FIGURE 23.

Common currency coding of subjective value derived from different rewards in monkeys. A: behavioral choices between two juice rewards of varying amounts reveal common scale subjective economic value. Amounts at choice indifference (50% choice of either reward) reveal 3.2 times lower value of reward B than reward A (which serves as common scale reference). B: common currency coding of subjective value derived from different juice rewards in single orbitofrontal neuron. Response to reward-predicting stimulus increases with amount of either juice, irrespective of juice. This activity codes the decision variable of chosen value. [A and B from Padoa-Schioppa and Assad (405). Reprinted by permission from Nature Publishing Group.] C: rank ordered, ordinal behavioral preferences for different liquid and food rewards, as assessed in behavioral choices between blackcurrant juice (blue drop) and mashed mixture of banana, chocolate, and hazelnut food (yellow bananas). ∼, indifferent; <, preferred. D: common currency coding of subjective value in dopamine neurons (averages from 20 neurons). Colors refer to the rewards shown in C. [C and D from Lak et al. (301).]