Mastermind: How to Think Like Sherlock Holmes

by Maria Konnikova

  Why does Holmes note the details he does in Watson’s appearance—and why did his real-life counterpart Bell choose to observe what he did in the demeanor of his new patient? (“You see gentlemen,” the surgeon told his students, “the man was a respectful man but did not remove his hat. They do not in the army, but he would have learned civilian ways had he been long discharged. He had an air of authority,” he continued, “and is obviously Scottish. As to Barbados, his complaint is elephantiasis, which is West Indian and not British, and the Scottish regiments are at present in that particular land.” And how did he know which of the many details of the patient’s physical appearance were important? That came from sheer practice, over many days and years. Dr. Bell had seen so many patients, heard so many life stories, made so many diagnoses that at some point, it all became natural—just as it did for Holmes. A young, inexperienced Bell would have hardly been capable of the same perspicacity.)

  Holmes’s explanation is preceded by the two men’s discussion of the article “The Book of Life” that Holmes had written for the morning paper—the same article I referred to earlier, which explains how the possibility of an Atlantic or a Niagara could emerge from a single drop of water. After that aqueous start, Holmes proceeds to expand the principle to human interaction.

  Before turning to those moral and mental aspects of the matter which present the greatest difficulties, let the inquirer begin by mastering more elementary problems. Let him, on meeting a fellow-mortal, learn at a glance to distinguish the history of the man, and the trade or profession to which he belongs. Puerile as such an exercise may seem, it sharpens the faculties of observation, and teaches one where to look and what to look for. By a man’s finger-nails, by his coat-sleeve, by his boots, by his trouser-knees, by the callosities of his forefinger and thumb, by his expression, by his shirt-cuffs—by each of these things a man’s calling is plainly revealed. That all united should fail to enlighten the competent inquirer in any case is almost inconceivable.

  Let’s consider again how Holmes approaches Watson’s stint in Afghanistan. When he lists the elements that allowed him to pinpoint the location of Watson’s sojourn, he mentions, in one example of many, a tan in London—something that is clearly not representative of that climate and so must have been acquired elsewhere—as illustrating his having arrived from a tropical location. His face, however, is haggard. Clearly then, not a vacation, but something that made him unwell. And his bearing? An unnatural stiffness in one arm, such a stiffness as could result from an injury.

  Tropics, sickness, injury: take them together, as pieces of a greater picture, and voilà. Afghanistan. Each observation is taken in context and in tandem with the others—not just as a stand-alone piece but as something that contributes to an integral whole. Holmes doesn’t just observe. As he looks, he asks the right questions about those observations, the questions that will allow him to put it all together, to deduce that ocean from the water drop. He need not have known about Afghanistan per se to know that Watson came from a war; he may not have known what to call it then, but he could have well come up with something along the lines of, “You have just come from the war, I perceive.” Not as impressive sounding, to be sure, but having the same intent.

  As for profession: the category doctor precedes military doctor—category before subcategory, never the other way around. And about that doctor: quite a prosaic guess at a man’s profession for someone who spends his life dealing with the spectacular. But prosaic doesn’t mean wrong. As you’ll note if you read Holmes’s other explanations, rarely do his guesses of professions jump—unless with good reason—into the esoteric, sticking instead to more common elements—and ones that are firmly grounded in observation and fact, not based on overheard information or conjecture. A doctor is clearly a much more common profession than, say, a detective, and Holmes would never forget that. Each observation must be integrated into an existing knowledge base. In fact, were Holmes to meet himself, he would categorically not guess his own profession. After all, he is the self-acknowledged only “consulting detective” in the world. Base rates—or the frequency of something in a general population—matter when it comes to asking the right questions.

  For now, we have Watson, the doctor from Afghanistan. As the good doctor himself says, it’s all quite simple once you see the elements that led to the conclusion. But how do we learn to get to that conclusion on our own?

  It all comes down to a single word: attention.

  Paying Attention Is Anything but Elementary

  When Holmes and Watson first meet, Holmes at once correctly deduces Watson’s history. But what of Watson’s impressions? First, we know he pays little attention to the hospital—where he is heading to meet Holmes for the first time—as he enters it. “It was familiar ground,” he tells us, and he needs “no guiding.”

  When he reaches the lab, there is Holmes himself. Watson’s first impression is shock at his strength. Holmes grips his hand “with a strength for which [Watson] should hardly have given him credit.” His second is surprise at Holmes’s interest in the chemical test that he demonstrates for the newcomers. His third, the first actual observation of Holmes physically: “I noticed that [his hand] was all mottled over with similar pieces of plaster, and discoloured with strong acids.” The first two are impressions—or preimpressions—more than observations, much closer to the instinctive, preconscious judgment of Joe Stranger or Mary Morstan in the prior chapter. (Why shouldn’t Holmes be strong? It seems that Watson has jumped the gun by assuming him to be somehow akin to a medical student, and thus someone who is not associated with great physical feats. Why shouldn’t Holmes be excited? Again, Watson has already imputed his own views of what does and does not qualify as interesting onto his new acquaintance.) The third is an observation in line with Holmes’s own remarks on Watson, the observations that lead him to his deduction of service in Afghanistan—except that Watson only makes it because Holmes draws his attention to it by putting a Band-Aid on his finger and remarking on that very fact. “I have to be careful,” he explains. “I dabble with poisons a good deal.” The only real observation, as it turns out, is one that Watson doesn’t actually make until it is pointed out to him.

