It's a frequent scenario. Two young con artists walk a retired high school teacher to the bank and fleece him out of $17,000. But why did the man, in his 70s, fall for it?

It may be that older people are less able to identify shady characters than younger ones, according to a study by Shelley Taylor of the University of California, Los Angeles, published on Monday in the Proceedings of the National Academy of Sciences.

Adults older than 60 lost at least $2.9 billion in 2010 due to financial exploitation - ranging from home repair scams to complex financial swindles - up 12 percent from 2008, according to the MetLife Mature Market Institute.

To understand why, Taylor and colleagues did a series of studies comparing perceptions of trustworthiness among younger and older individuals. They found older people tended to miss common cues that suggest a person is not trustworthy.

"It's that 'uh-oh' response that people get," said Taylor, who directs UCLA's Social Neuroscience Laboratory. "The younger adults are getting that and the older adults are not."

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