Deception and Lie Detection in the Courtroom: The Effect of Defendants Wearing Medical Face Masks.

During the COVID-19 pandemic, defendants and witnesses (as well as the prosecution and defense counsel) may wear medical face masks to prevent the spread of the virus. Alternatively, courtrooms proceedings may take place virtually. In this article, we discuss how these deviations from normal procedures may affect jurors' lie detection ability and decision-making. Although research addressing this specific question does not exist, we are able to formulate an informed view based on the extensive deception literature. Since nonverbal signs of deception in the face and body are virtually absent, we conclude that medical face mask-wearing or virtual courtroom proceedings will not hamper jurors' lie detection abilities. If jurors can hear the speech well, they may become better at detecting deception if they pay more attention to speech content, which may occur as a result of mask-wearing in the courtroom.

Surgical face masks impair human face matching performance for familiar and unfamiliar faces.

In response to the COVID-19 pandemic, many governments around the world now recommend, or require, that their citizens cover the lower half of their face in public. Consequently, many people now wear surgical face masks in public. We investigated whether surgical face masks affected the performance of human observers, and a state-of-the-art face recognition system, on tasks of perceptual face matching. Participants judged whether two simultaneously presented face photographs showed the same person or two different people. We superimposed images of surgical masks over the faces, creating three different mask conditions: control (no masks), mixed (one face wearing a mask), and masked (both faces wearing masks). We found that surgical face masks have a large detrimental effect on human face matching performance, and that the degree of impairment is the same regardless of whether one or both faces in each pair are masked. Surprisingly, this impairment is similar in size for both familiar and unfamiliar faces. When matching masked faces, human observers are biased to reject unfamiliar faces as "mismatches" and to accept familiar faces as "matches". Finally, the face recognition system showed very high classification accuracy for control and masked stimuli, even though it had not been trained to recognise masked faces. However, accuracy fell markedly when one face was masked and the other was not. Our findings demonstrate that surgical face masks impair the ability of humans, and naïve face recognition systems, to perform perceptual face matching tasks. Identification decisions for masked faces should be treated with caution.