  Why the lack of awareness, the superficial and highly subjective assessment? Watson answers for us when he enumerates his flaws to Holmes—after all, shouldn’t prospective flatmates know the worst about each other? “I am extremely lazy,” he says. In four words, the essence of the entire problem. As it happens, Watson is far from alone. That fault bedevils most of us—at least when it comes to paying attention. In 1540, Hans Ladenspelder, a copperplate engraver, finished work on an engraving that was meant to be part of a series of seven: a female, reclining on one elbow on a pillar, her eyes closed, her head resting on her left hand. Peeking out over her right shoulder, a donkey. The engraving’s title: “Acedia.” The series: The Seven Deadly Sins.

  Acedia means, literally, not caring. Sloth. A laziness of the mind that the Oxford Dictionary defines as “spiritual or mental sloth; apathy.” It’s what the Benedictines called the noonday demon, that spirit of lethargy that tempted many a devoted monk to hours of idleness where there should have rightly been spiritual labor. And it’s what today might pass for attention deficit disorder, easy distractibility, low blood sugar, or whatever label we choose to put on that nagging inability to focus on what we need to get done.

  Whether you think of it as a sin, a temptation, a lazy habit of mind, or a medical condition, the phenomenon begs the same question: why is it so damn hard to pay attention?

  It’s not necessarily our fault. As neurologist Marcus Raichle learned after decades of looking at the brain, our minds are wired to wander. Wandering is their default. Whenever our thoughts are suspended between specific, discrete, goal-directed activities, the brain reverts to a so-called baseline, “resting” state—but don’t let the word fool you, because the brain isn’t at rest at all. Instead, it experiences tonic activity in what’s
now known as the DMN, the default mode network: the posterior cingulate cortex, the adjacent precuneus, and the medial prefrontal cortex. This baseline activation suggests that the brain is constantly gathering information from both the external world and our internal states, and what’s more, that it is monitoring that information for signs of something that is worth its attention. And while such a state of readiness could be useful from an evolutionary standpoint, allowing us to detect potential predators, to think abstractly and make future plans, it also signifies something else: our minds are made to wander. That is their resting state. Anything more requires an act of conscious will.

  The modern emphasis on multitasking plays into our natural tendencies quite well, often in frustrating ways. Every new input, every new demand that we place on our attention is like a possible predator: Oooh, says the brain. Maybe I should pay attention to that instead. And then along comes something else. We can feed our mind wandering ad infinitum. The result? We pay attention to everything and nothing as a matter of course. While our minds might be made to wander, they are not made to switch activities at anything approaching the speed of modern demands. We were supposed to remain ever ready to engage, but not to engage with multiple things at once, or even in rapid succession.

  Notice once more how Watson pays attention—or not, as the case may be—when he first meets Holmes. It’s not that he doesn’t see anything. He notes “countless bottles. Broad, low tables were scattered about, which bristled with retorts, test-tubes, and little Bunsen lamps, with their blue flickering flames.” All that detail, but nothing that makes a difference to the task at hand—his choice of future flatmate.

  Attention is a limited resource. Paying attention to one thing necessarily comes at the expense of another. Letting your eyes get too taken in by all of the scientific equipment in the laboratory prevents you from noticing anything of significance about the man in that same room. We cannot allocate our attention to multiple things at once and expect it to function at the same level as it would were we to focus on just one activity. Two tasks cannot possibly be in the attentional foreground at the same time. One will inevitably end up being the focus, and the other—or others—more akin to irrelevant noise, something to be filtered out. Or worse still, none will have the focus and all will be, albeit slightly clearer, noise, but degrees of noise all the same.

  Think of it this way. I am going to present you with a series of sentences. For each sentence, I want you to do two things: one, tell me if it is plausible or not by writing a P for plausible or a N for not plausible by the sentence; and two, memorize the final word of the sentence (at the end of all of the sentences, you will need to state the words in order). You can take no more than five seconds per sentence, which includes reading the sentence, deciding if it’s plausible or not, and memorizing the final word. (You can set a timer that beeps at every five-second interval, or find one online—or try to approximate as best you can.) Looking back at a sentence you’ve already completed is cheating. Imagine that each sentence vanishes once you’ve read it. Ready?

  She was worried about being too hot so she took her new shawl.

  She drove along the bumpy road with a view to the sea.

  When we add on to our house, we will build a wooden duck.

  The workers knew he was not happy when they saw his smile.

  The place is such a maze it is hard to find the right hall.

  The little girl looked at her toys then played with her doll.

  Now please write down the final word of each sentence in order. Again, do not try to cheat by referring back to the sentences.

