Subjects were simultaneously presented with a left and right choice option, each comprising two cues (images). Once the cues were presented (Cue ON), subjects were free to saccade to the cues and choose their preferred option by moving the joystick toward it (Choice ON). The choice was confirmed by the highlighting of the selected option (Prefeedback), followed by reward delivery. The set of ten unique cues, each representing one of five reward magnitude or reward probability levels, was swapped every three to four recording sessions. Each stimulus set had ten new unique images, which represented the same set of five reward magnitude and reward probability levels (right).
