For half the trials, the SS option was displayed on the left of the screen, and the LL option was displayed on the right of the screen, with these positions reversed for the other half of trials. Participants indicated their choices with left- and right-button presses via keyboard (Study 1) or button box (Study 2). In the Willpower task (Figure 1A), we measured the effortful inhibition of impulses to choose the SS. Participants did not make an explicit

choice during the initial phase but pressed a third key to enter the delay phase. Upon entering IOX1 supplier the delay phase, the SS reward became available for selection, remaining so for the duration of the delay. The LL reward was not available for selection until the end of the delay phase. Participants could terminate the delay phase at any time by selecting the SS, at which point they entered

the reward delivery phase, followed by the ITI. In order to select the LL reward, participants Trichostatin A solubility dmso had to resist the temptation to choose the available SS for the duration of the delay until the LL reward became available. In the Choice task (Figure 1B), participants initially made a simple choice between LL and SS during the decision phase. If SS was chosen, participants entered the reward delivery phase, followed by the ITI. If LL was chosen, participants entered the delay phase, followed by the reward delivery phase and the ITI. Critically, the SS was not available during the delay phase of the Choice task. Thus, contrasting neural activity during the delay phase of the Willpower task (in which the SS was available) with neural activity during the delay phase of the Choice task should yield brain regions associated with the effortful inhibition of impulses to choose the SS, controlling for LL reward anticipation (which is matched across conditions). In the Precommitment

task (Figure 1C), which was inspired by the animal literature (Rachlin and Green, 1972 and Ainslie, 1974), during the decision almost phase participants chose whether or not to make a binding choice for the LL (“commit”). If participants chose to commit, they entered a delay phase during which the SS was not available, followed by the reward delivery phase and the ITI. If participants chose not to commit, they entered a delay phase during which the SS was available for the duration of the delay, as in the Willpower task. Thus, by choosing to commit, participants restricted their access to the SS option during the delay period. In the Opt-Out task (Figure 1D), participants made an initial choice between LL and SS during the decision phase. If SS was chosen, participants entered the reward delivery phase, followed by the ITI. If LL was chosen, participants entered the delay phase during which the SS was available for the duration of the delay, as in the Willpower task.