Timing and voluntary suppression of facial mimicry to smiling faces in a Go/NoGo task--an EMG study.

Results obtained with a novel emotional Go/NoGo task allowing the investigation of facial mimicry (FM) during the production and inhibition of voluntary smiles are discussed. Healthy participants were asked to smile rapidly to happy faces and maintain a neutral expression to neutral faces, or the reverse. Replicating and extending previous results, happy faces induced FM, as shown by stronger and faster zygomatic activation to happy than neutral faces in Go trials, and a greater number of false alarms to happy faces in NoGo trials. Facial mimicry effects remained present during participants' active inhibition of facial movement. Latencies of FM were short with 126-250 ms in Go trials, and 251-375 ms in NoGo trials. The utility of the Go/NoGo task, which allows the assessment of response inhibition in the domain of facial expression by installing strong prepotent motor responses via short stimulus presentation times and a great number of Go trials, is discussed.