Study: Clever people are more trustworthy!

In other words, they may be better at identifying when any particular person would be likely to act untrustworthily, based on the characteristics of the prospective interaction (e.g., material payoffs, discount rates).

'Alternatively, it may simply be that intelligent individuals have a greater chance of interacting with people who are materially better-off, and who therefore have less to gain from acting untrustworthily.

However, this seems quite implausible given that the relationship is robust to controlling for a great many different indicators of socio-economic position.'