avenue for enhancement—something that will give their child a leg up in terms of brain development or IQ or vocabulary…a means to an end—are probably going to be disappointed (at least that’s what the data says.) But parents who see BSL through a more relaxed lens—as a way to begin communicating before babies start talking, or as a fun activity to engage in together—just might love it. And when it comes down to it, even the most invested advocates of BSL express this same moderate take: the “right” reason to do any level of BSL (it’s not an all-or-nothing undertaking, of course) has nothing to do with IQ or cognitive development or language acquisition. It’s simply a “nice activity” for families to do together.[18] (And do we really need science to tell us as much?)

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[1] Elizabeth M. Fitzpatrick et al., “How HANDy Are Baby Signs? A Systematic Review of the Impact of Gestural Communication on Typically Developing, Hearing Infants under the Age of 36 Months,” First Language 34, no. 6 (December 1, 2014): 488, https://doi.org/10.1177/0142723714562864; Michael Alison Chandler, “Baby Sign Language More Popular as Parents Aim to Communicate,” Washington Post, July 28, 2013, sec. Education, https://www.washingtonpost.com/local/education/baby-sign-language-more-popular-as-parents-aim-to-communicate/2013/07/28/6ad114a4-f0a4-11e2-9008-61e94a7ea20d_story.html; Lauri H. Nelson, Karl R. White, and Jennifer Grewe, “Evidence for Website Claims about the Benefits of Teaching Sign Language to Infants and Toddlers with Normal Hearing,” Infant and Child Development 21, no. 5 (September 1, 2012): 474, https://doi.org/10.1002/icd.1748.
[2] Elizabeth Kirk et al., “To Sign or Not to Sign? The Impact of Encouraging Infants to Gesture on Infant Language and Maternal Mind-Mindedness,” Child Development 84, no. 2 (April 2013): 575, https://doi.org/10.1111/j.1467-8624.2012.01874.x; J. Cyne Johnston, Andrée Durieux-Smith, and Kathleen Bloom, “Teaching Gestural Signs to Infants to Advance Child Development: A Review of the Evidence,” First Language 25, no. 2 (June 1, 2005): 237, https://doi.org/10.1177/0142723705050340.
[3] Susan W. Goodwyn, Linda P. Acredolo, and Catherine A. Brown, “Impact of Symbolic Gesturing on Early Language Development,” Journal of Nonverbal Behavior 24, no. 2 (2000): 81, 98, https://doi.org/10.1023/A:1006653828895.
[4] Fitzpatrick et al., “How HANDy Are Baby Signs?,” 501.
[5] Goodwyn, Acredolo, and Brown, “Impact of Symbolic Gesturing on Early Language Development,” 101.
[6] Kirk et al., “To Sign or Not to Sign?,” 575; Johnston, Durieux-Smith, and Bloom, “Teaching Gestural Signs to Infants to Advance Child Development,” 242–43.
[7] Elizabeth Kirk, “Baby Sign Language: Does It Work?,” Discover, February 4, 2015, http://blogs.discovermagazine.com/crux/2015/02/04/baby-sign-language-work/#.WhNeaRNSyqQ.
[8] Nelson, White, and Grewe, “Evidence for Website Claims about the Benefits of Teaching Sign Language to Infants and Toddlers with Normal Hearing”; Kirk, “Baby Sign Language: Does It Work?”
[9] Fitzpatrick et al., “How HANDy Are Baby Signs?,” 505.
[10] Kirk, “Baby Sign Language: Does It Work?”
[11] Victori Clayton, “Can Baby Sign Language Delay Speech?,” msnbc.com, June 6, 2005, http://www.nbcnews.com/id/8060750/ns/health-childrens_health/t/can-baby-sign-language-delay-speech/; Goodwyn, Acredolo, and Brown, “Impact of Symbolic Gesturing on Early Language Development,” 94; Chandler, “Baby Sign Language More Popular as Parents Aim to Communicate.”
[12] Fitzpatrick et al., “How HANDy Are Baby Signs?,” 505–6; Kirk et al., “To Sign or Not to Sign?,” 581.
[13] Fitzpatrick et al., “How HANDy Are Baby Signs?,” 487, 507.
[14] Fitzpatrick et al., 487.
[15] Kathy Hirsh-Pasek and Roberta Michnick Golinkoff, Einstein Never Used Flash Cards: How Our Children Really Learn-- And Why They Need to Play More and Memorize Less (Rodale, 2003); Patricia Kuhl, “Baby Talk: How Babies Learn Language,” Scientific American, November 2015, https://doi.org/10.1038/scientificamerican1115-64.
[16] Cari Romm, “Pretending to Understand What Babies Say Can Make Them Smarter,” The Atlantic, August 29, 2014, https://www.theatlantic.com/health/archive/2014/08/pretending-to-understand-what-babies-say-can-make-them-smarter/379324/.
[17] Jana M. Iverson and Susan Goldin-Meadow, “Gesture Paves the Way for Language Development,” Psychological Science 16, no. 5 (2005): 367–71; Gwen Dewar, “Baby Sign Language: A Guide for the Science-Minded Parent,” accessed November 21, 2017, http://www.parentingscience.com/baby-sign-language.html.
[18] Carla Kemp, “Sign Language Touted as Way to Help Infants Communicate Early On,” AAP News 19, no. 2 (August 1, 2001): 54–54.