Facial expressions in the time of a pandemic

Ever since I returned to in-person school in the fall, I had quickly noticed the diverse expressions people were able to convey through their eyes and nearby facial muscles. The most prevalent appeared to be the wink (or a half-wink); a wink would help convey emotions of confusion, accentuate the word “little” and its synonyms and total confusion.

Regardless of who I am conversing with, whether a friend or teacher, they would all employ the highly popular wink. Not only that, I have seen an increase in the use of eyebrows. Eyebrows are highly useful in storytelling and general conversations because they can be bent to express disgust, shock, sadness, and horror.  

I wondered if what I had noticed was studied officially, and it turns out that Nature had published a facial EMG survey that discusses the topic to an extent last year. EMG, or electromyography, measures muscle response or electrical activity in response to a nerve’s stimulation of the muscle. The test, which consists of one or more small electrodes inserted through the skin into the muscle, is used to help detect neuromuscular abnormalities.

The effects of face mask-wearing on facial expression were investigated in the Nature study by measuring the surface electromyography from zygomaticus major (or the muscles related to the mouth), orbicularis oculi and depressor anguli oris muscles when people smiled and talked with or without a mask, according to Nature. Because only the actions of the orbicularis oculi are facilitated by wearing the mask, it was concluded that mask-wearing may increase the recruitment of the eyes during smiling. 

Because a mask hides the mouth, interfering with the recognition of the wearer’s emotion and impression, the hypothesis that only a limited amount of emotion can be conveyed as a result, is arguable and highly probable, according to Nature.  

The study used the hypothesis that wearing a mask will enhance eye muscle involvement in smiling as the mask wearer attempts to communicate their smile to others. In order to investigate the effect of wearing a mask on facial expression, a sequence of tasks with facial EMG recording of orbicularis oculi, zygomaticus major and depressor anguli oris were used.  

Twenty female participants were asked to perform four behavioral tasks. In the “photo” task, the participants watched a movie in which an experimenter appeared and pretended to take a picture of the participant, who was asked to smile. The second was the “smiling” task, where participants were asked to make their biggest smile immediately after they heard a beep. The third was the “reading” task, where the participants read aloud the displayed 4 ATR 503 phonetically balanced sentences (or sentences containing phonetic events according to their frequency of occurrence in natural speech). The fourth task was the “talking” task. The participants talked about 2 themes (“What I’m addicted to these days” and “What I have enjoyed recently”) for up to 30 seconds.

 Figure 1

Schematic representation of the experimental design. (Photo courtesy of Lauren Lee)

All tasks were implemented with or without a surgical mask on the face (Fig. 1). Detailed procedures of the behavioral tasks and timing of wearing and taking off the mask were given by the in-house developed Python 3.7.3. To acquire the EMG from the orbicularis oculi and zygomaticus major muscles on the left, and from the depressor anguli oris muscle on the right, three active bipolar Ag electrodes were attached to the face. 

Figure 2 

The photo task average EMG signals recorded on the 3 muscles (orbicularis oculi, zygomaticus major, and depressor anguli oris) can be seen in Fig. 2. (Photo courtesy of Lauren Lee)

Figure 3

The smiling task group average EMG signals can be seen in Fig. 3. (Photo courtesy of Lauren Lee)

Figure 4

The reading task average EMG signals can be seen in Fig. 4. (Photo courtesy of Lauren Lee)

Figure 5 

The talking task average EMG signals can be seen in Fig. 5. (Photo courtesy of Lauren Lee)

The hypothesis was added upon; due to mask-wearing blocking the transmission of emotional information from the lower face, it was hypothesized that wearing a face mask “induces a compensatory increase in the action of muscles around the eye that indicate the individual is smiling.” 

The eye involvement in smiling was greater during mask-wearing compared to no mask (Fig. 2). To specify, there was sometimes an adaptation in the eyes that would indicate a smile, but there was no change in the behavior of the muscles in creating a smile with the mouth.

In short, eye involvement during smiling can be enhanced when people communicate their smile while wearing a face mask compared to without a mask, which supports my observations to an extent.