The many debate faces of Donald Trump and Hillary Clinton

By THE DATA TEAM

LAST night was their final tussle. In their third presidential debate, Donald Trump and Hillary Clinton appeared on the same stage for the last time before the election on November 8th. True to form, it was a tawdry and bitter affair. Astute viewers will have noticed ample grimaces, smirks and shaking heads amid the candidates’ festival of traded insults and interruptions.

Using facial-analysis software developed by Microsoft, The Economist has sought to quantify Mr Trump and Mrs Clinton’s emotions during some of the most trenchant moments of the debates. For each frame of a supplied video clip, the program scans each face, identifies the positioning of its features, and applies relationships from academic psychology literature to measure the displayed level of several emotions, such as sadness, surprise, anger and contempt. Perhaps unsurprisingly, the data show Mr Trump’s usual expression to be something of a scowl. In contrast, Mrs Clinton prefers to affix a permanent smile, however insincere. American comedians have already noticed; their caricatures of the candidates often feature a remarkably pouty Mr Trump facing off against an overly grinning Mrs Clinton.

September 26th: First debate

It was the debate jab that her campaign had been preparing for weeks. After denouncing the Republican nominee as “a man who has called women pigs, slobs and dogs”, Mrs Clinton threw back at Mr Trump derogatory comments he had made about a former beauty queen, Alicia Machado. He appears displeased, barking out “Where did you find this?”, but not denying the charge. The facial-analysis software registers a clear moment of contempt on the Republican nominee’s face.

October 9th: Second debate

The candidates debated for the second time just two days after the publication of a Washington Post article showing a video of Mr Trump, recorded in 2005, talking in crude terms about women and bragging about his ability to grab women by the genitals without asking. Mrs Clinton presses the attack, also rebuking him for his continued castigation of Ms Machado. All throughout, our program diagnoses Mr Trump’s face with a blend of sadness and anger. The normally steady Mrs Clinton reveals a rare spike of contempt when she starts expanding her criticism of her opponent beyond his treatment of women.

October 19th: Third debate

After Mrs Clinton faced a tough question about a leaked transcript in which she said her “dream” was “a hemispheric common market with open trade and open borders”, the Democratic nominee quickly pivoted to Russia, which the American government alleges is attempting to interfere in the presidential election. Mr Trump takes the bait, and Mrs Clinton lands a solid blow by saying that Vladimir Putin only prefers her opponent because he would “rather have a puppet as president”. After some attempted retorts, her Republican rival shows a flash of anger while taking a sip of water. He then slumps back into his customary, saddened pout while Mrs Clinton finishes twisting the knife.

Despite its apparent precision, automated emotion capturing is far from perfect, cautions Mark Frank, a communications professor. It is unlikely to filter out personal tics, such as Mr Trump’s much-mocked lip pursing. Nonetheless, it will surely improve as algorithms become cleverer. Politicians will always be prone to fibs and worse, but this technology may eventually help voters to detect what candidates hope to obscure.