If I could, I would reach beyond the cage of bone,
to touch the mind within the brain,
to reach the frightened nerves that wrap the heart;
I would speak your name there.
Our decisions make us who we are. Although we would like to think that our decisions are made rationally, deliberatively, many decisions are not. We all know that some of our decisions are made emotionally, and some are made reactively. Some have their intended consequences, and some have consequences we never imagined possible.
We are physical beings. The human brain is a complex network of neurons and other cells that takes information in from the world through its sensory systems and acts on the world through its motor systems. But how does that network of cells, in constant dynamic flux, become the person you are? How does the mind fit into that small place in the cage of bone that is our skull? How does it process information? How does it perceive the world, determine the best option, select an action, and take that action? How does it fall in love? Laugh at the overwhelming emotion of holding an infant? How does it create great art or great music? How does it feel the triumphant emotion of Beethoven’s Ode to Joy or the devastating pathos of Bob Dylan’s Knock Knock Knocking on Heaven’s Door? Just how does the lady sing the blues? How does it get addicted and how does it break that addiction? How does it have a personality? What makes you you and me me?
Fundamentally, all of these questions are about how the being that you recognize as yourself fits into this physical brain nestled in your skull. Fundamentally, these questions are about how that brain makes decisions. This book is an attempt to answer that question.
A few years ago, John Gessner, who runs a local program for people with gambling problems and their families, asked me if I would be willing to give a talk to his clients on decision-making. I had been giving talks to Jan Dubinsky’s BrainU program for high school teachers interested in neuroscience and had recently given a talk to frontline medical professionals (doctors, nurses, and addiction social workers) on my laboratory’s work identifying vulnerabilities in decision-making systems. John had heard of this talk and wanted me to present this work to his clients.
I protested that I was not a medical professional and that I could not tell them how to fix what was broken. He said that they had lots of people to tell them that, what they wanted was someone to tell them why—Why do we make the choices we do? He said they wanted to know why those decisions get made wrong, especially when they knew what the right choices were.
The lecture itself went very well. There were several dozen people in the audience, and they were involved and asking questions throughout. And then, afterwards, they had so many questions that I stayed there answering questions for hours. There was a hunger there that I had not appreciated until I met those gamblers and their families, an almost desperate desire to understand how the brain works. They had seen how things can go wrong and needed an explanation, particularly one that could explain how they could both be conscious beings making decisions and yet still feel trapped. Somehow, that science lecture on how the multiple decision-making systems interact reached them. I realized then that there was a book I had to write.
Over the past three years, this book has morphed and grown. My goal, however, remains to explain the science of how we make decisions. As such, an important part of this book will be to identify what questions remain.1 My goal is not to provide a self-help book to help you make better decisions. I am not going to tell you what you should do. Nor are the answers to curing addiction or poor decisions herein. You should check with your own medical professionals for treatment. Every individual is unique, and your needs should be addressed by someone directly familiar with them. Nevertheless, I hope that you find the book illuminating. I hope you enjoy reading it. It has been tremendously fun to write.
One of the remarkable things that has occurred over the past several decades is the convergence of different fields on the mechanisms of decision-making. Scientific fields as diverse as psychology, robotics, economics, neuroscience, and the new fields of neuroeconomics and computational psychiatry have all been converging on the recognition that decision-making arises from a complex interaction of multiple subsystems. In fact, these fields have converged on a similar categorization of the differences between the subsystems. In this book, we will explore how this convergence explains the decision-making that we (as humans) do.
I have divided this book into four sections. The first sections (Decisions and the Brain and The Decision-Making System) will lay out the work that has been done on the basic mechanisms—What is a decision? How does the brain’s decision-making system work? What are the components that make up that decision-making system? And then, the third and fourth sections will explore the consequences of that system.
The first section consists of five chapters, two chapters to set the stage (1: What Is a Decision? and 2: The Tale of the Thermostat) and three chapters to introduce the basic neuroeconomics of decision-making (3: The Definition of Value, 4: Value, Euphoria, and the Do-It-Again Signal, and 5: Risk and Reward). In the second section, we will start with the results that the decision-making system is made up of multiple modules or subsystems (Chapter 6), and then spend a chapter each on the component systems (Chapters 7 through 15).
In the third section (The Brain With a Mind of Its Own), we will explore the consequences of the physical nature of the brain, how mind and brain are related, and how vulnerabilities in the decision-making system can lead to dysfunction, such as addiction (Chapter 18), problem gambling (Chapter 19), and post-traumatic stress disorder (Chapter 20).
Finally, in the fourth section (The Human Condition), we will explore the philosophical questions of what makes us human (Chapter 22), of morality (Chapter 23), and of free will and consciousness (24: The Conundrum of Robotics) in the light of the new work on decision-making systems discussed in the previous sections.
I’ve tried to write the book so that it can be read straight through from start to finish by a reader with only a basic knowledge of neuroscience and computers; however, some readers may feel that they want a more detailed introduction to the concepts that are being discussed in this book. For those readers, I’ve included three chapters in an appendix, including What is information processing and How neurons process information (Appendix A), How we can read that information from neural signals (Appendix B), and How memories are stored (by content, not by index, Appendix C).
Throughout the book, every statement is backed up with citations. These citations will be marked with superscript numbers, matching the list in the bibliographic notes, which will then reference the actual list of citations.2 These numbers are not endnotes and will not be used to refer to any additional text; they are there only to back up the claims in the book. Instead, extra information and discussion that could distract from the flow will be put into footnotes, marked with superscript letters.A
Each chapter begins with a short poem and ends with a set of follow-up readings. In my mind, I think of the poems as contemplative moments that can be used to shape one’s perspective when reading the chapter. As a friend recovering from cancer in his hospital bed recently told me, “Sometimes you need the poetry to get to the heart of the science.” The follow-up readings at the end of each chapter are books, review articles, starting points for those who want to pursue a topic in depth. While the superscript citations will refer to the primary literature, some of which can be quite difficult to understand, the follow-up readings should be understandable by anyone reading this book.