Mothers modulate their gesture independently of their speech

Do speakers alter their gestures independently of speech during communication? We addressed this question by examining how mothers modulate their speech and gestures when communicating about safety with their children. Mothers and their 8- or 10-year-old children viewed and discussed a series of images depicting another child engaged in a variety of physical activities with the goal of deciding on a joint safety rating for each image. When mothers perceived a situation as more unsafe than their child did, they conveyed more information in both speech and gesture. Importantly, as this disparity between mother and child ratings grew, mothers systematically increased their rate of gesturing when communicating dangerous information and decreased their rate of gesturing when communicating non-dangerous information. These findings show that speakers selectively alter their gestures for their listeners, demonstrating that speech and gesture need not be modulated in parallel.