If you ask someone to show you how to tie their shoe-laces or play Jenga, they will almost certainly use their hands to do so.
In a study investigating how gestures interact with thoughts, Beilock and Goldin-Meadow (2010) had participants trying to solve a test often used by psychologists called ‘The Tower of Hanoi’ task.
Essentially this involves moving some blocks from one tower onto another.
After completing this, participants were asked to explain how they had solved the puzzle to someone else.
Here’s the really interesting bit: people who had spontaneously gestured with only one hand when asked to explain their solution, took longer to solve the puzzle the second time.
In comparison, those who had spontaneously used both hands, though, were quicker–presumably because they immediately used both hands on the now-heavy block.
Source material from PsyBlog