How we solve some mental problems with our hands
The researchers recruited 86 American undergraduates, half of whom were prevented from moving their hands using Velcro gloves that attached to a board. The others were prevented from moving their feet, using Velcro straps attached to another board — but had their hands free.
From the other side of an opaque screen, an experimenter asked questions about gears in relation to each other. For example: “If five gears are arranged in a line, and you move the first gear clockwise, what will the final gear do?” The participants solved the problems aloud and were videotaped.
The videotapes were analyzed for the number of hand gestures the participants used (hand rotations or “ticking” movements, indicating counting); verbal explanations indicating the subject was visualizing those physical movements; or the use of more abstract mathematical rules, without reference to perceptual-motor processes.
The researchers then repeated the experiment and analysis with 111 British adults.
The researchers found that the people who were allowed to gesture usually did so, and they also commonly used perceptual-motor strategies in solving the puzzles. The people whose hands were restrained (as well as those who chose not to gesture even when allowed), used abstract, mathematical strategies much more often.
Their work will be published in an upcoming issue of Psychological Science, a journal of the Association for Psychological Science.