The impact of facemasks on emotion recognition, trust attribution and re-identification

Abstract

Covid-19 pandemics has fostered a pervasive use of facemasks all around the world. While they help in preventing infection, there are concerns related to the possible impact of facemasks on social communication. The present study investigates how emotion recognition, trust attribution and re-identification of faces differ when faces are seen without mask, with a standard medical facemask, and with a transparent facemask restoring visual access to the mouth region. Our results show that, in contrast to standard medical facemasks, transparent masks significantly spare the capability to recognize emotional expressions. Moreover, transparent masks spare the capability to infer trustworthiness from faces with respect to standard medical facemasks which, in turn, dampen the perceived untrustworthiness of faces. Remarkably, while transparent masks (unlike standard masks) do not impair emotion recognition and trust attribution, they seemingly do impair the subsequent re-identification of the same, unmasked, face (like standard masks). Taken together, this evidence supports a dissociation between mechanisms sustaining emotion and identity processing. This study represents a pivotal step in the much-needed analysis of face reading when the lower portion of the face is occluded by a facemask.

Figure 1

Experimental paradigm. (A). Stimuli consisted of faces from the Karolinska Directed Emotional Faces database (KDEF) and from a subset of the Chicago Face Database (CFD) validated for Italian subjects, presented in unmasked fashion (NM, left panel), or masked with either transparent (TM, central panel) or standard (SM, right panel) medical facemasks. (B). In the first experimental session, participants were presented with KDEF and CFD stimuli shown in NM, TM or SM condition. After each presentation, they were required to indicate the posed emotion selecting between 4 options (Fear, Sadness, Happiness and Neutral) and, subsequently, to rate the perceived trustworthiness on a 6-point Likert scale. (C). In the second experimental session, participants were presented with pictures of unmasked faces from the CDF database. One third (4/12) of the presented stimuli was also presented in the first session in one of the three Conditions (SM, TM, NM). For each picture, participants were required to judge whether they have seen the face or not.

Figure 2

Emotion recognition task. (A). Violin plots depicting the accuracy of the emotion recognition task, regardless of the posed emotion. Results show a significant main effect of Condition (TM, SM, NM). Emotion recognition in SM was significantly worse than both NM and TM, while no difference was found between NM and TM. (B). The figure illustrates, for each emotion, the impact of the presence/type of mask. Significant effects were found for Happiness, Sadness and Fear, with a significant drop for SM with respect to both TM and NM. No effect was found for the Neutral faces. (C). The figure illustrates, for each condition, which emotions were more affected by the presence/type of mask. Results show a mild but significant main effect of Emotion in TM and a stronger effect in SM, but no effect in NM. See Table 1 for post-hoc results. Error bars indicate confidence intervals. Horizontal bars indicate significant results (*p < .01; ** p < .001). Abbreviations: N: neutral, H: happiness, S: sadness, F: fear.

Figure 3

Trust attribution task. (A). Results for trustworthy and untrustworthy CFD faces, showing a significantly lower score for untrustworthy faces. Stimuli rated as untrustworthy shows a significant effect of Condition. See Table 1 for post-hoc results. (B) A main effect of Emotion was observed in each of the three conditions (NM, TM, SM) of the KDEF stimuli, with Happiness obtaining the highest scores. See Table 1 for post-hoc results. All conventions as in Fig. 2.

Figure 4

Re-identification task. The analysis of the correct re-identification of unmasked faces previously observed in masked (TM, SM) or unmasked (NM) fashion show a significant effect of Condition, indicating that the presence/type of mask affects the subsequent re-identification of that face, presented in an unmasked fashion. Boxplots within each violin represent interquartile ranges (IQRs). Black horizontal lines indicate median and black points are outliers. All conventions as in Fig. 2.