at low risk. Research Iverson's early research explored the role of gesturing in communicative development in individuals who were blind from birth and aimed to answer the question of why people gesture. Iverson and Susan Goldin-Meadow tested two possibilities that were not mutually exclusive. First, speakers may gesture simply because they see others gesture, and learn from this model to move their hands as they talk. To test this, they studied spontaneous gestures in congenitally blind children and adolescents and a control group of sighted children and adolescents. Second, speakers may gesture because they understand that gestures can convey useful information to the listener. To test this, they examined whether speakers gestured even when talking to a listener known to be blind, and thus obviously unable to profit from information conveyed by gesture. The researchers found that gesturing did not depend on either a model or an observer and appeared to be essential to the speaking process itself. Their findings suggest that the gestures that accompany speech may reflect or even facilitate the thinking that underlies speaking. In a longitudinal study of children at ages 10 to 24 months old, Iverson and Goldin-Meadow examined how children's early gestures support their acquisition of first words and the transition to two-word speech. Using video-recordings of naturalistic observation of caregiver-child interaction, the researchers coded instances of speech or gesture, or a combination of the two. They found that children often referred to objects using gestures prior to acquiring the corresponding words. The child's identification of a referent through gesture both preceded and predicted their learning of its name. Iverson and Goldin-Meadow also found that children's use of a gesture in combination with a word (e.g., pointing at bird while saying "nap") predicted their subsequent production of two-word combinations, such as "bird nap", when the gesture provided information that supplemented the meaning of the word. These findings suggested that gestures and words are tightly linked in early communicative development. With Esther Thelen, Iverson explored how gestures and other body movements may serve as a foundation for language development. They found that hand and mouth are mutually activated by spontaneous hand/mouth reflexes in newborn infants. Further, by the time they are 16 to 18 months old, infants produce meaningful words and gesture combinations in synchrony. Building on work by David McNeill that views gesture and speech as generated by a unified system for communicating, Iverson