The present disclosure relates to a method of determining whether a live human face is present for use as part of a facial recognition system and/or method, whereby a moving stimulus is generated. Human face movement in response to the generated stimulus is predicted using a model. The stimulus is presented to a face of a person. A movement of the face in response to the stimulus is tracked using a camera, and it is determined whether a live human face is present by comparing the movement of the face against the prediction.