The neuroscience of optimism - how the brain creates a rosy outlook

This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.

In 1979, a crucified Eric Idle advised movie-goers to always look on the bright side of life. It seems that he needn't have bothered. Psychological experiments have consistently shown that as a species, our minds are awash with a pervasive optimism.

We expect our future successes to overpower our past ones. Compared to an imaginary Joe Bloggs, we deem ourselves likely to live longer, more likely to have a successful career and less likely to suffer divorce or ill health. Even the most cynical of minds had a tendency for making similar, overconfident predictions.

Now, Tali Sharot and colleagues form New York University have pinpointed a neural circuit in the brain that generates this glass-half-full outlook.

Sharot asked 18 recruits to remember past events or imagine future ones based on on-screen cues (such as "the end of a relationship" or "winning an award"). She then asked them to describe their imaginings along several different lines, like how positive, vivid and emotionally affecting they were, and whether they experienced the event first-hand or observed it from afar. Finally, each person completed a standard questionnaire to score how optimistic they are.

Their thoughts bore the clear signs of an optimistic bias. They rated future happy events more positively than past ones and they imagined that these windfalls would happen much sooner than negative events would. They also conjured up happy future events from a first-hand viewpoint, while they were more likely to see sad future events from an outsider's perspective.

While the volunteers daydreamed away, Sharot was busy scanning their brains with a technique called functional magnetic resonance imaging (fMRI). She identified two parts of the brain that were more strongly activated when they envisaged positive future events compared to negative ones - the rostral anterior cingulated cortex, or RACC, and the right amygdala.

The amygdala is the link between our emotions and our higher brain functions like memory and decision-making. It paints our memories with emotional colours and Sharot thinks that her data shows that it also allows us to simulate the emotional events of tomorrow.

The amygdala's contributions are moderated by the RACC, a region previously linked to acts of self-reflection, like thinking about preferences, hopes or dreams. Sharot's brain scans revealed that the RACC and amygdala were strongly linked when volunteers imaginied happy future events, but not negative ones. And the RACC was more strongly activated in volunteers who scored higher in the optimism questionnaire.

Sharot believes that the RACC helps us to imagine a future event by assessing and summing up the emotions and experiences from out past. But it puts a positive spin on things and tunes down any negative emotional responses from the amygdala. Thanks to the RACC, our past may be writ, but our future is a blank slate where we can happily distance ourselves from negative experiences and move towards positive ones.

Seeing the future through rose-tinted glasses may be a bit naïve, but it's also adaptive. A tendency to expect successful outcomes could provide us with a greater impetus for achieving our goals. While extreme optimism can lead us to harm by underestimating risks, giving too much credence to negative predictions can impair our daily lives.

By identifying the neural circuits involved in optimism, Sharot may also have shed some light on its opposite number - depression. Depression is associated with pessimism and an inability to view the future in detail. It could be that the circuit connecting the RACC to the amygdala is faulty is the brains of depressed people, so that they cannot downplay negative experiences when thinking about the future.

For more on the science of happiness, have a look at Daniel Gilbert's superlative book Stumbling on Happiness

More on optimism:

• The peril of positive thinking - why positive messages hurt people with low self-esteem

Reference: Sharot, Riccardi, Raio & Phelps. 2007. Neural mechanisms mediating optimism bias. Nature doi:10.1038/nature06280