Dear Concerned in Cincinnati,
I would first like to commend you for investigating the practicality of your son's use of "baby signs" at daycare. By investigating this, you are proving that you would like to be proactive in your son's life. I understand your fear that by allowing your child to use nonverbal gestures to communicate he will find it unnecessary to make verbal progress. So as to ease your worries, I will explain some of the recent research on the subject of verbal and nonverbal communication, as well as the links between the two. A significant amount of research has shown that the use of "baby signs" in pre-verbal children actually has the opposite effect. Baby signs have been proven to actually help prompt the onset of verbal communication in children (Goodwyn & Acredolo, 1993). Unfortunately, many of the studies that have been performed to gain insight into this phenomenon lack generalizability due to the homogeneity of the children studied. A considerable majority of the children studied were Caucasian and from middle class families. This hinders our ability to apply the results of these studies to all children. This weakness aside, the research that has been conducted all supports that nonverbal gestures do not hinder a child's motivation to produce verbal language; in fact, these "baby signs" can actually support the development of oral communication.
One of the most important pieces of evidence in support of using baby signs is the conclusion of a different study conducted by Goodwyn and Acredolo in 2000. This study compared the amount of verbal language acquired by children who were encouraged by their parents.. In this study, the children in the group of interest were encouraged by their parents to use physical gestures to communicate. Two control groups were used. In one of these, no parental encouragement was implemented. In the second control group, however, parents encouraged children to use verbal language, and were unaware of the gestural language segway. What is interesting about this study is that the children who were simply encouraged to use verbal language acquired no more of a verbal repertoire than those who were not encouraged at all. The stars of this study were those who were provoked by their parents to use gestures. These children actually assimilated more words into their vocabulary during the study than those who were encouraged to do so. This study strongly supports your daycare's implementation of baby signs.
These studies, along with others should help to ease your worries about your son using baby signs as they have shown that – if anything, using these gestures will support his acquisition of verbal language. Another study by Blake, Vitale, Osborne and Olshansky seems to prove that gestures that could inhibit verbal language acquisition decrease with time and those that support it increase. This seems to be a way that children are naturally predisposed to verbal language. These factors, along with your encouragement should allow your child to develop language in a timely fashion. After reviewing all of the research, it is evident to me that no matter what you choose, your child is biologically inclined to produce language and than your support, as well as your son's care-provider's support will simply encourage this process to occur.
Goodwyn, S.W. & Acredolo, L.P. (1993). Symbolic Gesture versus Word: Is There a Modality Advantage for Onset of Symbol Use? Child Development, 64, pp. 688-701.