How well do we do social distancing?

During the pandemic of coronavirus disease 2019 (COVID-19), many jurisdictions around the world introduced a "social distance" rule under which people are instructed to keep a certain distance from others. Generally, this rule is implemented simply by telling people how many metres or feet of separation should be kept, without giving them precise instructions as to how the specified distance can be measured. Consequently, the rule is effective only to the extent that people are able to gauge this distance through their space perception. To examine the effectiveness of the rule from this point of view, this study empirically investigated how much distance people would leave from another person when they relied on their perception of this distance. Participants (N = 153) were asked to stand exactly 1.5 m away from a researcher, and resultant interpersonal distances showed that while their mean was close to the correct 1.5 m distance, they exhibited large individual differences. These results suggest that a number of people would not stay sufficiently away from others even when they intend to do proper social distancing. Given this outcome, it is suggested that official health advice include measures that compensate for this tendency.