Intelligent people are more likely to trust others, while those who score lower on measures of intelligence are less likely to do so, says a new study. Oxford University researchers based their finding on an analysis of the General Social Survey, a nationally representative public opinion survey carried out in the United States every one to two years. The authors say one explanation could be that more intelligent individuals are better at judging character and so they tend to form relationships with people who are less likely to betray them. Another reason could be that smarter individuals are better at weighing up situations, recognizing when there is a strong incentive for the other person not to meet their side of the deal.

The study, published in the journal, PLOS ONE, supports previous research that analyzed data on trust and intelligence from European countries. The authors say the research is significant because social trust contributes to the success of important social institutions, such as welfare systems and financial markets. In addition, research shows that individuals who trust others report better health and greater happiness.

The Oxford researchers found, however, that the links between trust and health, and between trust and happiness, are not explained by intelligence. For example, individuals who trust others might have only reported better health and greater happiness because they were more intelligent. But this turns out not to be the case. The finding confirms that trust is a valuable resource for an individual, and is not simply a proxy for intelligence.

Lead author Noah Carl, from the Department of Sociology, said: 'Intelligence is shown to be linked with trusting others, even after taking into account factors like marital status, education and income. This finding supports what other researchers have argued, namely that being a good judge of character is a distinct part of human intelligence which evolved through natural selection. However, there are other possible interpretations of the evidence, and further research is needed to disentangle them.'

Researcher Professor Francesco Billari, also from the Department of Sociology, said: 'People who trust others seem to report better health and greater happiness. The study of social trust therefore has wider implications in public health, governmental policy and private charity, and there are good reasons to think that governments, religious groups and other civic organizations should try to cultivate more trust in society. Social trust has become an increasingly important topic for academics, who want to understand the causes of better health and greater happiness within society.'