  Done? You’ve just completed a sentence-verification and span task. How did you do? Fairly well at first, I’m guessing—but it may not have been quite as simple as you’d thought it would be. The mandatory time limit can make it tricky, as can the need to not only read but understand each sentence so that you can verify it: instead of focusing on the last word, you have to process the meaning of the sentence as a whole as well. The more sentences there are, the more complex they become, the trickier it is to tell if they are plausible or not, and the less time I give you per sentence, the less likely you are to be able to keep the words in mind, especially if you don’t have enough time to rehearse.

  However many words you can manage to recall, I can tell you several things. First, if I were to have you look at each sentence on a computer screen—especially at those times when it was the most difficult for you (i.e., when the sentences were more complex or when you were nearing the end of a list), so that you were keeping more final words in mind at the same time—you would have very likely missed any other letters or images that may have flashed on the screen while you were counting: your eyes would have looked directly at them, and yet your brain would have been so preoccupied with reading, processing, and memorizing in a steady pattern that you would have failed to grasp them entirely. And your brain would have been right to ignore them—it would have distracted you too much to take active note, especially when you were in the middle of your given task.

  Consider the policeman in A Study in Scarlet who misses the criminal because he’s too busy looking at the activity in the house. When Holmes asks him whether the street was empty, Rance (the policeman in question) says, “Well, it was, as far as anybody that could be of any good goes.” And yet the criminal was right in front of his eyes. Only, he didn’t know how to look. Instead of a suspect, he saw a drunk man—and failed to note any incongruities or coincidences that might have told him otherwise, so busy was he trying to focus on his “real” job of looking at the crime scene.

  The phenomenon is often termed attentional blindness, a process whereby a focus on one element in a scene causes other elements to disappear; I myself like to call it attentive inattention. The concept was pioneered by Ulric Neisser, the father of cognitive psychology. Neisser noticed how he could look out a window at twilight and either see the external world or focus on the reflection of the room in the glass. But he couldn’t actively pay attention to both. Twilight or reflection had to give. He termed the concept selective looking.

  Later, in the laboratory, he observed that individuals who watched two superimposed videos in which people engaged in distinct activities—for instance, in one video they were playing cards, and in the other, basketball—could easily follow the action in either of the films but would miss entirely any surprising event that happened in the other. If, for example, they were watching the basketball game, they would not notice if the cardplayers suddenly stopped playing cards and instead stood up to shake hands. It was just like selective listening—a phenomenon discovered in the 1950s, in which people listening to a conversation with one ear would miss entirely something that was said in their other ear—except, on an apparently much broader scale, since it now applied to multiple senses, not just to a single one. And ever since that initial discovery, it has been demonstrated over and over, with visuals as egregious as people in gorilla suits, clowns on unicycles, and even, in a real-life case, a dead deer in the road escaping altogether the notice of people who were staring directly at them.

  Scary, isn’t it? It should be. We are capable of wiping out entire chunks of our visual field without knowingly doing so. Holmes admonished Watson for seeing but not observing. He could have gone a step further: sometimes we don’t even see.

  We don’t even need to be actively engaged in a cognitively demanding task to let the world pass us by without so much as a realization of what we’re missing. For instance, when we are in a foul mood, we quite literally see less than when we are happy. Our visual cortex actually takes in less information from the outside world. We could look at the exact same scene twice, once on a day that has been going well and once on a day that hasn’t, and we would notice less—and our brains would take in less—on the gloomy day.

  We can’t actually be aware unless we pay attention. No exceptions. Yes, awareness may require only minimal attention, but it does require some attention. Nothing happe
ns quite automatically. We can’t be aware of something if we don’t attend to it.

  Let’s go back to the sentence-verification task for a moment. Not only will you have missed the proverbial twilight for focusing too intently at the reflection in the window, but the harder you were thinking, the more dilated your pupils will have become. I could probably tell your mental effort—as well as your memory load, your ease with the task, your rate of calculation, and even the neural activity of your locus coeruleus (the only source in the brain of the neurotransmitter norepinephrine and an area implicated in memory retrieval, a variety of anxiety syndromes, and selective attentional processing), which will also tell me whether you are likely to keep going or to give up—just by looking at the size of your pupils.

  But there is one encouraging thing: the importance—and effectiveness—of training, of brute practice, is overwhelmingly clear. If you were to do the sentence verification regularly—as some subjects did in fact do—your pupils would gradually get smaller; your recall would get more natural; and, miracle of all miracles, you’d notice those same letters or images or whatnot that you’d missed before. You’d probably even ask yourself, how in the world did I not see this earlier? What was previously taxing will have become more natural, more habitual, more effortless; in other words, easier. What used to be the purview of the Holmes system would have sneaked into the Watson system. And all it will have taken is a little bit of practice, a small dose of habit formation. Your brain can be one quick study if it wants to be.

  The trick is to duplicate that same process, to let your brain study and learn and make effortless what was once effortful, in something that lacks the discrete nature of a cognitive task like the sentence verification, in something that is so basic that we do it constantly, without giving it much thought or attention: the task of looking and thinking.