Multi-armed bandit task with 2 out of 4 cards each trial. On each trial, one out of two pairs of cards can be offered.
Key/location is irrelevant, only card identity. We added also shape trials in which no outcome is shown, and participants need to pick.
We manipulated between blocks two factors: Difficulty and Scarcity.
It means the reward function could be 0.25 and 0.35 or 0.65 and 0.75 for difficult blocks.
Or for easy blocks 0.1 and 0.5 and 0.5 and 0.9. Scarce blocks are the 0.25 and 0.35 and 0.1 and 0.5, and rich blocks are 0.65 and 0.75 and 0.5 and 0.9 blocks.