How do voters of the other three parties fare? First, we should consider the propensity amongst the voters of the Greens and UKIP for relative centrism on economic matters, such as redistribution, but radicalism on social issues, such as immigration. Liberal Democrat voters in 2015 were highly centrist on economic issues and centre-left on social issues.[1] Given this, the associations between party choice and conscientiousness and open-mindedness come as little surprise, except perhaps in the strength of their effect.
UKIP and Green voters are the most closed and open-minded respectively, suggesting that attitudes to immigration are particularly affected by this trait. Green voters are far less conscientious of social norms than any other party, with UKIP voters around the national average. Liberal Democrat voters rank in the middle of all five parties on both traits. On emotional instability, UKIP voters are more neurotic than we might expect and Green voters scores especially highly on this trait. Finally, on agreeableness and extroversion, the two traits with the least evidence of association with party choice in the literature, we see interesting results. Green, Liberal Democrat and UKIP voters are all less agreeable and less extrovert than the voters of the major two parties. Disagreeableness and introversion may therefore be key personality traits of the protest voter.
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[1] Z-scores on (1) redistribution: Labour: 0.42, Green: 0.36, Liberal Democrat: 0.02, UKIP: -0.06, Conservatives: -0.61 (2) immigration: Green: 0.61, Liberal Democrat: 0.34, Labour: 0.19, Conservatives: -0.26, UKIP: -0.82