The Marshmallow Test

INTRODUCTION

AS BOTH MY STUDENTS and my children can testify, self-control does not come naturally to me. I have been known to call my students in the middle of the night to ask how the latest data analysis was going, though it began only that evening. At dinners with friends, to my embarrassment my plate is often the first to be clean, when others are far from done. My own impatience, and the discovery that self-control strategies can be learned, has kept me studying those strategies for a lifetime.

The basic idea that drove my work and motivated me to write this book was my belief, and the findings, that the ability to delay immediate gratification for the sake of future consequences is an acquirable cognitive skill. In studies initiated half a century ago, and still ongoing today, we've shown that this skill set is visible and measurable early in life and has profound long-term consequences for people's welfare and mental and physical health over the life span. Most important, and exciting for its educational and child-rearing implications, it is a skill open to modification, and it can be enhanced through specific cognitive strategies that have now been identified.

The Marshmallow Test and the experiments that have followed over the last fifty years have helped stimulate a remarkable wave of research on self-control, with a fivefold increase in the number of scientific publications just within the first decade of this century. In this book I tell the story of this research, how it is illuminating the mechanisms that enable self-control, and how these mechanisms can be harnessed constructively in everyday life.

It began in the 1960s with preschoolers at Stanford University's Bing Nursery School, in a simple study that challenged them with a tough dilemma. My students and I gave the children a choice between one reward (for example, a marshmallow) that they could have immediately, and a larger reward (two marshmallows) for which they would have to wait, alone, for up to 20 minutes. We let the children select the rewards they wanted most from an assortment that included marshmallows, cookies, little pretzels, mints, and so on. "Amy," for example, chose marshmallows. She sat alone at a table facing the one marshmallow that she could have immediately, as well as the two marshmallows that she could have if she waited. Next to the treats was a desk bell she could ring at any time to call back the researcher and eat the one marshmallow. Or she could wait for the researcher to return, and if Amy hadn't left her chair or started to eat the marshmallow, she could have both. The struggles we observed as these children tried to restrain themselves from ringing the bell could bring tears to your eyes, have you applauding their creativeness and cheering them on, and give you fresh hope for the potential of even young children to resist temptation and persevere for their delayed rewards.

What the preschoolers did as they tried to keep waiting, and how they did or didn't manage to delay gratification, unexpectedly turned out to predict much about their future lives. The more seconds they waited at age four or five, the higher their SAT scores and the better their rated social and cognitive functioning in adolescence. At age 27–32, those who had waited longer during the Marshmallow Test in preschool had a lower body mass index and a better sense of self-worth, pursued their goals more effectively, and coped more adaptively with frustration and stress. At midlife, those who could consistently wait ("high delay"), versus those who couldn't ("low delay"), were characterized by distinctively different brain scans in areas linked to addictions and obesity.

What does the Marshmallow Test really show? Is the ability to delay gratification prewired? How can it be taught? What is its downside? This book speaks to these questions, and the answers are often surprising. In The Marshmallow Test, I discuss what "willpower" is and what it is not, the conditions that undo it, the cognitive skills and motivations that enable it, and the consequences of having it and using it. I examine the implications of these findings for rethinking who we are; what we can be; how our minds work; how we can—and can't—control our impulses, emotions, and dispositions; how we can change; and how we can raise and educate our children.

Everybody is eager to know how willpower works, and everybody would like to have more of it, and with less effort, for themselves, their children, and their relatives puffing on cigarettes. The ability to delay gratification and resist temptations has been a fundamental challenge since the dawn of civilization. It is central to the Genesis story of Adam and Eve's temptation in the Garden of Eden, and a subject of the ancient Greek philosophers, who named the weakness of the will akrasia. Over the millennia, willpower was considered an immutable trait—you either had it or you didn't—making those low in willpower victims of their biological and social histories and the forces of the momentary situation. Self-control is crucial for the successful pursuit of long-term goals. It is equally essential for developing the self-restraint and empathy needed to build caring and mutually supportive relationships. It can help people avoid becoming entrapped early in life, dropping out of school, becoming impervious to consequences, or getting stuck in jobs they hate. It is the "master aptitude" underlying emotional intelligence, essential for constructing a fulfilling life. And yet, despite its evident importance, it was excluded from serious scientific study until my students and I demystified the concept, created a method to study it, showed its critical role for adaptive functioning, and parsed the psychological processes that enable it.

