The Science of Social Distancing

Origins

Since the beginning of the Covid-19 outbreak, many guidelines changed. Masks were initially advised against, and then for. Gloves were regarded as an essential accessory by many at first, and later even considered as causing more harm than gain by some experts. Stay at home orders changed to carefully go out. Besides washing our hands and practicing hygiene (always good advice), the only major guideline that survived these past months is social distancing. Seemingly, a simple enough request, but it is a lot more complex than it might seem.

According to WHO guides a distance of at least 1 meter (3 feet) is required between one person and the other. The logic goes that if you are too close, you can breathe in the droplets originated by an infected person coughing, sneezing, or speaking. These droplets might contain the Covid-19 virus.

The 3 feet rule was first recommended in the 1930s, based on a study done by William Wells from the Harvard School of Public Health. Wells researched tuberculosis and found that infected droplets tend to land within 3 feet of the place they originated in. Since then, the same findings were observed with the flu, SARS, and MERS. And so the 3-feet rule was brought back time and time again, with every similar disease breaking. Most recently, Covid-19.

A Matter of Personal Space

Social distancing is a matter of a person’s personal space. The man who founded the field in which personal space is studied is the American anthropologist, Edward Hall. Hall coined the phase Proxemics and his book “The Hidden Dimension” is considered a must-read for anyone interested in the effects caused by different spaces between humans. In his book, Hall categorized 4 distances:

Intimate distance — less than 1 inch to 1.5 feet(1 cm to 46 cm). Mainly reserved for lovers, family members, or close friends.

Personal distance — 1.5 feet to 4 feet (46 cm to 1.2 m). Meant to allow a friendly minimal contact.

Social distance — 4 feet to 12 feet (1.2 m to 3.7 m). Useful for an office setting or casual gatherings where no physical contact is wanted.

Public distance — 12 feet to 25 feet or more (3.7 m to 7.6m or more). Reserved for public figures in front of a large audience.

The intimate distance and the “close phased” personal distance are a sensitive issue for most people. If violated, one could feel anxiety, defensive, discomfort, arousal, or intimidation.

According to WHO social distancing guides, two people, not from the same household, are instructed to maintain what Hall called a “far phased” personal distance or a “close phase” social distance. In Hall’s book, he states that this distance keeps visibility clear, the other person’s features are easily seen with detail. Conversations could be held with a normal speaking voice. This seems like a perfect balance between guarding personal privacy and maintaining efficacity, while meanwhile keeping people medically safe.

A Matter of Shape

While distance is an important factor, the shape of one’s personal space is no less significant. Hall constructed his model by forming circles around the person (figure A). Other researches followed and formed different models. As Covid-19 spreads by droplets coming out of a person’s respiratory system and entering another’s respiratory system, it is clear that the highest risk for infection is face-to-face encounters. This might require Hayduk’s egg shape model (figure B), or Helbing and Molnar’s ellipse model (figure C). These models could keep the distance from our back and sides relatively short while adding more room in the front. In other words, these giants, social distancing crowns, given away by Burger King in Germany, might be better designed as an egg shape rather than a circle.

A Matter of Perception

One question that arises is how do we actually know to keep an accurate distance from each other? Studies have shown that people tend to keep a larger distance between people they dislike, but keep a shorter distance to people they feel connected to. Studies also showed that people tend to think desired and threatening objects are closer than neutral ones.

In a study where researchers showed participants different avatars, the virtual figures who were facing the participants were perceived 22 cm closer than the ones looking away. The authors also state that in shorter distances the participants had to take more time to estimate the length between them and the avatar. In longer distances, the estimation took less time.

The UK’s Behavioural Insights Team wanted to check how good are people at estimating 1 meter and 2 meters. It turns out people usually underestimate 2 meters and overestimate 1 meter. It seems like a 1-meter distance works in terms of perception, albeit estimating the correct distance might require a bit of time.

A Matter of Culture

A Swedish friend of mine told me a joke that is circling around the country. It goes that when authorities told the Swedes they will have to keep 2 meters (6 feet) apart, some citizens asked, “why so close”?

Personal space and social distancing are subjective and are affected by culture. Indeed, different countries decided on issuing different social distancing rules. China and France set a 1-meter rule. Germany, Italy, and Spain set 1.5-meters. The U.S set 3 feet (1.8 meters) rule. Whereas Canada, Israel, and the UK initially set a 2-meter rule (the UK has now switched to 1-meter-plus).

Personal space is perceived differently in different cultures. A huge study with almost 9,000 participants from 42 countries found that the distance usually kept in various social situations varies tremendously between countries.

Another study showed that citizens from countries that are more prone to individualism were more likely to go out and visit parks during the lockdown. people from countries with a higher rank in Hofstede’s un-certainty Avoidance Index — meaning they feel more uncomfortable with uncertainty — stayed more at home and avoided gatherings.

The political climate should also be taken into effect. It was shown, during the 2014–2015 Ebola outbreak in Liberia, that societies with lower trust in government were less likely to abide by social distancing rules. This although, the study found that these society members understood the risks and transmission pathways no less than others.

A Matter of Mental Health

Lastly, there is something else we should take into account. Social distancing will probably stay, in one form or the other, until a successful vaccine is manufactured and widely distributed. Mental implications are and will be, significant. Loneliness, depression, and stress could all be caused by a lack of human connection. This is even riskier to the older population, which is also at higher risk of severe symptoms of Covid-19. This is the reason behavioral scientists have recommended to change the term ‘social distancing’ to ‘physical distancing’. Doing so, they hope to highlight the fact that although physically apart, social connections are more important than ever.