Automatic behavioural responses to valence: Evidence that facial action is facilitated by evaluative processing

Are motor schemata of facial action spontaneously activated upon the processing of evaluative information? In this case, the processing of positive evaluative information should immediately trigger the motor schema of smiling, and the processing of negative information should trigger frowning. This hypothesis was tested in two experiments in which participants were required to respond to positive and negative words by either smiling or frowning. Electromyogram (EMG) activity was recorded over the brow muscle region (corrugator supercilii) and over the cheek muscle region (zygomaticus major) in order to quantify the latency of muscular response as a dependent measure. In Experiment 1 we found that participants were faster at contracting their zygomaticus muscle (which is involved in smiling) when evaluating positive words, and faster at contracting their corrugator muscle (which is involved in frowning) when evaluating negative words. In Experiment 2, participants were required to respond with the contraction of one of the two muscles whenever a word appeared on the computer screen. Again, we found that responses were faster to congruent response valence combinations than to incongruent response valence combinations. These findings support the hypothesis that evaluative processing is directly linked to motor schemata of facial muscles.