How can you tell if someone's lying? The answer is, they're probably not.
Traditional economics says that people make reasonable choices and will lie if it's to their 1 . A recent university study has shown that, actually, we're pretty 2 —especially when we're at home.
Researchers in Germany 3 people at home and asked them to toss（投掷）a coin. There was a strong 4 incentive（刺激） to lie about the result: if the coin landed tails-up, the participants would receive money, while if the coin landed heads-up, they would get nothing. Because they were on the phone, they knew there was no5 of getting caught if they lied.
And yet people told the6 . Over hundreds of tosses, a coin will land tails-up about 50% of the time. In this 7 over half the people asked （55. 6%） said that the coin landed heads-up, which meant they would receive nothing.
Previous studies had found that people were more 8 . In those laboratory studies, 75% of people reported a 9 coin and asked for a reward. So the research team thinks it's being in our own homes which makes us play fair, although it's not yet clear why.
In fact both types of study show people are surprisingly 10 . Even in the laboratory, 25% of people 11 down a reward by telling the truth. The researchers say this is because honesty is 12 valued in human society. We care about our 13 and our sense of ourselves as decent (体面的) people. So lying has a psychological 14 and it seems this cost is more important than the financial benefits of 15 .
