The layout of the state transitions followed that of a binary tree (see Figure 1a). The first state was always the same. Following the first left/right choice subjects transitioned into 1 of 2 different intermediate states with different state transition probabilities. Following the second left/right choice they transitioned into 1 of 3 different outcome states associated with different amount of monetary wins (0c, 10c, 25c) which were rescaled to 0, 0.4, and 1 for all behavioral modeling. The assignment of fractal images to states was randomized across subjects.
