Researchers at University College London have developed a mathematical formula to assess happiness.
Their study sheds light on the neural processes that lead to happiness, which until now were assumed to depend on life's events but had never been traceable from moment to moment in a mathematical formula that takes into account expectations.
At the start of the study, 26 subjects were asked to make a decision in which their choices would lead to outcomes involving financial gain or loss.
During the task, their neural activity was measured using functional MRI to trace signals from the striatum, which are thought to depend on dopamine.
They were repeatedly asked how happy they were, and researchers compounded this data to build a computational model that weighs self-proclaimed happiness against recent rewards and expectations.
This model was later tested on 18,420 participants in a smartphone app called "The Great Brain Experiment," developed by UCL researchers.
Together with his team, lead author Dr. Robb Rutledge designed a game called "What makes me happy?" (accessible via the app) to put their formula to the test.
The equation worked, predicting participants' happiness, although awards were merely game points and financial gain or loss was not a possibility.
"We expected to see that recent rewards would affect moment-to-moment happiness but were surprised to find just how important expectations are in determining happiness," says Rutledge.
The study sheds new light on the relationship between happiness and expectations and indicates that it evolves from moment to moment, even during a simple smartphone app game.
"Life is full of expectations," says Rutledge. "It is often said that you will be happier if your expectations are lower. We find that there is some truth to this."
In fact, expectations may affect happiness before the outcome of an event, and Dr. Rutledge emphasizes that his formula takes into account the positive expectations of a much anticipated event.
"If you have plans to meet a friend at your favorite restaurant, those positive expectations may increase your happiness as soon as you make the plan," he says. "The new equation captures these different effects of expectations and allows happiness to be predicted based on the combined effects of many past events."
Researchers are hopeful that their formula will lead to a better understanding of mood disorders and to enhanced treatment methods.
The study was published in the journal Proceedings of the National Academy of Sciences.