If you want to know what goes on in your brain as you "think", and you can only read one of the flood of recent books on the subject, you can not do better than Daniel Kahneman's Thinking, Fast and Slow. It is a fascinating, rich, and eminently readable compendium of what Kahneman and others have learned about how the mind works. Truly a landmark book. But something's missing.
Kahneman describes a vast body of knowledge about how we make choices in general, and why our choices often seem to fly in the face of what would make the most sense. But he fails to describe the discoveries, made in large part by many of his colleagues and students, about the psychology of risk perception... the way we make choices about threats to our health. What we've learned about how the mind works when we face potential health risks is an important body of knowledge helpful to anyone who wants to make wiser, healthier choices, the kinds of decision making Kahneman has written his book, and devoted his career, to help us with. Thinking is a certain classic that millions will learn from, so it's a shame that this area isn't included.
To be fair, many of the cognitive tools (heuristics and biases) that we use for all sorts of decision making also influence our choices about risk. Mental shortcuts that Kahneman describes, like The Availability Heuristic and Loss Aversion and Optimism Bias, which were revealed in research about decision making that had an economic focus (Kahneman won the Nobel Prize in Economics in 2002 for this work), help us combine slow conscious thinking with faster gut instinct to make choices about money or risk or politics or lots of other things. But in addition, a distinct set of psychological tools have been discovered that help us gauge what's scary and what's not, tools that, like all heuristics and biases, usually produce reasonable choices, but which sometimes lead to perceptions and behaviors that don't match the evidence... in ways that get us into serious trouble. Almost none of that research is mentioned in Kahenman's book.
- Control -- The more control we feel we have, the less frightening a risk will feel. The less control we feel, the more afraid we'll be.
- Dread -- The nastier the nature of the risk -- the more pain and suffering it involves - the scarier it is. (This goes a long way toward explaining why cancer, the number two killer in America, is far and away the disease people fear most.)
- Is the risk Natural or Human-made -- Natural risks, like cancer-causing radiation from the sun or the toxic effects of some herbal medicines, scare us less than human-made risks, like cancer-causing radiation from nuclear power or industrial pesticides on fruits and vegetables.
- Personification -- A risk represented by a name or a face (the starving child, a dead soldier in a flag-draped coffin) affects us more powerfully than a risk that may be much larger but is only represented by impersonal numbers ("millions of starving children", statistics of battle deaths).
- Catastrophic risks (lots of harm from one large event, like a terrorist attack) worry us more than chronic risks where the harm is spread out over space and time (major killers like heart disease and drunk driving).
- Risks imposed on us (radiation from a nuclear power plant leak) feel worse than the same risk if we take it voluntarily (a chest x ray or CAT scan).
- Risks that are more immediate scare us more than risks that may be much larger but which are delayed (climate change... OOPS!)
There are more than a dozen discrete psychological risk perception factors that contribute to what Slovic and Anne Finucane and others have labeled "the Affect Heuristic", their label for how we subconsciously combine the facts and how those facts feel, based on the risk perception factors as well as our experience and education and life circumstances and other emotional inputs, to come up with the judgments we make about risk. The Affect Heuristic wonderfully captures the inescapable reality Kahneman's own work helps make indisputably clear, that despite our hubris about how smart we are, our thinking is actually a mix of intellect and instinct, reason and gut reaction, cognition and intuition. But the Affect Heuristic is only briefly described in Thinking, Fast and Slow, and none of the specific discoveries about the psychology of health risk decision making is mentioned.
This is not a criticism of Thinking Fast and Slow, which is rich and comprehensive and, understandably, focuses on the fields that were central to Kahneman's research. This is a case for greater awareness of what we've learned about how we think about health risk, a body of knowledge that can help individuals and policy makers make judgments about risk more intelligently. In his conclusion, Kahneman rightly observes that a more 'precise vocabulary' about the heuristics and biases of decision making -- the 'Endowment Effect' and 'Loss Aversion' and all the mental tools that shape the judgments we make -- can help us make smarter choices. It is perhaps even more urgent that we recognize 'Control' and 'Natural v Human-Made' and 'Personification' and all the specific risk perception factors Slovic et.al. have labeled, if we want to make more thoughtful, and healthier, decisions, about risks to our health and safety.
For much richer reading about the details of the psychology of risk perception;
"The Perception of Risk", a collection of the seminal research papers into the psychology of risk perception, including many of the papers by Slovic, Fischhoff, Lichtenstein, and others.
"The Feeling of Risk", a collection of newer research papers on risk perception, edited by Slovic.
"How Risky Is it, Really? Why Our Fears Don't Always Match the Facts", a book written for the general public, students, and policy makers, that describes not only what psychology has found, but also what neuroscience, sociology, anthropology, and media studies have discovered about the way we perceive and respond to risk the way we do. Written by David Ropeik. (Me.) As a journalist and student, and proselytizer, of this knowledge, I was deeply honored that Paul Slovic found How Risky Is It, Really? "excellent", and "comprehensive". So this doesn't come across as too self-serving, major portions of the book - the Introduction, Chapter 3 (which goes into detail about the risk perception factors introduced above), and Chapter 5, are online, free, at http://dropeik.com/how_excerpt.html)