People generally copy the visible behaviors of those around them, so there can be tipping points in both directions. As more and more people start to wear masks and obey rules of physical distancing, more people follow suit. Conversely, as more and more people ignore these practices, fewer people take them seriously. As psychologist Matthew Lieberman put it, “Our brains are built to ensure that we will come to hold the beliefs and values of those around us.”36
