  Many biological, psychological and economic experiments have been designed
where an organism or individual must choose between two options that have the
same expected reward but differ in the variance of reward received. In this
way, designed empirical approaches have been developed for evaluating risk
preferences. Here, however, we show that if the experimental subject is
inferring the reward distribution (to optimize some process), they will never
agree in finite time that the expected rewards are equal. In turn, we argue
that this makes discussions of risk preferences, and indeed the motivations of
behaviour, not so simple or straightforward to interpret. We use this
particular experiment to highlight the serious need to consider the frame of
reference of the experimental subject in studies of behaviour.
