From a Science Daily summary of the MIT research:
Throughout most of 2016, a significant percentage of the American public believed that the winner of the November 2016 presidential election would be a woman — Hillary Clinton.
Strikingly, a new study from cognitive scientists and linguists at MIT, the University of Potsdam, and the University of California at San Diego shows that despite those beliefs, people rarely used the pronoun “she” when referring to the next U.S. president before the election. Furthermore, when reading about the future president, encountering the pronoun “she” caused a significant stumble in their reading.
“There seemed to be a real bias against referring to the next president as ‘she.’ This was true even for people who most strongly expected and probably wanted the next president to be a female,” says Roger Levy, an MIT professor of brain and cognitive sciences and the senior author of the new study. “There’s a systematic underuse of ‘she’
pronouns for these kinds of contexts. It was quite eye-opening.”