This is the updated equation to predict happiness, where t is the trial number, w0 is a constant term, other weights w capture the influence of different event types, 0 ? γ ? 1 is a forgetting factor that makes events in more recent trials more influential than those in earlier trials, CRj is the certain reward if chosen instead of a gamble on trial j, EVj is the average reward for the gamble if chosen on trial j, and RPEj is the RPE (reinforcement prediction error) on trial j contingent on choice of the gamble. The RPE is equal to the reward received minus the expectation in that trial EVj. If the CR was chosen, then EVj = 0 and RPEj = 0; if the gamble was chosen, then CRj = 0. The variables in the equation are quantities that the neuromodulator dopamine has been associated with in previous neuroscience studies. The additional term w4 relates to advantageous inequality (guilt) when the reward received by the subject Rj exceeds the reward received by the other player Oj, and w5 relates to disadvantageous inequality (envy) when Oj exceeds Rj.
CREDIT: Robb Rutledge, UCL
A new equation, showing how our happiness depends not only on what happens to us but also how this compares to other people, has been developed by UCL researchers funded by Wellcome.
The team developed an equation to predict happiness in 2014, highlighting the importance of expectations*, and the new updated equation also takes into account other people’s fortunes.
The study, published in Nature Communications, found that inequality reduced happiness on average. This was true whether people were doing better or worse than another person they had just met. The subjects played gambles to try to win money and saw whether another person won or lost the same gambles. On average, when someone won a gamble they were happier when their partner also won the same gamble compared to when their partner lost. This difference could be attributed to guilt. Similarly, when people lost a gamble they were happier when their partner also lost compared to when their partner won, a difference that could be attributed to envy.