Exploring cross-task compatibility in perceiving and producing facial expressions using electromyography.

Using a dual-task methodology we examined the interaction of perceiving and producing facial expressions. In one task, participants were asked to produce a smile or a frown (Task 2) in response to a tone stimulus. This auditory-facial task was embedded in a dual-task context, where the other task (Task 1) required a manual response to visual face stimuli (visual-manual task). These face stimuli showed facial expressions that were either compatible or incompatible to the to-be-produced facial expression. Both reaction times and error rates (measured by facial electromyography) revealed a robust stimulus-response compatibility effect across tasks, suggesting that perceived social actions automatically activate corresponding actions even if perceived and produced actions belong to different tasks. The dual-task nature of this compatibility effect further testifies that encoding of facial expressions is highly automatic.