Researchers supported by the Wellcome Trust have discovered how the brain assesses confidence in its decisions. The findings explain why some people have better insight into their choices than others.

Throughout life, we're constantly evaluating our options and making decisions based on the information we have available. How confident we are in those decisions has clear consequences. For example, a lack of confidence may make it harder to persuade others, or lead us to spend time re-evaluating previous decisions.

Researchers at the Wellcome Trust Centre for Neuroimaging at UCL led by Professor Ray Dolan have pinpointed the specific areas of the brain that interact to compute both the value of the options we have in front of us and our confidence in our decisions between those options.

The team used functional magnetic resonance imaging (fMRI) to measure activity in the brains of 20 hungry volunteers while they made choices between pairs of possible snacks to eat later. Then, to determine the subjective value of the snack options covered, the participants were asked how much they would be willing to pay for each individual snack. After each decision, they were asked how confident they were that they had made the right decision.

It has previously been shown that a region at the front of the brain, the ventromedial prefrontal cortex, is important for working out the subjective value of options. The new findings reveal that the level of activity in this area is also linked to how confident participants felt that they had chosen the best option. The study also found that some participants were better than others at reporting their level of confidence, and that this ability was associated with the interaction between the ventromedial prefrontal cortex and an adjacent area of the brain.

Dr Steve Fleming, a Sir Henry Wellcome Postdoctoral Fellow (now based at New York University), explains: "We found that people's confidence varied from decision to decision. While we knew where to look for signals of value computation, it was very interesting to also observe neural signals of confidence in the same brain region."

Dr Benedetto De Martino, a Sir Henry Wellcome Postdoctoral Fellow at UCL, added: "Overall, we think our results provide an initial account both of how people make choices, and also their insight into the decision process."

The findings are published online in the journal 'Nature Neuroscience'.