Showing sympathetic figures with differing beliefs, discussed over a drink. Highlighting a shared identity. Correcting misperceptions about opposing partisans' views on democracy. Those are a few of the most effective strategies for reducing political polarization in the U.S., identified by a "megastudy" that surveyed more than 32,000 Democrats and Republicans to test 25 ideas crowdsourced from social scientists and other experts around the world.