Dr Sotaro Kita and his colleagues have published a study on how spontaneous gestures influence problem solving, in the September issue of Psychological Science. They found that when one spontaneously produces gestures during problem solving, one tends to solve the problem based on concrete spatial information as opposed to more abstract information.

Do gestures merely reflect problem-solving processes, or do they play a functional role in problem solving? We hypothesized that gestures highlight and structure perceptual-motor information, and thereby make such information more likely to be used in problem solving. Participants in two experiments solved problems requiring the prediction of gear movement, either with gesture allowed or with gesture prohibited. Such problems can be correctly solved using either a perceptual-motor strategy (simulation of gear movements) or an abstract strategy (the parity strategy). Participants in the gesture-allowed condition were more likely to use perceptual-motor strategies than were participants in the gesture-prohibited condition. Gesture promoted use of perceptual-motor strategies both for participants who talked aloud while solving the problems (Experiment 1) and for participants who solved the problems silently (Experiment 2). Thus, spontaneous gestures influence strategy choices in problem solving.

Alibali, M. W., Spencer, R. C., Knox, L., & Kita, S. (2011). Spontaneous Gestures Influence Strategy Choices in Problem Solving. Psychological Science, 22(9), 1138-1144
DOI: 10.1177/0956797611417722