“The information voters acquire during a campaign can ‘activate’ — or make more salient — their preexisting values, beliefs, and opinions,” political scientists John Sides, Michael Tesler and Lynn Vavreck write in “Identity Crisis,” a vital new work on the political culture of the Trump era. “That is exactly how Trump won support: he activated long-standing sentiments” surrounding race, immigration and religion. In “The Forgotten,” journalist Ben Bradlee Jr. details how contempt for Washington, a perceived loss of dignity and fear of immigrants helped Trump win over white voters in a key Pennsylvania county. “Trump was able to activate, own, and even weaponize the resentments that Luzerne residents had,” Bradlee writes. And in “Cyberwar,” communications scholar Kathleen Hall Jamieson argues that Russian trolls’ efforts to “activate the Trump vote” were designed to increase animosity toward Latin American immigrants and Muslims as well as deepen worries about civil unrest.