The recent rise in controversial politicians has garnered substantial interest in the assessment of their personality. Observer ratings of politicians’ personality, however, may suffer from evaluative and value-related biases. Evaluative biases are likely to differentially affect personality ratings of preferred and non-preferred politicians, whereas value-related biases are likely to affect ratings of honesty-humility and openness to experience of preferred politicians in line with the self-based heuristic or assumed similarity effect. In a stratified sample (final N = 203) of the Dutch population, respondents/voters provided self-ratings and observer ratings of the political leaders of the seven largest political parties on the HEXACO Simplified Personality Inventory (HEXACO-SPI). Findings showed evaluative biases on honesty-humility, extraversion, conscientiousness, and openness to experience. Furthermore, observer ratings of politicians were generally lower than self-ratings on honesty-humility and higher on extraversion, suggesting high perceived politicians’ narcissism. Findings on the value-related bias showed that assumed similarity was higher for honesty-humility and openness to experience among politicians of a preferred party than among politicians of non-preferred parties. Additionally, assumed similarity effects were also present for emotionality among preferred politicians and for extraversion and conscientiousness among both preferred and non-preferred politicians, suggesting a self-based prototypicality effect.
- Assumed similarity
- Party leaders