Mastermind: How to Think Like Sherlock Holmes

by Maria Konnikova

  The greats don’t become complacent. And that, in a nutshell, is Holmes’s secret. Even though he doesn’t need anyone to walk him through the scientific method of the mind—he may as well have invented the thing—he nevertheless keeps challenging himself to learn more, to do things better, to improve, to tackle a case or an angle or an approach that he has never seen in the past. Part of this goes back to his constant enlistment of Watson, who challenges him, stimulates him, and forces him to never take his prowess for granted. And another part goes to the choice of the cases themselves. Remember, Holmes doesn’t take on just any case. He takes on only those that interest him. It’s a tricky moral code. He doesn’t take his cases merely to reduce crime but to challenge some aspect of his thinking. The commonplace criminal need not apply.

  But either way, whether in cultivating Watson’s companionship or in choosing the harder, more exceptional case over the easier one, the message is the same: keep feeding the need to learn and to improve. At the end of “The Red Circle” Holmes finds himself face-to-face with Inspector Gregson, who turns out to have been investigating the very case that Holmes decides to pursue after his initial work is done. Gregson is perplexed to the extreme. “But what I can’t make head or tail of, Mr. Holmes, is how on earth you got yourself mixed up in the matter,” he says.

  Holmes’s response is simple. “Education, Gregson, education. Still seeking knowledge at the old university.” The complexity and unrelatedness of this second crime do the opposite of deterring him. They engage him and invite him to learn more.

  In a way, that, too, is a habit, of never saying no to more knowledge, as scary or as complicated as it may be. The case in question is “a specimen of the tragic and grotesque,” as Holmes says to Watson. And as such, it is well worthy of pursuit.

  We, too, must resist the urge to pass on a difficult case, or to give in to the comfort of knowing we’ve already solved a crime, already accomplished a difficult task. Instead, we have to embrace the challenging, even when it is far easier not to. Only by doing so can we continue throughout our lives to reap the benefits of Holmesian thinking.

  The Perils of Overconfidence

  But how do we make sure we don’t fall victim to overly confident thinking, thinking that forgets to challenge itself on a regular basis? No method is foolproof. In fact, thinking it foolproof is the very thing that might trip us up. Because our habits have become invisible to us, because we are no longer learning actively and it doesn’t seem nearly as hard to think well as it once did, we tend to forget how difficult the process once was. We take for granted the very thing we should value. We think we’ve got it all under control, that our habits are still mindful, our brains still active, our minds still constantly learning and challenged—especially since we’ve worked so hard to get there—but we have instead replaced one, albeit far better, set of habits with another. In doing so we run the risk of falling prey to those two great slayers of success: complacency and overconfidence. These are powerful enemies indeed. Even to someone like Sherlock Holmes.

  Consider for a moment “The Yellow Face,” one of the rare cases where Holmes’s theories turn out to be completely wrong. In the story, a man named Grant Munro approaches Holmes to uncover the cause of his wife’s bizarre behavior. A cottage on the Munros’ property has recently acquired new tenants, and strange ones at that. Mr. Munro glimpses one of its occupants and remarks that “there was something unnatural and inhuman about the face.” The very sight of it chills him.

  But even more surprising than the mystery tenants is his wife’s response to their arrival. She leaves the house in the middle of the night, lying about her departure, and then visits the cottage the next day, extracting a promise from her husband that he will not try to pursue her inside. When she goes a third time, Munro follows, only to find the place deserted. But in the same room where he earlier saw the chilling face, he finds a photograph of his wife.

  What ever is going on? “There’s blackmail in it, or I am much mistaken,” proclaims Holmes. And the blackmailer? “The creature who lives in the only comfortable room in the place and has her photograph above his fireplace. Upon my word, Watson, there is something very attractive about that livid face at the window, and I would not have missed the case for worlds.”

  Watson is intrigued at these tidbits. “You have a theory, then?” he asks.

  “Yes, a provisional one,” Holmes is quick to reply. “But,” he adds, “I shall be surprised if it does not turn out to be correct. This woman’s first husband is in that cottage.”

  But this provisional theory proves incorrect. The occupant of the cottage is not Mrs. Munro’s first husband at all, but her daughter, a daughter of whose existence neither Mr. Munro nor Holmes had any prior knowledge. What had appeared to be blackmail is instead simply the money that enabled the daughter and the nanny to make the passage from America to England. And the face that had seemed so unnatural and inhuman was that way because it was, indeed, just that. It was a mask, designed to hide the little girl’s black skin. In short, Holmes’s wonderings have ended up far from the truth. How could the great detective have gone so wrong?

  Confidence in ourselves and in our skills allows us to push our limits and achieve more than we otherwise would, to try even those borderline cases where a less confident person would bow out. A bit of excess confidence doesn’t hurt; a little bit of above-average sensation can go a long way toward our psychological well-being and even our effectiveness at problem solving. When we’re more confident, we take on tougher problems than we otherwise might. We push ourselves beyond our comfort zone.

