Abstract:

In situations in which individuals are motivated to conceal or repress their true emotions, their facial expressions may leak despite their efforts to conceal them. These leakages can be very useful for deception detection and many of these leakages are manifested in the form of micro-expressions. However, it is difficult for humans to accurately detect and recognize these micro-expressions. Studies have shown that facial feedback signals are effective cues in macro-expression recognition. Can facial feedback also be an effective signal in micro-expression recognition? In the present study, we investigated the effects of facial feedback on micro-expression recognition by conducting two behavioral experiments. In these two experiments, a restricting gel was applied to participants’ full face in order to enhance the facial feedback, whereas participants in the control condition had to apply the gel to their non-dominat inner arm. The pilot study showed that the gel manipulation can amplify facial feedback signals by perserving the initiation of muscual movements but increasing the resistance to these movements. In Exp 1, we investigated the effects of amplifying facial feedback on the recognition of intense micro-expressions. In this experiment, participants had to finish a micro-expression recognition task and a working memory task. In the micro-expression recognition task, micro-expressions (lasted for 50 ms, 150 ms, or 333ms) were sandwiched in between two 1s presentations of the same expresser’s neutral faces. In the working memory task, participants had to finish 16 modular arithmetic questions that have been shown to be highly sensitive to variations in working memory. In Exp 2, we investigated the effects of amplifying facial feedback on the recognition of subtle micro-expressions. The procedure of Experiment 2 was identical to the procedure of Exp 1, except that the facial stimulus of Exp 2 was very low in the intensity level of facial expressions. Results of the two micro-expression recognition tasks showed that, when the skin was made resistant to underlying muscle contractions via a restricting gel, the recognition accuracy of intense micro-expressions was unaffected, but the recognition accuracy was impaired for suble micro-expressions. The results of two working memory tasks showed that there were no significant differences in accuracy or reaction time between the facial feedback enhancement condition and the control condition, which excluded the possiblity that impairment in micro-expression recognition performance can be attributed to inadvertent effects of the facial feedback manipulation. These results indicate that facial feedback is a deleterious cue for micro-expression recognition. They also suggest that facial feedback mechanism needs a specific time window to be effective and dampening facial feedback may boost the micro-expression recognition accuracy.