| Summary: | <p>In this thesis, I investigated computational and neural mechanisms underlying
adaptive decision-making in social and non-social contexts. I focused on the
exploration/ exploitation dilemma, during which one has to choose
between exploiting the familiar option with relatively known value or exploring the
option with relatively uncertain value which might lead to a better outcome in the
future (reviewed in Chapter 1). Switching between exploration and exploitation
was dependent on external factors such as the number of future choice
opportunities (i.e. time horizon) and internal factors such as the belief estimates
about the accuracy of a predictor (‘accuracy’) and the subjective uncertainty in the
accuracy estimate (‘uncertainty’) (Chapter 2). I used functional magnetic
resonance imaging to investigate the neural correlates of accuracy, uncertainty and
their modulation during exploration and exploitation (Chapter 3). Medial and lateral
frontal areas were active during exploratory decisions, while ventromedial
prefrontal cortex had a unique role in representing multiple decision variables
depending on the current behavioural mode. Tracking one’s beliefs is not only
important when selecting between predictors, but also when evaluating one’s
confidence in the predictor. When we estimate our confidence we take into account
the identity of the predictor -- whether it is another social agent or a non-social
stimulus that provides information, as well as the experience that we have with the
agent or stimulus; people expressed more confidence for social compared to nonsocial
predictors. The difference between social and non-social confidence
judgments covaried with activity in right posterior temporoparietal junction
(Chapter 4). Not only are the estimates we form shaped by the social or non-social
identity of the predictors; in addition, whether we learn through direct experience of
another person’s actions or vicarious observation of such actions influences how
loyal or opportunistic we estimate these other people to be (Chapter 5).</p>
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