  But there can be such a thing as being too certain of yourself: overconfidence, when confidence trumps accuracy. We become more confident of our abilities, or of our abilities as compared with others’, than we should be, given the circumstances and the reality. The illusion of validity grows ever stronger, the temptation to do things as you do ever more tempting. This surplus of belief in ourselves can lead to unpleasant results—like being so incredibly wrong about a case when you are usually so incredibly right, thinking a daughter is a husband, or a loving mother, a blackmailed wife.

  It happens to the best of us. In fact, as I’ve hinted at already, it happens more to the best of us. Studies have shown that with experience, overconfidence increases instead of decreases. The more you know and the better you are in reality, the more likely you are to overestimate your own ability—and underestimate the force of events beyond your control. In one study, CEOs were shown to become more overconfident as they gained mergers and acquisitions experience: their estimates of a deal’s value become overly optimistic (something not seen in earlier deals). In another, in contributions to pension plans, overconfidence correlated with age and education, such that the most overconfident contributors were highly educated males nearing retirement. In research from the University of Vienna, individuals were found to be, in general, not overconfident in their risky asset trades in an experimental market—until, that is, they obtained significant experience with the market in question. Then levels of overconfidence rose apace. What’s more, analysts who have been more accurate at predicting earnings in the prior four quarters have been shown to be less accurate in subsequent earnings predictions, and professional traders tend to have a higher degree of overconfidence than students. In fact, one of the best predictors of overconfidence is power, which tends to come with time and experience.

  Success breeds overconfidence like nothing else. When we are nearly always right, how far is it to saying that we’ll always be right? Holmes has every reason to be confident. He is almost invariably correct, almost invariably better than anyone else at almost everything, be it thinking, solving crimes, playing the violin, or wrestling. And so, he should rightly fall victim to overconfidence often. His saving grace, however, or what is usually his saving grace, is precisely what we identified in the last section: that he knows the pitfalls of his mental stature and fights to avoid them by following his strict tho
ught guidelines, realizing that he needs to always keep learning.

  For those of us who live off the page, overconfidence remains a tricky thing. If we let our guard down for just a moment, as Holmes does here, it will get us.

  Overconfidence causes blindness, and blindness in turn causes blunders. We become so enamored of our own skill that we discredit information that experience would otherwise tell us shouldn’t be discredited—even information as glaring as Watson telling us that our theories are “all surmise,” as he does in this case—and we proceed as before. We are blinded for a moment to everything we know about not theorizing before the facts, not getting ahead of ourselves, prying deeper and observing more carefully, and we get carried away by the simplicity of our intuition.

  Overconfidence replaces dynamic, active investigation with passive assumptions about our ability or the seeming familiarity of our situation. It shifts our assessment of what leads to success from the conditional to the essential. I am skilled enough that I can beat the environment as easily as I have been doing. Everything is due to my ability, nothing due to the fact that the surroundings just so happened to provide a good background for my skill to shine. And so I will not adjust my behavior.

  Holmes fails to consider the possibility of unknown actors in the drama or unknown elements in Mrs. Munro’s biography. He also does not consider the possibility of disguise (something of a blind spot for the detective. If you remember, he, with equal confidence, does not take it into account in the case of Silver Blaze; nor does he do so in “The Man with the Twisted Lip”). Had Holmes had the same benefit of rereading his own exploits as we do, he may have learned that he was prone to this type of error.

  Many studies have shown this process in action. In one classic demonstration, clinical psychologists were asked to give confidence judgments on a personality profile. They were given a case report in four parts, based on an actual clinical case, and asked after each part to answer a series of questions about the patient’s personality, such as his behavioral patterns, interests, and typical reactions to life events. They were also asked to rate their confidence in their responses. With each section, background information about the case increased.

  As the psychologists learned more, their confidence rose—but accuracy remained at a plateau. Indeed, all but two of the clinicians became overconfident (in other words, their confidence outweighed their accuracy), and while the mean level of confidence rose from 33 percent at the first stage to 53 percent by the last, the accuracy hovered at under 28 percent (where 20 percent was chance, given the question setup).

  Overconfidence is often directly connected to this kind of underperformance—and at times, to grave errors in judgment. (Imagine a clinician in a nonexperimental setting trusting too much in his however inaccurate judgment. Is he likely to seek a second opinion or advise his patient to do so?) Overconfident individuals trust too much in their own ability, dismiss too easily the influences that they cannot control, and underestimate others—all of which leads to them doing much worse than they otherwise would, be it blundering in solving a crime or missing a diagnosis.

  The sequence can be observed over and over, even outside of experimental settings, when real money, careers, and personal outcomes are at stake. Overconfident traders have been shown to perform worse than their less confident peers. They trade more and suffer lower returns. Overconfident CEOs have been shown to overvalue their companies and delay IPOs, with negative effects. They are also more likely to conduct mergers in general, and unfavorable mergers in particular. Overconfident managers have been shown to hurt their firms’ returns. And overconfident detectives have been shown to blemish their otherwise pristine record through an excess of self-congratulation.

  Something about success has a tendency to bring about an end to that very essential process of constant, never-ending education—unless the tendency is actively resisted, and then resisted yet again. There’s nothing quite like victory to cause us to stop questioning and challenging ourselves in the way that is essential for Holmesian thinking.

