More complicated subjects are far more difficult than pink elephants, of course. Consider the statement “There are no poisonous snakes in Maine.” It sounds plausible, and most of us would just let it go. (In fact, it is true.) This tendency, she tells us, is reinforced by what psychologists call the correspondence bias, by which we generally assume that what a person says is what he believes.

“Holmes’s trick is to treat every thought, every experience and every perception the way he would a pink elephant,” Ms. Konnikova writes. “In other words, begin with a healthy dose of skepticism instead of the credulity that is your mind’s natural state of being.” This requires mindfulness — constant presence of mind, “the attentiveness and hereness that is so essential for real active observation of the world.” If we want to think like Sherlock Holmes, “we must want, actively, to think like him.” And practice, practice, practice.

We also have to learn to ignore the superfluous. Holmes famously claimed ignorance of the solar system: “What the deuce is it to me?” he says in “A Study in Scarlet.” “I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose.” A skillful worker “is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work.”

Of course Holmes has a great deal in his brain-attic, even if it does not include the solar system. On first meeting Dr. John H. Watson, for example, he runs through a split-second inventory of social, political and geographical facts and announces, “You have been in Afghanistan, I perceive.” Watson is astonished, and soon the two are inseparable.