The sources of trust: why we believe what we do

When we trust or distrust someone we believe certain things to be true about their likely future conduct. Where do we get these beliefs from?

I'm not talking in a neurological sense, though research using fMRI brain-scanning techniques has looked at how the brain processes judgements of trustworthiness. Apparently there are certain sections of the brain that become activated when we trust...

Nor am I going to go into research on hormone levels and trust. Apparently, oxytocin is a strong predictor of trustworthiness, while testosterone and cortisol are less so. All rather too biologically deterministic for my liking...

I'm interested in what evidence people use to base their judgements on, and where they source this evidence from. What is important about this is that the actual person being trusted (or not) might not have that great a direct input into the decision of the person weighing up whether to trust them (or not)...

Intuitively, we don't take our time to work out what we actually think about people's motives, competence, integrity and predictability when we trust them, or not... (Incidentally, Diego Gambetta at Oxford University has been doing some external forces. The most obvious example is the Hippocratic Oath signed by doctors, although even this cannot provide a cast-iron guarantee of a doctor's trustworthiness...

We trust, for example, accountants to audit firms' finances and assets accurately, for example. We don't know any of these accountants from the proverbial Adam, but we expect them to do their work with benevolence, competence and integrity because of professional codes of ethics (not that this stopped Arthur Andersen staff from facilitating the Enron scandal: you see how trust is only an expectation, not a guarantee?)