The part of our brain that leaps to conclusions like this is called the adaptive unconscious. Our unconscious is a powerful force. But it's fallible. It's not the case that our internal computer always shines through, instantly decoding the "truth" of a situation. It can be thrown off, distracted, and disabled. Our instinctive reactions often have to compete with all kinds of other interests and emotions and sentiments. When our powers of rapid cognition go awry, they go awry for a very specific and consistent set of reasons, and those reasons can be identified and understood. It is possible to learn when to listen to that powerful onboard computer and when to be wary of it. Just as we can teach ourselves to think logically and deliberately, we can also teach ourselves to make better snap judgments.

Thin-slicing refers to the ability of our unconscious to find patterns in situations and behavior based on very narrow slices of experience. Thin-slicing is not an exotic gift. It is a central part of what it means to be human. We thin-slice whenever we meet a new person or have to make sense of something quickly or encounter a novel situation. We thin-slice because we have to, and we come to rely on that ability because there are lots of hidden fists out there, lots of situations where careful attention to the details of a very thin slice, even for no more than a second or two, can tell us an awful lot.

Snap judgments and rapid cognition take place behind a locked door. If we are to learn to improve the quality of the decisions we make, we need to accept the mysterious nature of our snap judgments. We need to respect the fact that it is possible to know without knowing why we know and accept that -- sometimes -- we're better off that way.

What we think of as free will is largely an illusion: much of the time, we are simply operating on automatic pilot, and the way we think and act -- and how well we think and act on the spur of the moment -- are a lot more susceptible to outside influences than we realize.

This is the price we pay for the many benefits of the locked door. When we ask people to explain their thinking -- particularly thinking that comes from the unconscious -- we need to be careful in how we interpret their answers. We learn by example and by direct experience because there are real limits to the adequacy of verbal instruction.

The Dark Side of Thin-Slicing

Our attitudes toward things like race or gender operate on two levels. First of all, we have our conscious attitudes. This is what we choose to believe. These are our stated values, which we use to direct our behavior deliberately. Then there's our racial attitude on an unconscious level -- the immediate, automatic associations that tumble out before we've even had time to think. We don't deliberately choose our unconscious attitudes. We may not even be aware of them. The giant computer that is our unconscious silently crunches away.

Our first impressions are generated by our experiences and our environment, which means that we can change our first impressions -- we can alter the way we thin-slice -- by changing the experiences that comprise those impressions. Taking rapid cognition seriously -- acknowledging the incredible power, for good and ill, that first impressions play in our lives -- requires that we take active steps to manage and control those impressions.

Creating Structure for Spontaneity

Spontaneity isn't random. How good people's decisions are under the fast-moving, high-stress conditions of rapid cognition is a function of training and rules and rehearsal.

We take it as a given that the more information decision makers have, the better off they are. But what does the Goldman algorithm say? Quite the opposite: that all that extra information isn't actually an advantage at all; that, in fact, you need to know very little to find the underlying signature of a complex phenomenon. All you need is the evidence of the ECG, blood pressure, fluid in the lungs, and unstable angina. In fact -- and this is a key point in explaining the breakdown of Blue Team that day in the Gulf -- that extra information is more than useless. It's harmful. It confuses the issues.

• Truly successful decision-making relies on a balance between deliberate and instinctive thinking. Deliberate thinking is a wonderful tool when we have the luxury of time, the help of a computer, and a clearly defined task, and the fruits of that type of analysis can set the stage for rapid cognition.

• In good decision making, frugality matters. To be a successful decision maker, we have to edit.

Expert First Impressions

The first impressions of experts are different. By that I don't mean that experts like different things than the rest of us -- although that is undeniable. When we become expert in something, our tastes grow more esoteric and complex. What I mean is that it is really only experts who are able to reliably account for their reactions. Our unconscious reactions come out of a locked room, and we can't look inside that room. But with experience we become expert at using our behavior and our training to interpret -- and decode -- what lies behind our snap judgments and first impressions.

Whenever we have something that we are good at -- something we care about -- that experience and passion fundamentally change the nature of our first impressions. This does not mean that when we are outside our areas of passion and experience, our reactions are invariably wrong. It just means that they are shallow. They are hard to explain and easily disrupted. They aren't grounded in real understanding.

Mind Reading

We take it as a given that first we experience an emotion, and then we may -- or may not -- express that emotion on our face. We think of the face as the residue of emotion. What this research showed, though, is that the process works in the opposite direction as well. Emotion can also start on the face. The face is not a secondary billboard for our internal feelings. It is an equal partner in the emotional process.

Our voluntary expressive system is the way we intentionally signal our emotions. But our involuntary expressive system is in many ways even more important: it is the way we have been equipped by evolution to signal our authentic feelings.

• Arousal leaves us mind-blind.

• I think that we become temporarily autistic also in situations when we run out of time. "When we make a split-second decision," Payne says, "we are really vulnerable to being guided by our stereotypes and prejudices, even ones we may not necessarily endorse or believe."

Our powers of thin-slicing and snap judgments are extraordinary. But even the giant computer in our unconscious needs a moment to do its work.

Our unconscious thinking is, in one critical respect, no different from our conscious thinking: in both, we are able to develop our rapid decision making with training and experience.

Lessons of Blink

• We are often careless with our powers of rapid cognition. We don't know where our first impressions come from or precisely what they mean, so we don't always appreciate their fragility. Taking our powers of rapid cognition seriously means we have to acknowledge the subtle influences that can alter or undermine or bias the products of our unconscious.

• Too often we are resigned to what happens in the blink of an eye. It doesn't seem like we have much control over whatever bubbles to the surface from our unconscious. But we do, and if we can control the environment in which rapid cognition takes place, then we can control rapid cognition.