Ronald Baily of Reason has gathered recent psychological research examining the personality characteristics of libertarians. He notes that Jonathan Haidt has had to revamp his left/right political ideology analysis to accommodate libertarians. They are different from the left and the right.
What did Haidt find?
“Libertarians share with liberals a distaste for the morality of Ingroup, Authority, and Purity characteristic of social conservatives, particularly those on the religious right.” . . . Libertarians put higher value on hedonism, self-direction, and stimulation than either liberals or conservatives, and they put less value than either on benevolence, conformity, security, and tradition. Like liberals, libertarians put less value on power, but like conservatives they have less esteem for universalism. Taking these results into account, Haidt concludes that “libertarians appear to live in a world where traditional moral concerns (e.g., respect for authority, personal sanctity) are not assigned much importance.”
Haidt and his colleagues eventually recognized that their Moral Foundations Questionnaire was blinkered by liberal academic bias, failing to include a sixth moral foundation, liberty. They developed a liberty scale to probe this moral dimension. Unsurprisingly, the researchers found that libertarians dramatically outscored liberals and conservatives when it came to putting a high value on both economic and lifestyle liberty. . .
[L]ibertarians scored lower than conservatives and liberals on agreeableness, conscientiousness, and extraversion. Low scores on agreeableness indicate a lack of compassion and a proud, competitive, and skeptical nature. Like conservatives, libertarians are not generally neurotic, tending to be emotionally hardy. And like liberals, libertarians scored high on openness to new experiences, indicating that they have broad interests. Libertarians scored lower than both liberals and (especially) conservatives on sensitivity to disgust. The authors suggest this tendency “could help explain why they disagree with conservatives on so many social issues, particularly those related to sexuality.