Hands of confidence: When gestures increase confidence in spatial problem-solving

This study examined whether the metacognitive system monitors the potential positive effects of gestures on spatial thinking. Participants (N = 59, 31F, M = 21.67) performed a mental rotation task, consisting of 24 problems varying in difficulty, and they evaluated their confidence in their answers to problems in either gesture or control conditions. The results revealed that performance and confidence were higher in the gesture condition, in which the participants were asked to use their gestures during problem-solving, compared with the control condition, extending the literature by evidencing gestures' role in metacognition. Yet, the effect was only evident for females, who already performed worse than males, and when the problems were difficult. Encouraging gestures adversely affected performance and confidence in males. Such results suggest that gestures selectively influence cognition and metacognition and highlight the importance of task-related (i.e., difficulty) and individual-related variables (i.e., sex) in elucidating the links between gestures, confidence, and spatial thinking.