Monday, August 10, 2009

Decisions Are Not So Simple

By: Scott A. Huettel, Ph.D.

The publisher pulled this book from distribution in March 2013. This review was published in 2009.

[Editor's note: The publisher pulled this book from distribution in March 2013. This review was published in 2009.]

 

The brain is a simplifier. When faced with a complex problem, it does not dispassionately weigh all available information before selecting a course of action. Instead, it takes in a situation, simplifies it and applies behavioral rules that have worked in the past. The brain’s ability to make a quick decision based on limited information is often remarkably efficient—for example, when a driver swerves to avoid an unexpected obstacle. Yet we also encounter many dilemmas that the brain is less equipped to confront, from mundane situations (“Should I have this slice of pie for dessert?”) to life-changing questions (“Should I quit my job and start my own business?”). For dramatic and sometimes disastrous examples of the consequences of poor decision-making, we need look no further than the current economy.

Jonah Lehrer’s new book, How We Decide, explores the way people make decisions. It builds upon a recent surge in research in behavioral economics, cognitive psychology and neuroscience, much of which challenges long-standing economic models of rational decision-making. In the book’s introduction, Lehrer sets forth his thesis: Our brains have a variety of tools for decision-making, some rational and others emotional, and good decisions come from applying the right tool in the right circumstances.

To support this thesis, Lehrer skillfully engages readers in a range of scenarios that emphasize the human character of decision-making. He introduces pilots faced with equipment failures, firefighters confronting an onrushing wall of flames, stock traders chasing market fluctuations, and Ikea shoppers bewildered by a vast selection of nearly identical couches. He then calls upon recent scientific research to explain the choices these people made. Across this diversity of content, Lehrer reveals his signal strength as a writer: an ability to link complex concepts without resorting to jargon or empty prose. He extracts meaning from a welter of complex phenomena and somehow produces a simple and coherent story.

Simplicity is not always a virtue, however, and complexity should not always be avoided. The task of the science popularizer, especially when relating cutting-edge topics like those Lehrer describes, is to simplify as much as possible without sacrificing fidelity to the original research.

Synthesizing the Brain: Reason vs. Emotion

Lehrer frames most of his examples within the dual-systems model of brain function, which echoes the ancient distinction between reason and emotion. As typically conceived, the dual-systems model suggests that our thoughts and behaviors reflect competition between two aspects of our brains. The rational system, often localized to the prefrontal cortex, supports controlled and sequential thought. The emotional system, which comprises regions such as the amygdala and the insular cortex, guides rapid, automatic and visceral reactions to stimuli. The moment-to-moment interaction of these two systems determines the extent to which our decisions are rational, emotional or both.

At first consideration, the dual-systems model seems like a reasonable account of human decision-making. In the wake of an impulse purchase or an extra piece of pie, we all have wished that we had exerted a bit more control. Given these shared experiences, many readers will find themselves nodding in self-recognition when Lehrer describes examples of irrationality: overemphasizing potential monetary losses compared with potential gains, seeing nonexistent patterns in stock fluctuations and seeking immediate pleasure at the cost of future pain. The dual-systems model allows us to ascribe these flaws to the limitations of our brains. In Lehrer’s argument, the prefrontal cortex is rational but also easy to hoodwink, and our dopamine neurons, which respond to the rewards we receive, can do just that by detecting subtle and potentially misleading patterns in the world around us. Lehrer’s conclusion: If only we could listen to our prefrontal cortices instead of our dopamine neurons!  

Unfortunately for the lay reader, Lehrer’s explanations of neuroscience lead to several problems. The first is his repeated tendency to shoehorn scientific findings into the overarching story. For example, Lehrer states that the dorsolateral prefrontal cortex, or DLPFC—the upper regions of the frontal lobes—is commonly considered to be “the rational center of the brain.” He then tells a story about Mary, an Ivy League student who seemed to have a limitless future. She suddenly became profoundly self-destructive—absent from class, impulsive, alcoholic, promiscuous and unrepentant. An MRI scan revealed that Mary had a tumor in the prefrontal cortex. The natural conclusion is that the tumor had damaged the rational part of her brain. But hidden in this example is a subtle distortion: Self-destructive behavior such as Mary’s is often a hallmark of damage to a different brain area—the ventromedial prefrontal cortex, or VMPFC, at the base of the frontal lobes. In contrast, DLPFC damage more commonly leads to an apathetic, disinterested state called abulia.

Why does it matter which part of the prefrontal cortex links to self-destructive behavior? Tumors can cause damage to both the VMPFC and the DLPFC, after all. Even if Lehrer glosses over the details, some part of the brain must be our rational center, right? Neuroethicists refer to this sort of simplified reasoning as “neurorealism”—the power of neuroscience data to make claims seem more real. Because he neatly maps our decision-making processes onto specific brain regions, Lehrer’s subsequent advice seems grounded in our biology—even if he has interpreted the scientific facts to fit his story. 

