traced the developmental origins of the gesture–speech system through studies of vocal–motor coordination. She and a colleague focused on 6- to 9-months infants and how certain gestures of the upper extremities might underlie the coordination of speech and gesture apparent in adults. They found associations between rhythmic movements of the arms (especially the right arm) and increased rates of babbling. The authors suggested that "When an infant is engaged in an intense bout of rhythmic limb activity, for example, the level of activation in the motor system may spill over into the vocal system and entrain its activity." Thus, on account of manual control developing more rapidly than vocal articulation, voluntary limb movements may serve to help infants gain voluntary control over their vocalizations. Selected publications Iverson, J. M. (2010). Developing language in a developing body: The relationship between motor development and language development. Journal of Child Language, 37(2), 229–261. Iverson, J. M., & Goldin-Meadow, S. (2005). Gesture paves the way for language development. Psychological Science, 16(5), 367–371. Iverson, J. M., & Goldin-Meadow, S. (1998). Why people gesture when they speak. Nature, 396(6708), 228. Iverson, J. M., Northrup, J. B., Leezenbaum, N. B., Parladé, M. V., Koterba, E. A., & West, K. L. (2018). Early gesture and vocabulary development in infant siblings of children with Autism Spectrum Disorder. Journal of Autism and Developmental Disorders, 48(1), 55–71. Iverson, J. M., & Thelen, E. (1999). Hand, mouth and brain. The dynamic emergence of speech and gesture. Journal of Consciousness Studies, 6(11-12), 19–40. References External links Faculty page Infant Communication Lab Pittsburgh Early Autism Study American women psychologists 21st-century American psychologists Developmental psychologists University of Pittsburgh faculty University of Missouri faculty Bryn Mawr College alumni University of Chicago alumni Living people Year of birth missing (living people) American women academics 21st-century American women