Eight unique paired lottery menus were used (adapted from Holt & Laury10). For each menu, high and low payoffs for the safe and risky gambles were held constant, but the probabilities varied. (a) The high and low payoffs for each menu of gambles are shown here. To avoid potential biases for or against any particular menu, for each participant, gambles from four of the eight lottery menus were randomly selected to be presented, and trial order was randomized for menu x probability x trial type with a unique order per participant. (b) For scanning, we used the 6 pairs symmetric around the mean indifference point (for each menu, gambles 40%, 50%, 60%, 70%, 80% and 90% probability of high payoff).