Paul Dirac was one of the greatest physicists of the 20th century. A pioneer in quantum theory, which shaped our modern world, Dirac was a genius when it came to analytical thinking. But when his colleagues asked him for advice, his secret to success had nothing to do with the traditional scientific method: Be guided, Dirac told them, "by your emotions."
Why would the cold logic of theoretical physics benefit from emotion? Physics' theories are expressed in mathematics, which is governed by a set of rules. But physicists don't just study existing theories--they invent new ones. In order to make discoveries, they have to pursue roads that feel exciting and avoid those that they fear will lead nowhere. They have to be brave enough to question assumptions and confident enough to present their conclusions to their skeptical colleagues. Dirac recognized that the best physicists are comfortable letting emotion guide their decisions.
Dirac's advice--like his physics--ran against the common assumption of psychology in his day: that rational thought primarily drives our behavior, and that when emotions play a role, they are likely to deflect us from our best judgment.
Today researchers have gained a deeper understanding of emotion and how it can positively influence logical choices. Consider a study led by Mark Fenton-O'Creevy, a professor at the Open University Business School, in England. Fenton-O'Creevy and his colleagues conducted interviews with 118 professional traders and 10 senior managers at four investment banks. The experimenters found that even among the most-experienced traders, the lower-performing ones seemed less likely to effectively engage with the emotions guiding their choices--whether to buy or sell a set of securities, for example, with millions of dollars at stake. The most-successful traders, however, were particularly likely to acknowledge their emotions, and followed their intuitive feelings about stock options when they had limited information to draw on. They also understood that when emotions become too intense, toning them down can be necessary. The issue for the successful traders was not how to avoid emotion but how to harness it.
One way emotions aid decision making is by steering attention to both threats and opportunities. Consider the role that disgust plays in encoding your experience of foods that could sicken you. If you're about to slurp down an oyster and you notice worms crawling all over it, you don't stop and consciously analyze the details of that situation; you just gag and throw it down. The traders, similarly, have to know what to prioritize and when to act--and they have to do it quickly. "People think if you have a Ph.D. you will be very good, because you have an understanding of options theory, but this is not always the case," said one of the investment-bank managers the researchers interviewed. You have to also have good gut instincts, and those gut instincts are largely rooted in emotion.
In the past decade, scientists have begun to understand precisely how emotions and rationality act together. The key insight is that before your rational mind processes any information, the information must be selected and evaluated. That's where emotion plays a dominant role. Each emotion--fear, disgust, anger--causes certain sensory data, memories, knowledge, and beliefs to be emphasized, and others downplayed, in your thought processes.
Imagine you're walking up a dark street in a relaxed state, looking forward to dinner and a concert later that evening. You may be aware of being hungry and may not register small movements in the shadows ahead, or the sound of footsteps behind you. Most of the time, ignoring those things is fine; the footsteps behind you are probably other pedestrians traveling to their own evening plans, and the movements in the shadows could just be leaves blowing in the wind. But if something triggers your fear, those sights and sounds will dominate your thinking; your sense of hunger will vanish, and the concert will suddenly seem unimportant. That's because when you are in a "fear mode" of processing, you focus on sensory input; your planning shifts to the present, and your goals and priorities change. You might adjust your route to one that takes longer but is better lit, sacrificing time for safety.
In one illustrative study, researchers induced fear in their subjects by sharing a grisly account of a fatal stabbing. They then asked these participants to estimate the probability of various calamities, including other violent acts and natural disasters. Compared with subjects whose fear had not been activated, these subjects had an inflated sense of the probability of those misfortunes--not only related incidents, such as murder, but also the unrelated, such as tornadoes and floods. The gruesome stories affected the subjects' mental calculus on a fundamental level, making them generally warier of environmental threats. In the world outside the laboratory, that wariness pushes you to avoid dangerous situations.
The ways in which our emotions influence our judgment aren't always clear to us. In a study on disgust, for instance, scientists showed volunteers either a neutral film clip or a scene from Trainspotting in which a character reaches into the bowl of a filthy toilet. One of the characteristics of disgust is a tendency toward disposal, whether of food or other items. After playing the clips, the researchers gave the subjects the opportunity to trade away one box of unidentified office supplies for another--and found that 51 percent of those who had seen the Trainspotting clip exchanged their box, compared with 32 percent of participants who'd watched the neutral clip. But when quizzed about their decision afterward, the disgusted participants tended to justify their actions with "rational" reasons.
Welcoming emotion into the decision-making process can help us be more clear-eyed about where our choices come from. Dirac knew that emotion helped him look beyond the beliefs of his contemporaries. Again and again, his controversial ideas proved correct. He invented a mathematical function that seemed to violate the basic rules of the subject--but that was eventually embraced and developed by later mathematicians. He predicted a new type of matter, called antimatter--another idea that was revolutionary at the time but is widely embraced today. And his appreciation for the role of emotion was prescient in itself. Dirac died in 1984, a couple of decades before the revolution in emotion theory began, but he'd no doubt have been happy to see that he'd been right again.
This article was adapted from Leonard Mlodinow's forthcoming book, Emotional: How Feelings Shape Our Thinking.