Mastermind: How to Think Like Sherlock Holmes

by Maria Konnikova

  There it is a second time: smell. Holmes doesn’t just read the note and look at it. He also smells it. And in the scent, not in the words or the appearance, is where he finds the clue that helps him identify the possible criminal. Absent smell, two central clues of the case would remain unidentified—and so they do to everyone but the detective. I am not suggesting you go out and memorize seventy-five perfumes. But you should never neglect your sense of smell—or indeed any of your other senses—because they certainly won’t neglect you.

  Consider a scenario where you’re buying a car. You go to the dealer and look at all the shining specimens sitting out on the lot. How do you decide which model is the right one for you? If I ask you that question right now, you will likely tell me that you’d weigh any number of factors, from cost to safety, appearance to comfort, mileage to gas use. Then you’ll pick the vehicle that best matches your criteria.

  But the reality of the situation is far more complex. Imagine, for instance, that at the moment you’re in the lot, a man walks by with a mug of steaming hot chocolate. You might not even remember that he passed, but the smell triggers memories of your grandfather: he used to make you hot chocolate when you spent time together. It was your little ritual. And before you know it, you’re leaving the lot with a car like the one your grandfather drove—and have conveniently forgotten (or altogether failed to note) its less-than-stellar safety rating. And you very likely don’t even know why exactly you made the choice you did. You’re not wrong per se, but your selective remembering might mean a choice that you’ll later regret.

  Now imagine a different scenario. This time there’s a pervasive smell of gasoline: the lot is across the street from a gas station. And you remember your mother warning you to be careful around gas, that it could catch fire, that you could get hurt. Now you’re focused on safety. You’ll likely be leaving the lot with a car that is quite different from your grandfather’s. And again, you may not know why.

  Up to now, I’ve been talking about attention as a visual phenomenon. And it is, for the most part. But it is also much more. Remember how in the hypothetical foray to the top of the Empire State Building, our hypothetical Holmes listened and smelled for planes, as strange as it seemed? Attention is about every one of your senses: sight, smell, hearing, taste, touch. It is about taking in as much as we possibly can, through all of the avenues available to us. It is about learning not to leave anything out—anything, that is, that is relevant to the goals that you’ve set. And it is about realizing that all of our senses affect us—and will affect us whether or not we are aware of the impact.

  To observe fully, to be truly attentive, we must be inclusive and not let anything slide by—and we must learn how our attention may shift without our awareness, guided by a sense that we’d thought invisible. That jasmine? Holmes smelled the letter deliberately. In so doing, he was able to observe the presence of a female influence, and a particular female at that. If Watson had picked up the letter, we can be sure he would have done no such thing. But his nose may very well have grasped the scent even without his awareness. What then?

  When we smell, we remember. In fact, research has shown that the memories associated with smell are the most powerful, vivid, and emotional of all our recollections. And what we smell affects what we remember, how we subsequently feel, and what we might be inclined to think as a result. But smell is often referred to as the invisible sense: we regularly experience it without consciously registering it. A smell enters our nose, travels to our olfactory bulb, and makes its way directly to our hippocampus, our amygdala (an emotion-processing center), and our olfactory cortex (which not only deals with smells but is involved in complex memory, learning, and decision-making tasks), triggering a host of thoughts, feelings, and recollections—yet more likely than not, we note neither smell nor memory.

  What if Watson, in all of his multiple-continent-spanning womanizing, happened to have dated a woman who wore a jasmine perfume? Let’s imagine the relationship a happy one. All of a sudden he may have found himself seeing with added clarity (remember, happy moods equal wider sight), but he may also have failed to note select details because of a certain rosy glow to the whole thing. Maybe the letter isn’t so sinister. Maybe Henry isn’t in all that much danger. Maybe it would be better to go have a drink and meet some lovely ladies—after all, ladies are lovely, aren’t they? And off we go.

  And if the relationship had been violent, brutish, and short? Tunnel vision would have set in (bad mood, limited sight), and along with it a brushing aside of most of the elements of note. Why should that matter? Why should I work harder? I am tired; my senses are overloaded; and I deserve a break. And why is Henry bothering us anyway with this nonsense? Paranormal dog, my foot. I’ve about had it.

  When we are being inclusive, we never forget that all of our senses are constantly in play. We don’t let them drive our emotions and decisions. Instead, we actively enlist their help—as Holmes does with both boot and letter—and learn to control them instead.

  In either of the Watson scenarios above, all of the doctor’s actions, from the moment of smelling the jasmine, will have been affected. And while the precise direction of the effect is unknowable, one thing is certain. Not only would he have failed to be inclusive in his attention, but his attention will have been hijacked by the eponymous System Watson into a subjectivity that will be all the more limited for its unconscious nature.

  It may seem like I’m exaggerating, but I assure you, sensory influences—especially olfactory ones—are a powerful lot. And if we aren’t aware of them altogether, as so often happens, they can threaten to take over the carefully cultivated goals and objectivity that we’ve been working on.

