Ever since Trump’s implausible victory, experts have been scrambling to explain the ties that created his winning coalition. For all practical purposes, American presidential elections are binary – pitting one Republican nominee against a Democrat nominee. It sounds simple enough. Members of each party elect delegates that choose a candidate to represent them and a nominee is chosen, QED. But in 2016 things were upended by the impact of social media and the role of the amygdala. 
The past is not prelude.
In the past, the belief-sets that attracted an individual to a given party were relatively well-understood. Democrats tended to have progressive social views, be pro-individual, have modest incomes, and see a role for government in society. In contrast, Republicans tended to have a clear view of social norms, be pro-big-business, have greater income and wealth, and think a small government was the best.
Of course, those characteristics listed are imprecise and open to criticism, but the point is that it seemed feasible to reliably group people into one of two camps. It was an orderly era, and one which pollsters must have found blissful.
What resonated with Trump voters?
The era of easily recognized voting blocs appears to have been relegated to history with the Trump victory. Everyone is now trying to understand what positive, unifying chord Trump struck with his coalition that so effectively obliterated previous voter affiliations and so effectively confounded pollsters.
It would see there was no positive, unifying chord that motivated people to vote for Trump. Instead there was a negative chord of fear that resonated with millions of voters. Fear that Islam was intrinsically evil, fear of Mexicans flooding the border, fear of Obamacare, fear of ISIS, fear of immigrants, fear that America wasn’t great. Fear. Trump is an irrational pick for president, but when people vote their fears, they are by definition being irrational.
Year of the amygdala.
What Trump did to build his coalition was to effectively communicate a message of fear. To be sure, a message of fear needs no great policy paper to support it. It needs few facts. Trump was roundly criticized during the campaign for not having defined policies or even clear policy positions. In reality, he didn’t need them. What he was selling, and what his voters bought, was a message that precisely targeted the “fear center” of our brains – the amygdala.
Chris Mooney has written extensively about a possible connection between the big five personality traits (Openness, Conscientiousness, Extroversion, Agreeableness, and Neuroticism) and activity in the amygdala and the anterior cingulate cortex (ACC). In one article Mooney described the role of the ACC as “the error-detecting region that is thought to be involved in causing us to stop repeated patterns of behaviour and change course.”
If Mooney is correct about neurophysiological differences influencing political behavior, then clearly this election should be remembered as the year of the Amygdala. It is a year when people left previous beliefs behind, or were highly motivated to turn out and vote simply because the Trump message of fear was irresistible.
The social amplification of risk
No discussion of why Trump appealed to so many voters would be complete without at least mentioning the role played by social media. In 1988, Kaperson introduced the concept of social amplification of risk whereby the perceived risk of an event could be exacerbated by social activities and communication. If Trump is nothing else, he is a master of social media. What a powerful combination – to sell a message of fear and then intensive the fear of that message through social media.
On social media, facts are irrelevant to the message of fear. Speaking of facts, it was recently reported that “top fake election news stories generated more total engagement on Facebook than top election stories from 19 major news outlets combined.”
If this continues, we may someday find ourselves electing a person that’s never held political office, has no policy positions, but knows how to amplify messages of fear through social media.
It’s not just Trump.
It wouldn’t be at all unexpected to see Trump surround himself with amygdala-driven operatives. That is a discomforting thought – a room full of cabinet members or advisers, probably mostly white men, succumbing to the calls of their over-active amygdalas to react to events because they’re afraid.
Yes, there’s no doubt the world can be a scary place, but responding to frightful events is different than reacting to them. Trump will never change. Those of us who see the positive potential of America and the world must be vocal and visible in our optimism and must be ever vigilant to recognizing and responding to fear-based actions of a Trump administration.
 The Amygdala in 5 Minutes (YouTube video by neuroscientist, Joseph LeDoux)
 The Surprising Brain Differences Between Democrats and Republicans, http://www.motherjones.com/politics/2013/02/brain-difference-democrats-republicans
 Political divides begin in the brain
 Kasperson, R. E., Renn, O., Slovic, P., Brown, H. S., Emel, J., Goble, R., Kasperson, J. X. and Ratick, S. (1988), The Social Amplification of Risk: A Conceptual Framework. Risk Analysis, 8: 177–187. doi:10.1111/j.1539-6924.1988.tb01168.x