Test subjects paired with mean robots were faster and made fewer mistakes than those paired with friendly ones or with no robot. Researchers at the University of Clermont Auvergne in France say a mean robot could motivate human employees to improve their cognitive performance, compared to supervision by a friendly robot or no robot supervision. The team employed the Stroop task, a test in which words printed in different colors are displayed on a screen, with test subjects required to identify the color while ignoring the word. Into this task Clermont Auvergne's Nicolas Spatola and colleagues presented a humanoid robot perceived either as friendly or mean. Participants paired with mean robots were faster and made fewer errors than those paired with friendly ones or with no robot at all.