Uncommon Knowledge

What raises murder rates

Surprising insights from the social sciences

By Kevin Lewis
February 28, 2010

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A recent analysis of global homicide rates came up with some interesting conclusions. It turns out that the proportion of young males, population density, degree of urbanization, and income inequality are not significant predictors of the homicide rate. Instead, ethnic and linguistic diversity, education, and the quality of governing institutions were the most significant factors. Although it’s not surprising that ethnic strife and law enforcement matter for the homicide rate, there was a surprising effect found for education: An extra year of school for the average female increased the homicide rate almost as much as one less year of school for the average male.

Cole, J. & Marroquín Gramajo, A., “Homicide Rates in a Cross-Section of Countries: Evidence and Interpretations,” Population and Development Review (December 2009).

What executives’ voices give away
A good interrogator can often detect dishonesty by paying close attention to the way someone talks. A new analysis of corporate earnings conference calls suggests that Wall Street might benefit from these same skills. Using sophisticated voice analysis software, researchers found that the emotions of the executives who were grilled by stock analysts on these calls were predictive of future company performance. When executives were positive, positive future news releases and earnings surprises were more likely, and likewise for negative emotions and negative performance. Nevertheless, although these emotions did induce a market reaction, the analysts themselves generally incorporated positive but not negative emotions into forecasts, so stock prices didn’t completely anticipate the bad news.

Mayew, W. & Venkatachalam, M., “The Power of Voice: Managerial Affective States and Future Firm Performance,” Duke University (November 2009).

It’s cheaper to say you’re sorry
Don’t offer me money, just say you’re sorry. That’s the conclusion of a customer-service experiment with a company selling goods on eBay. Customers who gave the company neutral or negative evaluations - a rare and public signal of disapproval - were randomly offered either an apology, a small amount of money, or a larger amount of money to rescind their evaluation. Even though the apology was nothing more than a self-serving corporate message, customers were twice as likely to rescind their evaluation if offered the apology than if offered money.

Abeler, J. et al., “The Power of Apology,” Economics Letters (forthcoming).

”A” is for achievement
In case you haven’t noticed, subliminal influences are everywhere. In some of the latest experiments, researchers found that incidental exposure to letters associated with grades (like “A” or “F”) can enhance or undercut subsequent performance on tests. When “Test Bank ID: A” or “Subject ID: A” was written in the corner of their test pages, students performed significantly better on analogy and anagram tests compared to tests with “F” instead of “A” written in the corner. Although none of the students expected this effect, it seems to have worked by increasing motivation - students with “A” tests generated more achievement-oriented words on a word-completion test.

Ciani, K. & Sheldon, K., “A versus F: The Effects of Implicit Letter Priming on Cognitive Performance,” British Journal of Educational Psychology (March 2010).

Handsome is as handsome drives
Sure, we all know the stereotype about guys driving fancy cars to impress the ladies. But is there a real effect, and does it also apply to men who see women driving fancy cars? Psychologists in Britain showed people photographs of an average-looking man or woman, each seated in either a Bentley Continental or a Ford Fiesta. Consistent with the stereotype, women thought the man looked more attractive in the fancier car. However, a fancy car didn’t make the woman more attractive to the men.

Dunn, M. & Searle, R., “Effect of Manipulated Prestige-Car Ownership on Both Sex Attractiveness Ratings,” British Journal of Psychology (February 2010).

Kevin Lewis is an Ideas columnist. He can be reached at