In psychologist Hans Eysenck's P–E–N (psychoticism, extraversion and neuroticism) model of personality, psychoticism is a trait which is typified by aggressiveness and interpersonal hostility. In 2010, a paper titled "The nature of the relationship between personality traits and political attitudes" claimed to find a strong positive correlation between conservatism and psychoticism. This error was repeated in subsequent papers by the same authors; however, around 2015, the authors acknowledged the correlation is actually negative rather than positive, and began issuing corrections. The study instead indicates a strong positive correlation between liberalism and psychoticism.