Public attention to the Marshmallow Test increased early in this century and keeps escalating. In 2006, David Brooks devoted an editorial to it in the Sunday New York Times, and years later in an interview he conducted with President Obama, the president asked Brooks if he wanted to talk about marshmallows. The test was featured in The New Yorker in a 2009 Department of Science article, and the research is widely presented in television programs, magazines, and newspapers throughout the world. It is even guiding the efforts of Sesame Street's Cookie Monster to master his impulse to voraciously devour cookies so that he may join the Cookie Connoisseurs Club. The marshmallow research is influencing the curriculum in many schools that teach a wide range of children, from those living in poverty to those attending elite private academies. International investment companies use it to encourage retirement planning. And a picture of a marshmallow has become an immediately understood opener to launch discussions of delay of gratification with almost any audience. In New York City, I see kids coming home from school wearing T-shirts that say Don't Eat the Marshmallows and large metal buttons declaring I Passed the Marshmallow Test. Fortunately, as the public interest in the topic of willpower increases, so does the amount and depth of scientific information on how delay of gratification and self-control are enabled, both psychologically and biologically.

In order to understand self-control and the ability to delay gratification, we need to grasp not only what enables it but also what undoes it. As in the parable of Adam and Eve, we see headline after headline that reveals the latest celebrity—a president, a governor, another governor, a revered judge and moral pillar of society, an international financial and political wizard, a sports hero, a film star—who blew it with a young intern, a housekeeper, or an illegal drug. These people are smart, and not just in their IQ intelligence but emotional and social intelligence as well—otherwise they could not have achieved their eminence. Then why do they act so stupid? And why do they have so much company in the many men and women who never make it into the headlines?

I draw on findings at the vanguard of science to try to make sense of this. At the heart of the story are two closely interacting systems within the human brain, one "hot"—emotional, reflexive, unconscious—and the other "cool"—cognitive, reflective, slower, and effortful. The ways in which these two systems interact in the face of strong temptations underlie how preschoolers deal with marshmallows and how willpower works, or doesn't. What I learned changed my long-held assumptions about who we are, the nature and expressions of character, and the possibilities for self-generated change.

Part I, Delay Ability: Enabling Self-Control, tells the story of the Marshmallow Test and the experiments that showed preschool children doing what Adam and Eve could not do in the Garden of Eden. The results identified the mental processes and strategies through which we can cool hot temptations, delay gratification, and achieve self-control. They also pointed to possible brain mechanisms that enable these achievements. Decades later, a flood of brain research is using cutting-edge imaging techniques to probe the mind-brain connections and help us understand what the preschooler managed to do.

The marshmallow findings inevitably lead to the question "Is self-control prewired?" Recent discoveries in the science of genetics are providing fresh answers to that question. They are revealing the surprising plasticity of our brains and transforming how we think about the role of nurture and DNA, environment and heredity, and the malleability of human nature. The implications go far beyond the science lab and contradict widely shared beliefs about who we are.

Part I leaves us with a mystery: why does the preschooler's ability to wait for more treats, rather than ring the bell and settle for less, predict so much about future success and well-being? I answer that question in Part II, From Marshmallows in Pre-K to Money in 401(k), where I look at how self-control ability influences the journey from preschool to retirement planning, how it paves the way to creating successful experiences and positive expectations—an "I think I can!" mind-set and a sense of self-worth. While not guaranteeing success and a rosy future, self-control ability greatly improves the chances, helping us make the tough choices and sustain the effort needed to reach our goals. How well it works depends not just on skills but on internalizing goals and values that direct the journey, and on motivation that is strong enough to overcome the setbacks along the route. How self-control can be harnessed to build such a life by making willpower less effortful and increasingly automatic and rewarding is the story of Part II, and like life itself it unfolds in unexpected ways. I discuss not just resistance to temptation but diverse other self-control challenges, from cooling painful emotions, overcoming heartbreak, and avoiding depression to making important decisions that take future consequences into account. And while Part II shows the benefits of self-control, it makes its limits equally clear: a life with too much of it can be as unfulfilling as one with too little.

In Part III, From Lab to Life, I look at the implications of the research for public policy, focusing on how recent educational interventions beginning in preschool are incorporating lessons on self-control in order to give those children living under conditions of toxic stress a chance to build better lives. I then summarize the concepts and strategies examined throughout this book that can help with everyday self-control struggles. The final chapter considers how findings about self-control, genetics, and brain plasticity change the conception of human nature, and the understanding of who we are and what we can be.

In writing The Marshmallow Test, I imagined myself having a leisurely conversation with you, the reader, much like the many I have had with friends and new acquaintances, sparked by the question "What's the latest in the marshmallow work?" Soon we veer off into how the findings relate to aspects of our own lives, from child rearing, hiring new staff, and avoiding unwise business and personal decisions to overcoming heartbreak, quitting smoking, controlling weight, reforming education, and understanding our own vulnerabilities and strengths. I have written the book for those of you who, like me, have struggled with self-control. I've also written it for those who simply would like to understand more deeply how our minds work. I hope The Marshmallow Test will start some new conversations for you.