Spontaneous gestures during mental rotation tasks: insights into the microdevelopment of the motor strategy.

This study investigated the motor strategy involved in mental rotation tasks by examining 2 types of spontaneous gestures (hand-object interaction gestures, representing the agentive hand action on an object, vs. object-movement gestures, representing the movement of an object by itself) and different types of verbal descriptions of rotation. Hand-object interaction gestures were produced earlier than object-movement gestures, the rate of both types of gestures decreased, and gestures became more distant from the stimulus object over trials (Experiments 1 and 3). Furthermore, in the first few trials, object-movement gestures increased, whereas hand-object interaction gestures decreased, and this change of motor strategies was also reflected in the type of verbal description of rotation in the concurrent speech (Experiment 2). This change of motor strategies was hampered when gestures were prohibited (Experiment 4). The authors concluded that the motor strategy becomes less dependent on agentive action on the object, and also becomes internalized over the course of the experiment, and that gesture facilitates the former process. When solving a problem regarding the physical world, adults go through developmental processes similar to internalization and symbolic distancing in young children, albeit within a much shorter time span..