Questionnaires
Questionnaires presented after the fMRI experiment assessed the perceived risk of options and difficulty of decisions using a rating scale ranging from 1 (no difficulty) to 9 (very difficult). Participants were further asked to rate how much they decided between options as a function of the amount of potential gain or potential loss of the choice and how much they felt influenced while choosing by the probability of wins and losses of their decision options. For all of these rating questions, we presented examples taken from the real experiment, which represented each of the experimental conditions respectively (one sample trial for each condition to remind participant of the condition). We realized all levels of risk and ambiguity; the ratings were made separately for each experimental trial that represented each condition.
We also included several personality questionnaires (results will be presented elsewhere) to assess trait-like differences related to decision-making (Budner, 1962; Carver & White, 1994; McLain, 2009; Zuckerman, 1996).