Answer: We know that “language development” does not actually only refer to the development of verbal language - in fact, there are a number of typical “milestones” leading up to the emergence of verbal language, or, in the case of a child using alternative methods of communication, leading up to expressive language through an augmentative communication system. The use of symbolic gestures, or gestures to represent a specific object, action or thought, for instance, typically emerges from around 8 months (Bates & Dick, 2002; Capone & McGregor, 2004) to 10 months of age (Goodwyn, et al, 2000) and continue to be highly utilized through the age of 18 to 24 months (Bates & Dick, 2002; Capone & McGregor, 2004; Clements & Chawarska, 2010), when the verbal equivalent usually takes its place or is added to the gesture (Acredolo & Goodwyn, 1985, 1988; Goodwyn et al, 2000). There is even evidence to suggest that the more symbolic gestures a young child uses, the larger their vocabulary is by the age of 24 months (Acredolo & Goodwyn, 1988; Goodwyn et al, 2000). When a parent or caregiver is modeling use of gestures—representational gesture (so, for instance, waving to represent a greeting of hello or good-bye), referential (for example, pointing to refer to that object over there), or another type of gesture, whether in routines, in play, or in song, the child is being taught additional ways to communicate. They are communicating by labeling objects, relaying information, acknowledging, requesting objects, actions or information, or even requesting social routines, such as a song. Whether or not we model gestures that are part of a system of symbols, such as American Sign Language, the gesture provides a concrete way for that young child to express him or herself before (or during) the emergence of verbal language. The research out there indicates that, as Goodwyn et al. (2000) write, “the symbolic gesturing experience seems to ‘jump start’ verbal development.” A 2016 study (Barker, 2016) suggests that this finding applies to children who are developing along a typical progression as well as those with communication delays.
Answer provided by: Ayelet Marinovich, M.A., CCC-SLP, of Strength in Words