Human Brain Hardwired For Optimism

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Some memories evoked in the study were vivid, she said, such as those of the terrorist attacks against the World Trade Center on September 11, 2001. Other memories were neutral, such as getting a haircut.

Vivid memories "lit up" the amygdala and the rostral anterior cingulated cortex. Negative reminiscences caused much less energetic activity in these areas of the brain, which are important to regulating emotions.

Curiously, the same thing happened when subjects contemplated future actions, suggesting that the brain in most people may mute the effect of anticipating potentially upsetting events.

When subjects who were scanned filled out questionnaires after the tests, they reported feeling optimistic about future events, and that they imagined them happening more vividly and sooner than potentially negative events.

This happened even for seemingly banal events. "When we asked people about projecting a haircut in the future, this neutral event became the best haircut ever-never looked better, and met a cute guy at the hairdressing salon," according to the study.

One possible explanation is that optimism became an evolutionary advantage for humans, though Phelps cautions that the amygdala and rACC developed in evolution long before humans appeared. This means that other animals may share some aspects of this rose-tinting of future activities.

No one has yet compared humans' optimism to that of other animals that I know of, although it is possible that the two regions of the brain involved in this phenomenon are modulated in humans by the more recently evolved frontal-cortex centers of the brain responsible for high reasoning, motivation, and decisionmaking.

Other fMRI scans for emotions such as fear and anxiety-which cause a flurry of activity in the amygdala-have shown that the reasoning centers of the brain in the frontal lobe activate and appear to interact with these older regions to influence and modulate behavior.

As with many fMRI studies that focus on small groups of volunteers in universities, it's possible that the subjects at N.Y.U. were biased toward optimistic souls, and that there is an equally pervasive tendency among some people to be pessimistic. Researchers have found that some people suffering from depression have malfunctioning amygdalas and rACCs.

Phelps told me that being overly optimistic is also dangerous-which may explain how we humans sometimes have willfully ignored or diminished the impact of our own actionseven when they cause us harm in the future. This includes the rise of carbon dioxide in the atmosphere linked to global warming. "Pessimistic" scientists raised the alarm about this as early as the 1970s, but society only recently has accepted the reality.

Then again, sitting here in Northern California, the optimists in Silicon Valley are already proclaiming—with their amygdalas and rACCs undoubtedly raging—that human ingenuity can fix the global-warming problem as surely as we created the fossil-burning contraptions spewing greenhouse gases in the first place.

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