Why bribery works and what changes its effectiveness

The study indicates that when incentives are dependent on choices, people accept and reward bribes. On the other hand, when bribes are not contingent on delivering a certain outcome, they don't distort judgment nearly as much.

In the Carnegie Mellon experiment, pairs of participants wrote original jokes and submitted them to a judge, who was tasked with deciding which pun was the funniest. Joke-tellers could blindly submit bribes up to $5.

When judges were allowed to keep only one bribe, nearly 90 percent of them chose the joke that came with the most money. The better joke (as determined by independent evaluators) was selected just 60 percent of the time.

"Quality was basically ignored when the person could pocket the winner's bribe," said Silvia Saccardo, the Carnegie Mellon assistant professor of social and decision sciences who led the study. "Nearly every person went with the money."

The results were different when the judges could keep both bribes. They selected the better joke 84 percent of the time. In fact, they overwhelmingly chose the person who wrote the funnier joke even when they offered the lower bribe.

"When the referees' payoff didn't depend on the choice of winner, bribery didn't distort judgment," said Saccardo, a faculty member in CMU's Dietrich College of Humanities and Social Sciences. "And because they sided with quality instead of a higher payoff, it's an indication that in our data reciprocity isn't a driving factor when it comes to bribes."

The researchers, who also include scientists Uri Gneezy from the University of California San Diego and Roel van Veldhuizen from WZB Berlin Social Science Center, created one final scenario in the study that provided a clue that greediness can actually be overcome.

Rather than allowing participants to bribe the judge when they submitted their jokes, joke-tellers had to wait two minutes. The extra time allowed the judges to objectively read and evaluate the submissions before seeing any money. They could keep only the winner's money; they chose the better joke 81 percent of the time.

"When a bribe arrives before you have time to make an unbiased decision, you 'conveniently' convince yourself that a subpar proposal is actually the best one," Saccardo said. "It's more difficult to justify your own dishonesty once you've already made a decision before receiving a bribe."

The researchers replicated the main conditions of the study at a market in India using a taste-test. The results were consistent.

The World Bank estimates nearly $1 billion exchanges hands in bribes every year. By learning more about the ways our behavior and moral judgment can be affected through bribery, the researchers hope to identify ways to minimize its effect.

"Our results suggest that policy interventions that focus on increasing the moral costs of distortion and limit the scope for self-serving biases may provide a successful way to reduce the effectiveness of bribes," Saccardo said. "An example is requiring evaluators to follow objective evaluation criteria."