Inductive effects of head nodding and shaking motions on social decision-making

Abstract

Head nodding and shaking motions are important social signals that convey either agreement or negation to others. This study examines the inductive effects of the head nodding and shaking motions of three computer-generated three-dimensional figures （female, male, robot） on social decision-making between two alternatives. We employed a game task where participants had to determine the location of a coin hidden in one of two squares on either side of a central figure. When a participant clicked on one square, the figure would either nod or shake its head, then, after the participant clicked again to either stick with the initially clicked box or switch to the other, the squares would disappear to reveal the coin’s location. The results showed that second-click decisions were induced by the nodding or head-shaking motions of the central figure. Moreover, these inducing effects were observed regardless of figure type （young female, middle-aged male, robot）. These findings suggest that merely seeing nodding or head-shaking motions influences the evaluations and judgments that occur between actors and observers.