Kathleen Hall Jamieson of the Annenberg Public Policy Center said people can be primed to believe false information through repetition. “What Trump did was take tactics of deception and played to confirmation biases that were already circulating in our culture and embodied them in somebody who is president of the United States. He didn’t change what was available, but he changed its accessibility,” she said. “That crazed content has always been there. But it becomes dangerous when it is legitimized and when it has the power of the state behind it.”