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    uncommon knowledge

    I’m a man! I know man stuff!

    Surprising insights from the social sciences

    EMILY THEIS FOR THE BOSTON GLOBE

    Not only do people hold stereotypes about what kinds of people hold which kinds of knowledge, but people even hold stereotypes about their own knowledge—or at least what they should be seen knowing. A study being published in a top economics journal shows that men and women have more or less confidence in the kinds of information they hold based on gender. In a group trivia experiment, even when men and women had individually demonstrated the same level of knowledge on a particular topic, men had less confidence in their answers for stereotypically feminine topics (such as literature or pop culture), while women had less confidence in their answers for stereotypically masculine topics (such as geography or sports). And informing people of their actual competency didn’t seem to improve their confidence in opposite-gender topics.

    Coffman, K., “Evidence on Self-Stereotyping and the Contribution of Ideas,” Quarterly Journal of Economics (forthcoming).

    Why people look different

    If you look at the faces of a bunch of sheep, say, it can be fairly hard to tell them apart, compared to the more varied faces of a bunch of people. Is this just an anthropocentric view? Not entirely, according to a new study, which proposes that humans evolved greater facial variety, compared to other species, to facilitate individual identity. Our facial features exhibit more variation than our nonfacial features: “For example, the breadth and length of hands are correlated...though the breadth and length of noses are not.” And there’s more variety in the genes that influence our facial features than for other genes—a pattern that appears to date back even to Neanderthals.

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    Sheehan, M. & Nachman, M., “Morphological and Population Genomic Evidence that Human Faces Have Evolved to Signal Individual Identity,” Nature Communications (forthcoming).

    Emotional, or educational?

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    Note to professors: If you want to boost course ratings, fill your class with emotion, no matter what kind. In several experiments, researchers found that people who wrote about an emotional experience right before or after reading a passage on an informational topic subsequently felt that they had learned more about that topic, even though they did no better on tests of actual knowledge. This effect on perceived learning was the same regardless of which emotion was evoked.

    Baumeister, R. et al., “Illusions of Learning: Irrelevant Emotions Inflate Judgments of Learning,” Journal of Behavioral Decision Making (forthcoming).

    The danger of bling

    There’s something of a New England tradition of millionaires wearing old shoes and driving modest cars just like regular folks. Maybe those people are onto something. States that experienced a higher level of inequality in conspicuous consumption (e.g., clothing, cars) across households also experienced more violent crimes, even controlling for demographics, education, unemployment, poverty, and police budgets. There was no association with property crime and no association between violent crime and inequality in total household spending, suggesting that violence is only affected by visible lifestyle differences.

    Hicks, D. & Hicks, J., “Jealous of the Joneses: Conspicuous Consumption, Inequality, and Crime,” Oxford Economic Papers (October 2014).

    Kevin Lewis is an Ideas columnist.
    He can be reached at kevin.lewis.ideas@gmail.com.