Abstract
The activation of the motor system during the passive observation of another individual’s motor behavior, a process termed motor resonance, is a fundamental neural mechanism underlying action understanding and social cognition. However, it is presently unclear to what degree this activation requires cognitive effort, or whether its automatic production instead requires effort to inhibit. To investigate these questions, we imposed cognitive load in the form of the n-back task onto a socially guided motor task, wherein participants were required to align their actions with those of an observed individual. Using electroencephalography (EEG) to measure suppression of oscillatory activity in the mu frequency band over sensorimotor areas, as our index of motor cortex activity, we found that the addition of cognitive load yielded diminished motor resonance, but only when participants were required to perform actions complementary to those being observed. These results provide preliminary support for the hypothesis that the production of motor resonance requires cognitive effort, but also raise further questions, regarding to what circumstances this effect might be constrained.