Optimists are boring

Even if you haven’t read Anna Karenina, you will be familiar with Leo Tolstoy’s quote that “all happy families are alike, each unhappy family is unhappy in its own way.” Seems like Tolstoy was way ahead of his time, given recent findings in neuroscience.

A Japanese research team recruited a total of 87 volunteers for two brain scanning experiments. In each of the experiments, the volunteers were put into an fMRI scanner and randomly shown 20 descriptions of positive life events (e.g. “You will take an epic trip around the world.”), 20 neutral statements (e.g. “You will submit a document.”), 20 negative statements (e.g. “You will be fired by your company.”), and 20 death-related statements (e.g. “You will be diagnosed with terminal cancer.”).

Afterwards, their brain activation patterns were recorded, and at the end of the scanner experiment, the participants were asked to fill out a questionnaire measuring their attitude towards life and their general optimism. In the second experiment, the only difference was that he death-related questions were omitted so as not to be overly dramatic (this is a Japanese experiment, after all).

The charts below summarise the findings but need some explanation. Chart A on the top left shows the correlation of brain activity between volunteers in the first experiment. Volunteers are sorted from least optimistic to most optimistic, and blue colours indicate higher correlation. As you can see, the correlation in brain activity between optimistic people is larger than between pessimistic and optimistic people or between pessimistic people.

Chart B on the top right reinforces that pattern. It shows the ‘distance’ in brain activity between two individuals in a two-dimensional grid. Blue dots are optimistic people, who are clustered closely together, while red dots are pessimistic people who are spread out all over the place.

Charts C and D show the same data for the second experiment (the one without death-related events). In this case, the similarities between optimists are even more pronounced.

Brain scan similarity between optimistic and pessimistic people

Source: Yanagisawa et al. (2025)

The results are quite obvious, really. Optimistic people think alike and show similar brain patterns (how boring), while pessimistic people are more ‘neurodivergent’, showing rather distinctive patterns that differ from person to person. Or to paraphrase Tolstoy: “All optimistic people are alike, all pessimistic people are pessimistic in their own way.”