Fig. 1: Trial structure for the effort-discounting, and information-seeking tasks.

a In the effort-discounting task, participants chose between a fixed low-reward/low-effort baseline (left of screen), and a variable high-reward offer (right of screen) associated with an equal or higher level of effort. Effort was indicated as the height of a target line on a vertically-oriented force bar. Participants received real-time feedback of their force exertion, before the outcome of their choice was revealed. b In the information-seeking task, participants had to decide whether they were willing to invest effort to obtain advanced information regarding an unchangeable lottery outcome. Each lottery involved a set of nine red or black cards, and participants won the lotteries in which the majority of the cards belonged to a predesignated winning colour (here, black). In the ‘Scenario’ event, participants were presented a subset of cards, and were asked whether they were willing to invest effort to reveal the identity of the remaining cards. Higher effort levels were depicted further to the right of a horizontal force bar. They were told that their choices would not alter the final outcome of the lottery, which was predetermined. At the ‘Choice’ event, participants could either choose to reveal the remaining cards for that effort level (‘Y’), or remain ignorant about the remaining cards for minimum effort (‘N’). If participants chose to reveal the cards, they exerted their chosen level of effort (the ‘Effort’ event), and the hidden cards were revealed (the ‘Reveal’ event). If participants chose not to reveal the cards, they exerted minimal effort, and the same starting configuration of cards as in the ‘Scenario’ event was displayed. The final outcome of the lottery was presented at the end of the trial (‘Outcome’). Δt indicates jitters of 3–6 s.