Why masks work
Wearing a mask increases the distance people keep to each other, a team from the Markets and Choice research area of the Economics of Change unit at WZB report in a recent Dicussion Paper. To study group behavior during the pandemic, they sent experimenters to stand in line in front of stores around Berlin - either with or without wearing a mask.
The idea was to see whether a mask was (falsely) interpreted as a sign of security and got people to stand closer - or warded them off instead. Trials were repeated before and after face masks were made compulsory in Berlin stores. The team found "no evidence that mandatory masking has a negative effect on distance keeping". Instead, masks increased distancing, with a stable effect for both periods.
The paper closes with an interesting implication for health policy: "Assuming that distancing is an effective measure against transmission of SARS-CoV2, we find no evidence that mandating masks has a negative spillover effect."