You would probably never sell out your friend for $5. But 500 cents? Now you’re talking!

Sure, the value is the same, but researchers have found that people are often lured into making decisions by numbers that seem bigger than they really are.

Writing in the January issue of Psychological Science, Ellen E. Furlong and John E. Opfer of Ohio State suggested that the flaw in thinking might lead people astray in activities as different as bargaining and gambling.

The researchers asked volunteers to take part in a behavioral test known as the prisoner’s dilemma, in which two partners are offered various rewards to either work together or defect.

The idea is that in the long term, the participants earn the most money by cooperating. But in any given round of play, they make the most if they decide to turn against their partner while he stays loyal. (The reward is lowest when both partners defect.)