How We Decide

Jonah Lehrer, a science writer, examines how the human brain makes decisions, drawing on neuroscience, psychology, and real-world case studies to challenge the Western assumption that rationality is the highest form of thought. His central thesis is that good decision-making requires both emotional and rational brain systems, and the key is knowing when to deploy each.

Lehrer opens with his experience in a flight simulator near Montreal, where he faces an engine fire while landing a Boeing 737. On his first attempt, he descends to gain speed and lands safely; on his second, he climbs and crashes. This scenario frames the book's core question: What happens inside the brain when we decide? Lehrer argues that the Western intellectual tradition, from Plato through Descartes and Freud, has cast emotion as an obstacle to good thought. Neuroscience, he contends, reveals this picture is wrong.

His first major case study is quarterback Tom Brady's game-winning drive in the 2002 Super Bowl. Brady, a lightly regarded draft pick, read defensive formations and found open receivers in fractions of a second, far too fast for conscious deliberation. The NFL's Wonderlic intelligence test showed virtually no correlation with quarterback success: Hall of Famers scored poorly, while high scorers struggled on the field. To explain why emotion-driven cognition can be so effective, Lehrer introduces neurologist Antonio Damasio's research on a patient called Elliot, whose frontal-lobe surgery left his IQ intact but destroyed his ability to feel emotion. Elliot became pathologically indecisive, and his life collapsed. Damasio found the same pattern in other patients with damage to the orbitofrontal cortex, a brain region that connects visceral emotions to conscious thought. Without emotional input, even basic decisions become impossible.

Lehrer traces this emotional intelligence to the brain's dopamine system. He recounts how Lieutenant Commander Michael Riley, aboard the HMS Gloucester during the 1991 Gulf War, detected a radar blip heading toward the USS Missouri that looked identical to returning American fighter jets. With no definitive data, Riley felt an inexplicable dread and ordered two missiles fired; the target proved to be an Iraqi Silkworm missile. Cognitive psychologist Gary Klein later discovered that the Silkworm appeared on radar eight seconds later than a fighter jet would have. Riley's dopamine neurons had unconsciously registered this discrepancy and translated it into fear. Drawing on Wolfram Schultz's research at Cambridge University, Lehrer explains that dopamine neurons generate predictions and measure the gap between expectation and reality. When predictions fail, the anterior cingulate cortex, dense with rare spindle neurons, broadcasts error signals across the brain, gradually converting patterns into feelings. This learning process requires deliberate practice: world champion backgammon player Bill Robertie attributed his success to obsessively reviewing his mistakes, and psychologist Carol Dweck's research showed that children praised for effort improved while those praised for innate intelligence regressed.

Having established the power of emotions, Lehrer identifies conditions that cause the emotional brain to fail. He profiles Ann Klinestiver, a teacher with Parkinson's disease whose dopamine-boosting medication triggered a devastating gambling addiction. Slot machines exploit the dopamine system because their random payouts prevent neurons from finding a pattern, generating fresh surges of pleasure with each win. The same flaw explains the "hot hand" illusion in basketball: psychologists Amos Tversky and Thomas Gilovich found no statistical evidence for shooting streaks, yet 91 percent of fans believed in them. This pattern-seeking tendency also distorts financial decisions. Neuroscientist Read Montague's experiments showed that dopamine-driven regret over missed gains caused investors to chase simulated stock-market bubbles and panic-sell during crashes. Daniel Kahneman and Tversky's discovery of loss aversion, the finding that the pain of losing is roughly twice as intense as the pleasure of gaining, compounds the problem. Credit cards exploit these biases further by making transactions abstract: brain-imaging experiments showed that paying with plastic reduced activity in the insula, a region associated with the pain of spending, and an MIT experiment found credit card bids were twice as high as cash bids for the same item.

Lehrer then makes the case for rationality. He recounts the 1949 Mann Gulch fire, where smokejumper Wag Dodge, trapped by a wall of flame, stopped running, lit an escape fire, and lay down in the ashes while 13 of his crew died fleeing. Dodge survived by overriding panic with deliberate thought from his prefrontal cortex, the most recently evolved brain region, responsible for abstract reasoning and impulse control. Walter Mischel's marshmallow experiment reinforced this point: four-year-olds who used cognitive strategies to delay gratification scored 210 points higher on the SAT as teenagers. The most dramatic example is United Airlines Flight 232. In 1989, Captain Al Haynes lost all three hydraulic systems on a DC-10 and invented a new steering technique using differential engine thrust, saving 184 passengers. In subsequent simulations, other pilots failed to replicate the landing on their first 57 attempts.

Yet rationality has sharp limits. Opera singer Renee Fleming developed chronic performance anxiety when conscious self-monitoring disrupted her technique, and golfer Jean Van de Velde lost the 1999 British Open by overthinking his swing. Psychologist Sian Beilock's research confirmed that experienced athletes performed worse when forced to analyze automatic movements. Timothy Wilson's experiments showed that college students who analyzed their preferences reversed expert jam rankings, and Ap Dijksterhuis found that for complex purchases, subjects distracted by puzzles chose better than those who deliberated. The conscious mind handles only about seven pieces of information at once, and when overwhelmed, it fixates on misleading variables.

Lehrer devotes a chapter to moral decision-making, arguing it is fundamentally emotional. He examines psychopathy as a condition defined by damaged emotional circuitry: people with the condition have intact reasoning but cannot generate empathy or remorse. Neuroscientist Joshua Greene's trolley experiments revealed that people will redirect a trolley to save five lives at the cost of one but will not physically push someone to death for the same result, because the personal scenario activates brain areas that simulate others' feelings.

The brain, Lehrer argues, makes decisions through internal arguments between competing neural systems, and prematurely silencing this debate leads to disaster. Philip Tetlock's 20-year study of 284 political pundits found they performed worse than chance, with the most certain being the least accurate. The 1973 Yom Kippur War illustrates the danger: Israeli intelligence chief Eli Zeira clung to a theory that Egypt would not attack, dismissing massive contrary evidence. The surprise invasion nearly destroyed Israel, and the postwar commission created an independent analytical branch to ensure that military intelligence would never again be dominated by a single perspective.

Lehrer synthesizes his arguments through professional poker player Michael Binger, a physicist who uses probability for straightforward hands but shifts to emotional reads for complex ones. Dijksterhuis's car-shopping experiment confirmed this principle: conscious analysis outperformed intuition for simple decisions with few variables, but unconscious processing proved far superior for complex ones with many variables. Lehrer presents a practical taxonomy: use reason for simple and novel problems, trust trained emotions for complex choices, embrace uncertainty rather than forcing consensus, and above all, practice metacognition, the habit of monitoring which cognitive strategy fits the situation at hand.

In the coda, Lehrer shows how the aviation industry applied these principles. Flight simulators trained pilots' emotional brains through experience and structured error review, while Cockpit Resource Management ended the captain's unchallenged authority and required open dissent. These innovations cut pilot-error crashes by 71 percent. The modern cockpit, with its redundant computers monitored by attentive pilots, models the ideal relationship between emotional and rational systems: Neither is infallible, but mutual correction keeps errors from compounding.