Imagine this scenario: would you rather me giving $2 to you and $1000 to a politician or not giving you or the politician any money at all? Many people would choose the latter option, even though the first option gives them more monetary benefits.

People don’t always choose the option with more money because what people find rewarding is not simply the amount of money, but also social equity. When deciding which option is more rewarding, people consider both the amount of money and the inequity.

However, making decisions is different from learning from rewards. People always know which option feels more rewarding to them when making decisions, but learning from reward can happen very implicitly. People learn to choose the rewarding options without knowing it.

How can social inequity matter if people may not even realize that they learned from reward? We found that surprisingly, it matters! A lot! This suggests that social inequity profoundly impacts reward representation at all levels.

In 3 experiments (N=280), subjects tried to learn which of 3 keys gave more reward ($0, $1, or $2) in different contexts. The reward was split with another person. We manipulated the inequity level from 0% to 100%. The keypress only determined the total reward.

We found a huge inequity effect. When subjects received less than 50% of the reward, they learned more slowly and less effectively. Moreover, they were more sensitive to inequity levels under 50%. For example, 80% vs 90% made less difference to learning quality than 10% vs 20%.

We discovered that reinforcement learning is also socially contextual! We are currently working on an fMRI study to tackle follow-up questions about how the social brain ties to the learning brain, led by Mu-chen and in collaboration with Joe Kable. Stay tuned!

People don’t always choose the option with more money because what people find rewarding is not simply the amount of money, but also social equity. When deciding which option is more rewarding, people consider both the amount of money and the inequity.

Imagine this scenario: would you rather me giving $2 to you and $1000 to a politician or not giving you or the politician any money at all? Many people would choose the latter option, even though the first option gives them more monetary benefits.

Here is the full poster ;)