A second problem is that Lehrer misses areas of current and ongoing scientific debate. Consider the problem of delayed gratification: Many difficult real-world decisions, such as choosing where to invest money, require us to forgo an immediate reward to obtain a distant but better outcome. Lehrer discusses a seminal neuroimaging study in which participants chose to receive small gift certificates immediately or larger gift certificates in a few weeks. The results were striking: Nominally “emotional” brain regions became more active when rewards were available immediately, while nominally “rational” brain regions were equally activated regardless of delay.

Based on this study alone, one might conclude that the maladaptive influence of our brain’s reward system causes impulsive choices. Several years ago, however, other neuroscientists ran a similar study and found a very different result: The activation of the brain’s reward system signaled the subjective value of the gift certificate, regardless of the delay until its delivery. This second study suggested that there is no impulsive system to push people toward immediate rewards. This debate will remain unresolved until new research reconciles the conflicting results. What is clear, however, is that the neural basis of delayed gratification is more complex than Lehrer suggests.

Lehrer makes a similar error of omission when he discusses the risky behavior of teenagers. Noting that the prefrontal cortex is still immature during adolescence, Lehrer concludes that “teens make bad decisions because they are literally less rational.” To anyone who has been around teenagers, this seems like a pretty safe statement—yet it may be wrong. Psychologist Valerie Reyna’s work has shown that teenagers are, indeed, rational in their decision-making; that is, they weigh benefits, costs, and probabilities in a manner that fits standard economic models. Where they differ from adults, according to Reyna’s research, is in their estimates about the consequences of their decisions. For instance, they underestimate the likelihood of getting pregnant following unsafe sex. These different explanations—inherent irrationality versus poor estimates of consequences—suggest very different strategies for preventing teenagers’ risky behavior.

From Brain to Behavior: Practical Advice

Like many other popular neuroscience books, How We Decide ends with practical advice. To Lehrer’s credit, he repeatedly states that no one rule for making decisions always works. Instead, the core challenge of decision-making lies in selecting a strategy that most likely will lead to an acceptable outcome. Some of these strategies can seem counterintuitive. For instance, recent studies suggest that we are more satisfied with our decisions if we distract ourselves beforehand. Here, Lehrer’s recommendations frequently hit the mark.

Even so, one recurring piece of advice is troubling. Lehrer argues that because the prefrontal cortex is slow and has limited capacity, our rational faculties are poorly suited for complex decision-making: “We often make decisions on issues that are exceedingly complicated. In those situations, it’s probably a mistake to consciously reflect on all the options, as this inundates the prefrontal cortex with too much data. . . . When choosing a couch, or holding a mysterious set of cards, always listen to your feelings” (pages 236–237).

This is good advice for the expert poker player whose well-honed intuition incorporates hundreds of thousands of prior hands. But when we bring much less expertise to a problem—as when most of us balance our portfolios or play poker—our feelings may be a very poor guide indeed. Moreover, the learning abilities of our dopamine system, which Lehrer focuses on throughout the book, are inadequate for making many complicated decisions. Specifically, when we receive feedback infrequently, in abstract form, and without immediate personal consequence, our dopamine system is ill equipped to learn from our mistakes. For example, evaluating the terms of a mortgage without conscious reflection would be a bad idea, even when intuition screams that we should buy before housing prices rise.

How We Decide works best as a series of engaging anecdotes rather than a synthesis and interpretation of research. And contrary to the book jacket, this is not “the first book to use the unexpected discoveries of neuroscience to help us make the best decisions”—see earlier popular neuroscience books by Jason Zweig and Read Montague. Recent books by behavioral economists also provide similar sorts of advice, albeit with minimal neuroscience content.

Lehrer is a gifted storyteller, but too often he falls prey to neurorealism by providing a snapshot of neuroscience data to make a phenomenon seem more vivid and compelling. Even accurate summaries may omit the most exciting parts of cutting-edge research. For example, Lehrer points out that one standard drug treatment leads to pathological gambling in some Parkinson’s patients, but he does not address the fascinating research question of what makes most patients resistant to the lure of gambling. Separately he describes the brain’s insular cortex as activated by potential losses, whereas many scientists now think of this brain area like a switch: It shapes other regions’ activity based upon the risk in the immediate environment.

Stories such as those in How We Decide reassure us. They reinforce our intuition and offer simple guidance. But the real world, in all its messy complexity, remains a far more interesting place to explore.



About Cerebrum

Bill Glovin, editor
Carolyn Asbury, Ph.D., consultant

Scientific Advisory Board
Joseph T. Coyle, M.D., Harvard Medical School
Kay Redfield Jamison, Ph.D., The Johns Hopkins University School of Medicine
Pierre J. Magistretti, M.D., Ph.D., University of Lausanne Medical School and Hospital
Robert Malenka, M.D., Ph.D., Stanford University School of Medicine
Bruce S. McEwen, Ph.D., The Rockefeller University
Donald Price, M.D., The Johns Hopkins University School of Medicine

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