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.

Cruel robot overlords get more out of their human subjects than nice ones. The mere presence of an unkind robot seems to improve our cognitive abilities, more than being watched by a friendly robot or even no robot at all. The effect of a robot observer on human performance was tested using the Stroop task, a test in which words printed in different colours appear on a screen, and test subjects must identify the colour, ignoring the word itself. We're usually worse at this – either taking longer to answer or making mistakes – when the colour and the word clash, like when the word "blue" is printed in green letters. To see how a robot would affect the test, Nicolas Spatola at the University of Clermont Auvergne in France and his colleagues added a small humanoid robot perceived either as friendly or mean into the experiment.