Fig. 1: Experimental tasks.

During the cue period of the Ap-Av task (red dotted rectangle), red and yellow horizontal bars signaled, respectively, the offered amounts of reward and aversion on the monitor. The monkeys made a decision between acceptance and rejection of the combined offer and reported this by choosing either of two targets (cross for acceptance/approach; square for rejection/avoidance) that appeared during the response period. The locations of the peripheral targets were alternated randomly. During the Pavlovian trials within the Ap-Av task, single cues were presented immediately after the fixation period, and the monkey experienced the respective positive or negative outcomes. During Ap-Av-Ap-Ap sessions (purple dotted rectangle), the Ap-Av task (upper diagram) was presented in the first and third blocks, and the Ap-Ap task (lower diagram) was presented in the second and fourth blocks. During the Ap-Ap cue period, the red and yellow horizontal bars on the monitor signaled two different offered amounts of reward. The monkeys made a decision between the two alternative options and reported this by choosing either of two targets (cross for choosing the red bar; square for choosing the yellow bar) that appeared during the response period. The locations of the targets were once again alternated randomly. During the Ap-Ap Pavlovian trials, single cues were presented right after the fixation period, and the monkey experienced the respective positive outcomes indicated by the length of either cue. During the Ap-Av EMS task (green dotted rectangles), the Ap-Av task was presented in the first and third blocks, and the Ap-Av EMS task was presented in the second block. During the Ap-Av EMS block, EMS was delivered simultaneously with the cue onset for 1 or 1.5 s of the cue period. The red and yellow horizontal bars, respectively signaling the offered amounts of reward and aversion, appeared on the monitor. The monkeys made a decision between acceptance and rejection of the combined offer and reported this by choosing either of two targets (cross for acceptance/approach; square for rejection/avoidance) that appeared during the response period. The locations of the targets were alternated randomly. During the Pavlovian trials, EMS was delivered as for the choice trials.