Impact of symbolic gesturing on early language development

The purpose of the present study was to evaluate the effect on verbal language development of purposefully encouraging hearing infants to use simple gestures as symbols for objects, requests, and conditions. To this end, 103, 11-month-old infants were divided into three groups, all of whom were seen in the laboratory for a variety of assessments, including standardized language tests at 15, 19, 24, 30, and 36 months. Parents of those in the Sign Training group modeled symbolic gestures and encouraged their infants to use them. Parents of infants in the Non-intervention Control group knew nothing about symbolic gestures or our special interest in language development. As a control for "training effects" (i.e., effects attributable to families being engaged in a language intervention program), parents of a second control group of infants (the Verbal Training group) were asked to make special efforts to model verbal labels. After comparisons of the two control groups minimized concerns about training effects, comparisons between the Sign Training and the Non-intervention Control group indicated an advantage for the Sign Training group on the vast majority of language acquisition measures. These results provide strong evidence that symbolic gesturing does not hamper verbal development and may even facilitate it. A variety of possible explanations for such an effect are discussed.