Leo Tolstoy’s epic novel Anna Karenina has among the most famous first lines of any book: “All happy families are alike; each unhappy family is unhappy in its own way.” Psychologists tend to agree. The evidence keeps piling up. Studies repeatedly find that people with desirable traits like good health, higher income, and subjective happiness are more similar to one another in personality, values, and other measures than people without these traits. This is known as the Anna Karenina principle.
Now a team of researchers in Japan has found this principle may leave an imprint in the very workings of the brain. Led by Kunio Yanagisawa from Kobe University, Japan, the team of researchers studied how the neural waves of optimists differed from those of pessimists, publishing their findings in PNAS Psychological and Cognitive Sciences.
Optimists are a well-studied bunch, with decades of experiments showing that, among other things, they tend to be more physically and mentally healthy, more successful romantically, earn higher incomes, and, crucially, tend to attract each other. Separate lines of research have also shown that highly optimistic people tend to have broader social networks, and that individuals who share a positive trait—such as high social position—tend to have similar personalities and similar neural patterns in their brains. The Japanese psychologists decided to explore the missing link between these observations.
The brain activation patterns were more similar among optimists, while the pessimists were all over the place.
For their experiment, they recruited a total of 87 participants spread across the optimism-pessimism spectrum, from people who were absolutely convinced that “good things come to those who wait” to folks who would rather not think about the future at all. All participants were healthy, married, and aged 25 to 44. The researchers tasked the participants with imagining a series of hypothetical future situations, like “you will take an epic trip around the world” and “your partner will win big at a horse race.” While they imagined these futures, the researchers recorded their brain activity with an fMRI machine.
A detailed statistical analysis of that data revealed something unexpected: The brains of optimists showed much sharper neural distinctions between positive and negative scenarios than the brains of the pessimists. The researchers determined that this was, in fact, consistent with research suggesting that optimists tend to visualize positive future scenarios more vividly and negative ones more abstractly. But there was another clear pattern in the numbers, one that confirmed Yanagisawa’s hypothesis: The brain activation patterns were indeed more similar among optimists, while those of the pessimists were all over the place, each its own idiosyncratic snowflake. This effect was especially strong in the medial prefrontal cortex, an area of the brain with important roles in memory and decision-making.
The results shed light on how different degrees of optimism vary at the neural level, and suggest that Tolstoy’s astute observation is not simply a matter of culture and environment, but also operates in the very electrical firings of the brain.
The great Russian novelist himself wrote Anna Karenina during one of the bleakest periods of his life. But the tragic novel ends with a line that suggests life is as good as we make it: “My whole life … has the unquestionable meaning of the good which it is in my power to put into it!” That sounds like unqualified optimism. 
Lead image: Azurhino / Shutterstock
