When someone installs rooftop solar panels, neighbors are increasingly
likely to do the same, especially if the panels are visible from the
street. It’s part of a phenomenon called behavioral contagion, which can
either have positive effects, as with solar panels, or negative
effects, as when people become more likely to drink excessively when
they spend more time with heavy drinkers. In “Under the Influence,”
economist Robert H. Frank talks about how peer influences alter the
policy choices we face under COVID-19 and climate change, and how we can
better harness the power of contagion for good.