Facial Recognition and Expression Detection in a Time of Mask-Wearing
By Elizabeth Kinard
In the unprecedented times of the coronavirus pandemic, there is much debate circulating about the numerous effects of the virus itself. However, there seems to be an extraneous factor— mask-wearing— which may prove detrimental in specific developmental ways. Though essential for decreasing the spread of the virus, one can imagine how the constant obstruction of over half of the face in social settings may inhibit facial recognition and expression deciphering abilities— especially among young children, in whom these abilities have not yet been solidified.
Facial recognition in humans is very advanced, and we have an incredible ability to distinguish between even the most similar of facial features. The process by which we can do this is accepted as a system containing multiple steps and involving many parts of the brain; it has been most directly correlated, however, to occipital and temporal lobe interactions. The occipital lobe, which enables visual processing, is activated by single features such as the eyes or nose and is mostly helpful for distinguishing between faces and objects, though both sets of information go to the temporal lobe for further processing. Once the visual information reaches the temporal lobe, it is part of the fusiform gyrus called the fusiform face area (FFA) that seems to be responsible for piecing individual facial features together and processing them as one entity. The FFA is responsible primarily for face recognition— not other body parts or objects (Lopatina et al., 2018; Norton, 2012). This mechanism has been supported by cases of prosopagnosia, which is associated with lesions in the occipitotemporal area and damage to the FFA, causing a severely inhibited ability to recognize faces (Barton et al., 2002).
Studies have also shown that the brain dedicates different neurons to individual feature perception, with a preference for internal features to recognize familiar faces and external features for unfamiliar faces. In this case, external features are the broad characteristics, such as head shape and size, within which the internal features, such as the nose or mouth, are located. For familiar faces, the most important internal feature for facial discrimination on average is the eyes (Aczél et al., 2016). However, given that the fusiform gyrus regulates facial recognition through holistic processing, external features such as head shape or hair color dominate over internal ones. In a study where the discrimination threshold was much lower for head and hair than for eyes, the results demonstrated a higher sensitivity to changes in external features. With this in mind, it is likely that facial recognition skills may be spared even while donning a mask, as the external features and eye area— both important aspects for facial discrimination— remain unobstructed (Logan et al., 2017).
However, it seems that this is not the case for the perception of facial expressions, a process which requires the activation of additional networks in the brain. In addition to the occipitotemporal network involved in facial recognition alone, the amygdala, which is the hub for emotional processing in the brain, is also implicated in the detection of facial expressions. Facial expressions provide emotional and reactionary information and are an essential means of nonverbal communication for small children who have not yet developed proficient language comprehension. In fact, children begin to mimic facial expressions very early on and hone their expression interpretation skills before they are even a year old, though it is said that they detect positive emotions far earlier than negative ones (Grossard et al., 2018). Regarding the role of specific facial features in emotional detection, it seems that the eye area— though previously identified as essential for facial recognition— is implicated more so in negative emotion detection, while the mouth area is more helpful for positive emotion detection. This is attributed to expressions of fear, anger, or surprise typically involving modulation of the eyes and brow ridge (i.e. frowning), while expressions of happiness primarily involve manipulation of the muscles around the mouth area (i.e. smiling) (Guarnera et al., 2015). With this, it is reasonable to say that masks obstruct one’s ability to detect positive emotions, with no significant impact on negative emotion detection. For small children, this could have a significant negative impact on social development, since they rely so heavily on facial expressions— particularly positive ones— for reassurance, social cues, and an establishment of self-efficacy. Furthermore, there is evidence that children with a decreased ability to decipher emotions have a harder time with social and academic adjustment in later stages of development, displaying increased learning difficulties and poor peer relationships, behavioral problems such as hyperactivity, or even elevated levels of anxiety (Goodfellow & Nowicki, 2009).
Therefore, it is clear that the ability to distinguish between emotions via facial expressions is very important to one’s social development and, when hindered, could potentially lead to social deficits among young people in the future. In learning and social settings for people of all ages and young children in particular, the inability to detect others’ emotions could prove to be very isolating, and negatively affect the development of social skills related to non-verbal cues such as facial expressions. Though it is unlikely that any of the proposed effects of mask-wearing on facial recognition and expression perception are yet observable, should the pandemic persist for a longer period of time, young children who attend in-person schools and are forced to learn and socialize behind masks could experience delayed development of these skills in the long run.
About the Author
Elizabeth Kinard is a junior at Harvard College concentrating in Neuroscience.
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