  Smell may be the most glaring culprit, but it is far from alone. When we see a person, we are likely to experience the activation of any number of stereotypes associated with that person—though we won’t realize it. When we touch something warm or cold, we may become likewise warm or cold in our disposition; and if we are touched by someone in a reassuring way, we may suddenly find ourselves taking more risk or being more confident than we otherwise would. When we hold something heavy, we are more likely to judge something (or someone) to be weightier and more serious. None of this has anything to do with observation and attention per se, except that it can throw us off a carefully cultivated path without our awareness. And that is a dangerous thing indeed.

  We don’t have to be a Holmes and learn to tell apart hundreds of smells from a single whiff in order to let our senses work for us, to allow our awareness to give us a fuller picture of a scene that we would otherwise have. A scented note? You don’t need to know the smell to realize that it is there—and that it might be a potential clue. If you hadn’t paid attention to the fragrance, you would have missed the clue’s presence altogether—but you may have had your objectivity undermined nevertheless without even being aware of what has taken place. A missing boot? Another missing boot? Maybe it’s about a quality other than the boot’s appearance—after all, it’s the old and ugly one that eventually disappeared for good. You don’t need to know much to realize that there may be another sensory clue here that would again be missed if you had forgotten about your other senses. In both cases, a failure to use all senses equals a scene not seen to its full potential, attention that has not been allocated properly, and subconscious cues that color the attention that is allocated in a way that may not be optimal.

  If we actively engage each of our senses, we acknowledge that the world is multidimensional. Things are happening through our eyes, our nose, our ears, our skin. Each of those senses should rightly tell us something. And if it doesn’t, that should also tell us something: that a sense is missing. That something lacks smell, or is silent, or is otherwise absent. In other words, the conscious use of each sense can go beyond illuminating the present part of scene and show instead that part of a situation that is often forgotten: that which isn’t there, which is not present in the environment where by ev
ery rightful metric it should be. And absence can be just as important and just as telling as presence.

  Consider the case of Silver Blaze, that famous missing racehorse that no one can track down. When Holmes has had a chance to examine the premises, Inspector Gregson, who has failed to find something as seemingly impossible to miss as a horse, asks, “Is there any point to which you would wish to draw my attention?” Why yes, Holmes responds, “To the curious incident of the dog in the night-time.” But, protests the inspector, “The dog did nothing in the night-time.” To which Holmes delivers the punch line: “That was the curious incident.”

  For Holmes, the absence of barking is the turning point of the case: the dog must have known the intruder. Otherwise he would have made a fuss.

  For us, the absence of barking is something that is all too easy to forget. All too often, we don’t even dismiss things that aren’t there; we don’t remark on them to begin with—especially if the thing happens to be a sound, again a sense that is not as natural a part of attention and observation as sight. But often these missing elements are just as telling and just as important—and would make just as much difference to our thinking—as their present counterparts.

  We need not be dealing with a detective case for absent information to play an important role in our thought process. Take, for example, a decision to buy a cell phone. I’m going to show you two options, and I would like you to tell me which of them you would rather purchase.

  Phone A

  Phone B

  Wi-fi: 802.11 b/g

  802.11 b/g

  Talk time: 12 hrs

  16 hrs

  Standby time: 12.5 days

  14.5 days

  Memory: 16.0 GB

  32.0 GB

  Cost: $100

  $150

  Did you make a decision? Before you read on, jot down either Phone A or Phone B. Now I’m going to describe the phones one more time. No information has been changed, but some has been added.

  Phone A

  Phone B

  Wi-fi: 802.11 b/g

  802.11 b/g

  Talk time: 12 hrs

  16 hrs

  Standby time: 12.5 days

  14.5 days

  Memory: 16.0 GB

  32.0 GB

  Cost: $100

  $150

  Weight: 135g

  300g

  Which phone would you rather purchase now? Again, write down your answer. I’m now going to present the options a third time, again adding one new element.

  Phone A

  Phone B

  Wi-fi: 802.11 b/g

  802.11 b/g

  Talk time: 12 hrs

  16 hrs

  Standby time: 12.5 days

  14.5 days

  Memory: 16.0 GB

  32.0 GB

  Cost: $100

  $150

  Weight: 135g

  300g

  Radiation (SAR): 0.79 W/kg

  1.4 W/kg

  Now, which of the two would you prefer?

  Chances are, somewhere between the second and third lists of data, you switched your allegiance from Phone B to Phone A. And yet the two phones didn’t change in the least. All that did was the information that you were aware of. This is known as omission neglect. We fail to note what we do not perceive up front, and we fail to inquire further or to take the missing pieces into account as we make our decision. Some information is always available, but some is always silent—and it will remain silent unless we actively stir it up. And here I used only visual information. As we move from two to three dimensions, from a list to the real world, each sense comes into play and becomes fair game. The potential for neglecting the omitted increases correspondingly—but so does the potential for gleaning more about a situation, if we engage actively and strive for inclusion.

  Now let’s go back to that curious dog. He could have barked or not. He didn’t. One way to look at that is to say, as the inspector does, he did nothing at all. But another is to say, as Holmes does, that the dog actively chose not to bark. The result of the two lines of reasoning is identical: a silent dog. But the implications are diametrically opposed: passively doing nothing, or actively doing something.

