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Experimental Psychology Seminar

Giulia Galli (Kingston University)

Brain potentials as an index of political choice

The standard approach to the measurement of political preferences ahead of an election consists of using surveys in which respondents are explicitly asked to express their views. However, predictions based on these surveys alone are not always accurate, as recent history suggests. In this seminar I will argue that political choice can reliably be predicted using event-related brain potentials. To do this, I will discuss two studies conducted during the 2016 EU referendum in the UK and the 2019 European Election in Italy. In both studies, before voting day participants were exposed to survey items while their brain activity was recorded with EEG. They then reported on their actual vote. The N400, a brain potential responding to semantic incongruencies and social disagreements, was predictive of future choice of voting “Remain” or “Leave” at the 2016 EU referendum and choice of voting populist or mainstream at the 2019 European Election. In decided and undecided voters the brainwave was a better predictor of future vote compared to explicit responses to the survey items during the experiment and to the Implicit Association Test scores, a gold standard for the measurement of implicit preferences. Using a classical component approach and multivariate pattern analysis, the European Election study further showed that the predictive validity of the N400 was mainly driven by survey items on economy issues. This is consistent with theories of economic voting, according to which voters’ behaviour is heavily influenced by the perceived state of the economy in their country. Altogether, the studies demonstrate that brain potentials can be predictive of future voting behaviour and may shed light into the determinants of voting choice.