People lie less when they put on a medical face mask.

The current study examined how a face mask people wore during the COVID-19 pandemic affects frequent lying and successful telling and detecting lies and truths in a face-to-face deception task. Participants were psychology students who acted as senders and receivers of true and false communications under three conditions: visible face, wearing a face mask, and blindfolding in addition to the face mask. Participants arrived in groups of eight. They first completed a lying questionnaire and then participated in the deception task. Their goal was to outperform the rest of the group to retain a bonus of additional course credit. Results indicated that participants reduced the number of lies told when wearing the face mask compared to chance expectancy (d = -.27) and visible face (d = -0.21). In addition, participants were more successful in detecting truths in the face mask condition than in the visible face condition (d = 0.21). Finally, self-assessed lie-telling ability predicted frequent lying in the face mask but not in the other conditions. It was suggested that participants wearing the face mask were affected by the attitudes and norms that prevailed during the COVID-19 pandemic, where consideration was required, and people were relatively thoughtful and kind. The face mask reminded participants of these norms and motivated participants to act accordingly.