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In a brain-imaging study I conducted with Ray Dolan and Benedetto De Martino in 2009, we asked subjects to imagine going on vacation to 80 different destinations and rate how happy they thought they would be in each place. We then asked them to select one destination from two choices that they had rated exactly the same. Would you choose Paris over Brazil? Finally, we asked them to imagine and rate all the destinations again. Seconds after picking between two destinations, people rated their selected destination higher than before and rated the discarded choice lower than before.
The brain-imaging data revealed that these changes were happening in the caudate nucleus, a cluster of nerve cells that is part of the striatum. The caudate has been shown to process rewards and signal their expectation. If we believe we are about to be given a paycheck or eat a scrumptious chocolate cake, the caudate acts as an announcer broadcasting to other parts of the brain, "Be ready for something good." After we receive the reward, the value is quickly updated. If there is a bonus in the paycheck, this higher value will be reflected in striatal activity. If the cake is disappointing, the decreased value will be tracked so that next time our expectations will be lower.
In our experiment, after a decision was made between two destinations, the caudate nucleus rapidly updated its signal. Before choosing, it might signal "thinking of something great" while imagining both Greece and Thailand. But after choosing Greece, it now broadcast "thinking of something remarkable!" for Greece and merely "thinking of something good" for Thailand.
True, sometimes we regret our decisions; our choices can turn out to be disappointing. But on balance, when you make a decision even if it is a hypothetical choice you will value it more and expect it to bring you pleasure.
This affirmation of our decisions helps us derive heightened pleasure from choices that might actually be neutral. Without this, our lives might well be filled with second-guessing. Have we done the right thing? Should we change our mind? We would find ourselves stuck, overcome by indecision and unable to move forward.
The Puzzle of Optimism
While the past few years have seen important advances in the neuroscience of optimism, one enduring puzzle remained. How is it that people maintain this rosy bias even when information challenging our upbeat forecasts is so readily available? Only recently have we been able to decipher this mystery, by scanning the brains of people as they process both positive and negative information about the future. The findings are striking: when people learn, their neurons faithfully encode desirable information that can enhance optimism but fail at incorporating unexpectedly undesirable information. When we hear a success story like Mark Zuckerberg's, our brains take note of the possibility that we too may become immensely rich one day. But hearing that the odds of divorce are almost 1 in 2 tends not to make us think that our own marriages may be destined to fail.
Why would our brains be wired in this way? It is tempting to speculate that optimism was selected by evolution precisely because, on balance, positive expectations enhance the odds of survival. Research findings that optimists live longer and are healthier, plus the fact that most humans display optimistic biases and emerging data that optimism is linked to specific genes all strongly support this hypothesis. Yet optimism is also irrational and can lead to unwanted outcomes. The question then is, How can we remain hopeful benefiting from the fruits of optimism while at the same time guarding ourselves from its pitfalls?
I believe knowledge is key. We are not born with an innate understanding of our biases. The brain's illusions have to be identified by careful scientific observation and controlled experiments and then communicated to the rest of us. Once we are made aware of our optimistic illusions, we can act to protect ourselves. The good news is that awareness rarely shatters the illusion. The glass remains half full. It is possible, then, to strike a balance, to believe we will stay healthy, but get medical insurance anyway; to be certain the sun will shine, but grab an umbrella on our way out just in case.
Adapted from The Optimism Bias, by Tali Sharot. Copyright © 2011 Tali Sharot. Reprinted with permission of Pantheon Books, a division of Random House Inc. All rights reserved.
Sharot is a research fellow at University College London's Wellcome Trust Centre for Neuroimaging.