December 17, 2012

Brain Changes as Trust Rises With Age

An untrustworthy man in a senior’s doorway.

Older adults are more likely than younger ones to perceive dishonest faces as trustworthy, according to a new study of social judgments and brain activity. The findings may help explain why older people are more likely to fall victim to fraud.

Up to 80% of scam victims are over 65, according to the U.S. Federal Trade Commission (FTC). Some experts suspect that older people are more vulnerable to fraud because they are more trusting than younger adults. But it hadn't been clear whether the differences might have a biological basis.

A team led by Dr. Shelley Taylor at the University of California, Los Angeles, set out to explore whether older adults perceive facial cues related to trustworthiness differently from younger adults. The researchers showed photographs of faces selected to look trustworthy, neutral or untrustworthy to a group of 119 older adults (ages 55 to 84) and 24 younger adults (ages 20 to 42). Signs of untrustworthiness included averted eyes, insincere smiles and a backward tilt of the head. The participants were asked to rate each face based on how trustworthy or approachable it seemed.

A smaller group of participants performed the same task while the scientists used functional MRI to look at changes in brain activity. The study was funded by NIH’s National Institute on Aging (NIA) and appeared online on December 3, 2012, in the Proceedings of the National Academies of Sciences.

Neutral faces and faces high in trust cues were rated similarly by both groups. However, the older adults were significantly more likely than the younger ones to rate untrustworthy faces as trustworthy. “Most of the older adults showed this effect,” Taylor says. “They missed facial cues that are pretty easily distinguished.”

The functional MRI scans revealed significant differences in brain activity between the age groups. An area known as the anterior insula, which is associated with “gut feelings,” became more active in the younger subjects at the sight of an untrustworthy face. Older subjects, however, showed little to no activation in this area.

“The older adults do not have as strong an anterior insula early-warning signal; their brains are not saying ‘be wary,’ as the brains of the younger adults are,” Taylor says. Future research is needed to determine whether this is because older adults are paying less attention to important social signals or whether their brains are somehow unable to process those signals.

Misplaced trust can have severe consequences for older adults, especially when it comes to financial fraud. “Older adults seem to be particularly vulnerable to interpersonal solicitations, and their reduced sensitivity to cues related to trust may partially underlie this vulnerability,” Taylor says.

—by Meghan Mott, Ph.D.

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References: Proc Natl Acad Sci U S A. 2012 Dec 3. [Epub ahead of print]. PMID: 23213232.