  We introduce an evolutionary game on hypergraphs in which decisions between a
risky alternative and a safe one are taken in social groups of different sizes.
The model naturally reproduces choice shifts, namely the differences between
the preference of individual decision makers and the consensual choice of a
group, that have been empirically observed in choice dilemmas. In particular, a
deviation from the Nash equilibrium towards the risky strategy occurs when the
dynamics takes place on heterogeneous hypergraphs. These results can explain
the emergence of irrational herding and radical behaviours in social groups.
