Heart rate in the final presidential debate


With hearty.ai, we created an app to measure the heart rate of the two presidential candidates over the course of the final debate. Inferring heart rate from skin color changes on the forehead, we could track it over the course of the debate as a proxy for emotional intensity. This is an article about what kind of insights we can gain from looking at the debate with the candidates’ heart rates in mind.

Most factors influencing heart rate probably stay constant for the candidates during the debate, leaving emotional arousal or stress as the main source of variation. In other words, we can quantitatively distinguish tense, irritated, anxious phases from confident, unwavering, relaxed periods. We looked at the major topics of stress, the candidates’ strategy and the resulting outcome. Let’s get started!

The final presidential debate, in heart rates


Second Amendment

The debate starts with the classic argument about the right to carry firearms. The first bump is in Clinton’s heart rate where Trump says he is “very proud to have the endorsement of the NRA”. She obviously feels quite strongly about gun ownership. Despite that, her reaction is composed as she affirms her support of the Second Amendment and relativizes her previously critical standpoint on DC v. Heller. Interpretation: if you run for president, you’d better be able to represent your country’s stance, even if you personally disagree on a particular issue.

YouTube: 13:05


During the dispute on abortion, Clinton defends women’s right to choice and Planned Parenthood. Clinton visibly calms down in familiar territory, while Trump responds with his familiar fury – likely authentic, as reflected in his heart rate. Just watch his facial expressions.

YouTube: 14:45


One can clearly see Trump’s heart rate reacting to the accusations that he was bashing immigrants, and moreover, built Trump Tower using undocumented labor. On the topic of securing borders, there is a first glimpse into one of Clinton’s recurring strategies: with a wry smile, she dismisses a radical stance on a topic (here, the open borders) as ridiculous, getting some tension out of the debate. We can see how her physiology reacts to her smile, leading to a drop in her heart rate.

YouTube: 24:45

Wikileaks and US-Russia foreign relations

A side issue becomes a heated argument: Clinton turns the Wikileaks discussion from her wanting open borders to Russian espionage and influence on the presidential election. Her heart rate reaches one of the peaks of the debate as she argues for American autonomy. In a clear message, she is portraying herself as strong enough for leadership of the US. It is particularly amusing to watch how she turns Trump’s accusation of her “playing chicken” into a portrayal of her own leadership qualities.

YouTube: 29:30

Economy, NAFTA

Trump is talking about making NATO countries pay for military spending of the US, re-negotiation of NAFTA to avoid jobs fleeing “to Mexico and other places”, and lowering taxes. Clinton’s move in response, accompanied by her familiar dismissive smile together with a huge drop in her heart rate: “Let me translate that if I can, Chris”. She portrays herself as the level-headed, rational player as she explains how Trump’s plan would add $ 20 trillion to the national debt, while her plan would be “costed out” and would involve “investing into people”. She really moves with the times here.

YouTube: 40:18

Quantifying the interaction

We could go on with analyzing more debate moments here, but by now, we can see some familiar trends in the interaction. In general, we can see Clinton playing with a larger dynamic of her own heart rate. Her heart rate increase first as she is making a point. In response, Trump reacts with anger, denial or resentment, accompanied by a heart rate increase on his side, while Clinton herself relaxes, letting Trump’s emotional response speak for itself, or responds with her famous “fuck you smile“. However, there are a few exceptions where Clinton is reactive, and a notable one can be seen at 55:40.

We hope you enjoyed this analysis of the heart rate of the US presidential candidates during the debate. If you think we should provide heart rate during other televised events with large portrait shots, please let us know in the comments. If you are interested in tracking your heart health, sign up with your e-mail on hearty.ai and we will keep you updated about the beta launch of our mobile app.

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