Monkeys Predict US Elections

Abstract

How people vote often defies rational explanation. Physical traits sometimes sway voters more than policies do-but why? Here we show that rhesus macaques, who have no knowledge about political candidates or their policies, implicitly predict the outcomes of U.S. gubernatorial and senatorial elections based solely on visual features. Given a pair of candidate photos, monkeys spent more time looking at the loser than the winner, and this gaze bias predicted not only binary election outcomes but also the candidates' vote share. Analysis of facial features revealed candidates with more masculine faces were more likely to win an election, and vote share was a linear function of jaw prominence. Our findings endorse the idea that voters spontaneously respond to evolutionarily conserved visual cues to physical prowess and that voting behavior is shaped, in part, by ancestral adaptations shared with nonhuman primates.

Keywords: Biological sciences - Neuroscience; Social sciences - Psychological and Cognitive Sciences; ecological rationality; election; facial masculinity; gaze; non-human primate.

Figure 1:

a: Example gaze patterns for gubernatorial elections in Oregon (2006, top) and Massachusetts (2002, bottom). Cross: central fixation spot. Filled circles: fixations on candidate pictures; circle sizes: fixation durations. Magenta: fixations on election winner; green: fixations on loser. b: Monkey gaze bias as a function of election outcome and candidate gender. c: Gaze bias restricted to male-male races. d: Average proportion of elections correctly predicted by gaze bias (n = 3 monkeys, 6 gubernatorial and 6 senatorial sessions in total). Error bars: mean ± SEM. e: Correlation of number of fixations on candidate with vote share. Error bars: 95% confidence interval.

Figure 2:

a: Facial feature measurements. b: Correlation of jaw prominence (jaw width/cheekbone width) with vote share. Line: linear regression. c: Correlations between all masculine facial features and vote share. d: Correlation of monkey gaze bias and vote share. Error bars: 95% confidence interval. e: The probability of the Democratic candidate winning versus losing in blue states, swing states, and red states. f: Monkey gaze bias for blue state, swing state, and red state elections. g: Gaze bias for Democratic and Republican presidential candidates as a function of election outcome. h: Gaze bias for elections between Donald Trump and his Democratic opponents over three successive elections. Error bars: mean ± SEM.