  Nonchoices are choices, too. And they are very telling choices at that. Each nonaction denotes a parallel action; each nonchoice, a parallel choice; each absence, a presence. Take the well-known default effect: more often than not, we stick to default options and don’t expend the energy to change, even if another option is in fact better for us. We don’t choose to contribute to a retirement fund—even if our company will match the contributions—unless the default is set up for contributing. We don’t become organ donors unless we are by default considered donors. And the list goes on. It’s simply easier to do nothing. But that doesn’t mean we’ve actually not done anything. We have. We’ve chosen, in a way, to remain silent.

  To pay Attention means to pay attention to it all, to engage actively, to use all of our senses, to take in everything around us, including those things that don’t appear when they rightly should. It means asking questions and making sure we get answers. (Before I even go to buy that car or cell phone, I should ask: what are the features I care about most? And then I should be sure that I am paying attention to those features—and not to something else entirely.) It means realizing that the world is three-dimensional and multi-sensory and that, like it or not, we will be influenced by our environment, so our best bet is to take control of that influence by paying attention to everything that surrounds us. We may not be able to emerge with the entire situation in hand, and we may end up making a choice that, upon further reflection, is not the right one after all. But it won’t be for lack of trying. All we can do is observe to the best of our abilities and never assume anything, including that absence is the same as nothing.

  4. Be Engaged

  Even Sherlock Holmes makes the occasional mistake. But normally these are mistakes of misestimation—of a person, in the case of Irene Adler; a horse’s ability to stay hidden in “Silver Blaze”; a man’s ability to stay the same in “The Case of the Crooked Lip.” It is rare indeed that the mistake is a more fundamental one: a failure of engagement. Indeed, it is only on one occasion, as far as I’m aware, that the great detective is negligent in embodying that final element of attentiveness, an active, present interest and involvement, an engagement in what he is doing—and it almost costs him his suspect’s life.

  The incident takes place toward the end of “The Stock Broker’s Clerk.” In the story, the clerk of the title, Hall Pycroft, is offered a position as the business manager of the Franco-Midland Hardware Company by a certain Mr. Arthur Pinner. Pycroft has never heard of the firm and is slated to begin work the following week at a respected stockbrokerage—but the pay is simply too good to pass up. And so he agrees to begin work the next day. His suspicions are aroused, however, when his new employer, Mr. Pinner’s brother Harry, looks suspiciously like Mr. Arthur. What’s more, he finds that his so-called office employs no other man and doesn’t even have a sign on the wall to alert potential visitors of its existence. To top it off, Pycroft’s task is nothing like that of a clerk: he is to copy listings out of a thick phone book. When, a week later, he sees that Mr. Harry has the same gold tooth as did Mr. Arthur, he can stand the strangeness no more and so sets the problem before Sherlock Holmes.

  Holmes and Watson proceed to accompany Hall Pycroft to the Midlands, to the office of his employer. Holmes thinks he knows just what has gone on, and the plan is to visit the man on the pretense of looking for work, and then confront him as Holmes is wont to do. Every detail is in place. Every aspect of the situation is clear to the detective. It’s not like those cases where he actually needs the criminal to fill in major blanks. He knows what to expect. The only thing he requires is the man himself.

  But when the trio enters the offices, Mr. Pinner’s demeanor is not at all as expected. Watson describes the scene.

  At the single table sat the man who
m we had seen in the street, with his evening paper spread out in front of him, and as he looked up at us it seemed to me that I had never looked upon a face which bore such marks of grief, and of something beyond grief—of a horror such as comes to few men in a lifetime. His brow glistened with perspiration, his cheeks were of the dull, dead white of a fish’s belly, and his eyes were wild and staring. He looked at his clerk as though he failed to recognize him, and I could see by the astonishment depicted upon our conductor’s face that this was by no means the usual appearance of his employer.

  But what happens next is even more unexpected—and threatens to foil Holmes’s plans entirely. Mr. Pinner attempts to commit suicide.

  Holmes is at a loss. This he had not anticipated. Everything up to then is “clear enough, but what is not so clear is why at the sight of us the rogue should instantly walk out of the room and hang himself,” he says.

  The answer comes soon enough. The man is revived by the good Dr. Watson and provides it himself: the paper. He had been reading a newspaper—or rather, something quite specific in that paper, something that has caused him to lose his emotional equilibrium entirely—when he was interrupted by Sherlock and company. Holmes reacts to the news with uncharacteristic vigor. “‘The paper! Of course!’ yelled Holmes in a paroxysm of excitement. ‘Idiot that I was! I thought so much of our visit that the paper never entered my head for an instant.’”

  The moment the paper is mentioned, Holmes knows at once what it means and why it had the effect that it did. But why did he fail to note it in the first place, committing an error that even Watson would have hung his head in shame at making? How did the System Holmes machine become . . . a System Watson? Simple. Holmes says it himself: he had lost interest in the case. In his mind, it was already solved, down to the last detail—the visit, of which he thought so much that he decided it would be fine to disengage from everything else. And that’s a mistake he doesn’t normally make.