Keep Your Chin Up When You Want to Believe in Future Rewards: The Effect of Facial Direction on Discount Factors

Studies have shown that a person's current body state can affect his thinking (embodied cognition). We tested how value judgments can be changed by this. The results of our experiment demonstrated that participants tended to discount a future reward less when looking up than when looking down. Moreover, we found that the β parameter, which represents the value of immediate rewards relative to delayed rewards received at another point in time, significantly differed between the two conditions; whereas the δ parameter, the discount rate in the standard exponential formula, did not show a significant difference. Using functional magnetic resonance imaging, McClure et al. (2004) showed that β is mediated by the lower level, automatic processes of the limbic structures; δ is mediated by the lateral prefrontal cortex, supporting higher cognitive functions. Combining the above two results, we can conclude that the embodied cognition in our experiment was mainly produced by the lower level brain processes. We believe that the knowing that discount factor β can be controlled by posture can be applied when designing robot behavior, such as encouraging a diet, trying to sell insurance, or offering customers a card loan.