Messages intended to suppress votes can be precisely delivered to particularly vulnerable and consequential groups of people via social media and keep millions of them from casting ballots, according to a new study that is the first to quantify the effect of this kind of microtargeting on voter turnout. A team led by a researcher at the University of Wisconsin–Madison recruited more than 10,000 people across the United States—a group representative of the country's voting population—to install an app that captured every ad they viewed for the six weeks leading up to the November election in 2016.
