Accumulation of virtual tokens towards a jackpot reward enhances performance and value encoding in dorsal anterior cingulate cortex

Normatively, our decisions ought to be made relative to our total wealth, but in practice, we make our decisions relative to variable, decision-time-specific set points. This predilection introduces a major behavior bias that is known as reference-point dependence in Prospect Theory, and that has close links to mental accounting. Here we examined neural activity in the dorsal anterior cingulate cortex (dACC) of macaques performing a token-based risky choice task, in which the acquisition of 6 tokens (accumulated over several trials) resulted in a jackpot reward. We find that subjects make faster and more accurate choices as the jackpot reward becomes more likely to be achieved, suboptimal behavior that can readily be explained by reference dependence. This biased behavior systematically covaries with the neural encoding of corresponding offer values. Moreover, we found significant enhancement in speed, accuracy and neural encoding strength for easier levels of difficulty in detecting the offer with the best expected value. These results suggest a neural basis of reference dependence biases in shaping decision-making behavior and highlight the critical role of value representations in dACC in driving those biases.