Many people believe they would be more satisfied if only they had more money. And events such as winning the lottery or receiving a large pay rise do make people delighted, at least momentarily.
But last works suggest that the main aspect driving happiness on such occasions is not the size of the reward received. Rather, it is how well that reward matches up with expectations.
Receiving a 20% pay rise when you were expecting 5% will make you feel happier than receiving 30% when you had been expecting 40%. This divergence between an expected and an actual prize is referred to as a reward prediction error.
Reward prediction errors have a main factor in learning. They motivate people to repeat behaviors that led to unexpectedly great rewards. But they also enable people to change their beliefs about the world, which is rewarding in itself.
Could it be that reward prediction errors are associated with happiness largely because they help us understand the world a little better than back?
To test this idea, University College London researchers Robb Rutledge and Bastien Blain created a task in which the likelihood of receiving a reward was extraneous to the size of the reward.
“Lot of people think they would be happier if they had extra money,” Dr. Rutledge said.
“However, we previously developed an equation for happiness showing that happiness depends not on how much reward you get, but whether you are doing better than expected.”
In the research, the researchers conducted two experiments with human volunteers, where they had to pick which car would win a race. If their chosen car won, they got a prize.
They knew what the potential prize was before they decided which car to bet on, but they could merely learn from experience which car was more likely to win the race.
In one case, one of the cars was consistently more likely to win, so the participants could learn after a several ‘races’ that they should pick that car to win, and boost their chance of winning. They should only bet on the slower car when the prize was really large.
The other case was more unstable, as which car was best would change up unexpectedly every so often.
The researchers established that prize size did not impact happiness; rather, participants were happier when they were able to learn which car was better, even when the reward size was low.
Being in an environment that changes a lot reduced their general happiness, especially among people with depressive signs.
“We found that happiness depends on learning, but unexpectedly, it doesn’t depend on reward,” Dr. Blain said.
“Whether study participants got small or large rewards didn’t matter for their happiness.”
Bastien Blain & Robb B. Rutledge. 2020. Momentary subjective well-being depends on learning and not reward. eLife 9: e57977; doi: 10.7554/eLife.57977