Solving the exploration/exploitation trade-off is a fundamental issue for an organism living in an uncertain and changing environment. This review describes how a stream of cognitive neuroscience studies linked exploratory behaviour to structures in the human prefrontal cortex, then identified the brain mechanisms involved in the online adaptation of behaviour relatively to reward changes, and finally revealed fundamental limitations in the processing of information at the prefrontal level. The experiments and the results we present could particularly be of interest to economists who want to understand how cognitive neuroscience identify key processes in the human brain and shapes our understanding of decision-making.

In economics, three nested organizational levels, namely behavioural, mental and neural, can be distinguished. They introduce specific theoretical or observable concepts and suggest their own models for choice making. If psycho-economics relates implemented actions to declared mental states, neuro-economics relates mental states to brain areas. Bridge principles can be defined which link concepts with similar interpretations at two successive levels. Thanks to these principles, relations or even models independently suggested at two successive levels may well be associated. Some prescriptive applications of these principles were more recently proposed, but they remain grounded on a too fragile basis.

Recent developments of neuroimaging technology enable us to investigate the brain network implicated in economical decision making (Glimcher et al. 2004; Camerer 2008). One of the fascinating topic is “ambiguity aversion” where people tend to avoid unknown options as demonstrated by Ellsberg paradox. Although “ambiguity aversion” has been consistently observed in a variety of situations, uncertainty due to incomplete knowledge can be resolved by obtaining missing information, and people explore the ambiguous options as well.

Here, we review a number of neuroimaging studies on “ambiguity aversion” and associated works. It has been shown that the affective OFC and the cognitive prefrontal cortex play a crucial role in decision making under uncertainty. We discuss what kinds of cognitive function are involved in the decision making process by overviewing neuroimaing studies on higher cognitive processes in general including exploratory behavior.

In this article, we focus on two types of “aversion” which we deem essential aspects of the notion of trust: betrayal aversion (social) and ambiguity aversion (a special case of aversion to uncertainty). Based on trust-games studies in experimental economics and neuroeconomics, our main goal is to assess the conceptual, behavioral and neurobiological connections between betrayal and ambiguity aversions.

From a social and individual psychological point of view the bottom line of our trusting behavior could be our general aversion to ambiguous signals. We approach social trust in the terms of a phenomenon based on uncertainty aversion. Specifically, a reduction of the perceived uncertainty of a social interaction tends to build up a trusting climate conducive to trade by decreasing betrayal aversion. We hypothesize that betrayal aversion and ambiguity aversion bear such a negative correlation.

Focusing on this potential negative correlation our approach clearly differs from more positive accounts of trust centred on altruism.