  Learning to Spot the Signs of Overconfidence

  Perhaps the best remedy for overconfidence is knowing when it is most likely to strike. Holmes, for one, knows how liable past success and experience are to cause a blunder in thought. It is precisely this knowledge that lets him lay his master trap for the villain at the heart of the tragedies in The Hound of the Baskervilles. When the suspect learns that Sherlock Holmes has arrived at the scene, Watson worries that the knowledge will prove to make his capture all the more difficult: “I am sorry that he has seen you,” he tells Holmes. But Holmes is not so sure that it’s a bad thing. “And so was I at first,” he responds. But now he realizes that the knowledge, “may drive him to desperate measures at once. Like most clever criminals, he may be too confident in his own cleverness and imagine that he has completely deceived us.”

  Holmes knows that the successful criminal is likely to fall victim to his very success. He knows to watch out for the red flag of cleverness that thinks itself too clever, thereby underestimating its opponents while overestimating its own strength. And he uses that knowledge in his capture of the villain on multiple occasions—not just at Baskerville Hall.

  Spotting overconfidence, or the elements that lead to it, in others is one thing; identifying it in ourselves is something else entirely, and far more difficult. Hence Holmes’s Norbury blunders. Luckily for us, however, psychologists have made excellent headway in identifying where overconfidence most often lies in wait.

  Four sets of circumstances tend to predominate. First, overconfidence is most common when facing difficulty: for instance, when we have to make a judgment on a case where there’s no way of knowing all the facts. This is called the hard-easy effect. We tend to be underconfident on easy problems and overconfident on difficult ones. That means that we underestimate our ability to do well when all signs point to success, and we overestimate it when the signs become much less favorable, failing to adjust enough for the change in external circumstances. For instance, in something known as the choice-50 (C50) task, individuals must choose between two alternatives and then state how confident they are in their choice, between 0.5 and 1. Repeatedly, researchers have found that as the difficulty of the judgment increases, the mismatch between confidence and accuracy (i.e., overconfidence) increases dramatically.

  One domain where the hard-easy effect is prevalent is in the making of future predictions—a task that is nothing if not difficult (it is, as a matter of fact, impossible). The impossibility, however, doesn’t stop people from trying, and from becoming a bit too confident in their predictions based on their own perceptions and experience. Consider the stock market. It’s impossible to actually predict the movement of a particular stock. Sure, you might have experience and even expertise—but you are nevertheless trying to predict the future. Is it such a surprise, then, that the same people who at times have outsized success also have outsized failures? The more successful you are, the more likely you are to attribute everything to your ability—and not to the luck of the draw, which, in all future predictions, is an essential part of the equation. (It’s true of all gambling and betting, really, but the stock market makes it somewhat easier to think you have an inside, experiential edge.)

  Second, overconfidence increases with familiarity. If I’m doing something for the first time, I will likely be cautious. But if I do it many times over, I am increasingly likely to trust in my ability and become complacent, even if the landscape should change (overconfident drivers, anyone?). And when we are dealing with familiar tasks, we feel somehow safer, thinking that we don’t have the same need for caution as we would when trying something new or that we haven’t seen before. In a classic example, Ellen Langer found that people were more likely to succumb to the illusion of control (a side of overconfidence whereby you think you control the environment to a greater extent than you actually do) if they played a lottery that was familiar versus one that was unknown.


  It’s like the habit formation that we’ve been talking about. Each time we repeat something, we become better acquainted with it and our actions become more and more automatic, so we are less likely to put adequate thought or consideration into what we’re doing. Holmes isn’t likely to pull a Yellow Face-style mess-up on his early cases; it’s telling that the story takes place later in his career, and that it seems to resemble a more traditional blackmail case, the likes of which he has experienced many times before. And Holmes knows well the danger of familiarity, at least when it comes to others. In “The Adventure of the Veiled Lodger,” he describes the experience of a couple who had fed a lion for too long. “It was deposed at the inquest that there has been some signs that the lion was dangerous, but, as usual, familiarity begat contempt, and no notice was taken of the fact.” All Holmes has to do is apply that logic to himself.

  Third, overconfidence increases with information. If I know more about something, I am more likely to think I can handle it, even if the additional information doesn’t actually add to my knowledge in a significant way. This is the exact effect we observed earlier in the chapter with the clinicians who were making judgments on a case: the more information they had about the patient’s background, the more confident they were in the accuracy of the diagnosis, yet the less warranted was that confidence. As for Holmes, he has detail upon detail when he travels to Norbury But all the details are filtered through the viewpoint of Mr. Munro, who is himself unaware of the most important ones. And yet everything seems so incredibly plausible. Holmes’s theory certainly covers all of the facts—the known facts, that is. But Holmes doesn’t calibrate for the possibility that, despite the magnitude of the information, it continues to be selective information. He lets the sheer amount overwhelm what should be a note of caution: that he still knows nothing from the main actor who could provide the most meaningful information, Mrs. Munro. As ever, quantity does not equal quality.