Sherlock Holmes and the Logic of Perception

Being Human 101: There is more to perception than meets the eye.

Posted Sep 25, 2020

Sir Arthur Conan Doyle often tells us in his stories about Sherlock Holmes and Dr. John H. Watson that his famous fictional detective is obsessive about attending to detail. As Sherlock cautions Watson in “A Case of Identity” first published in The Strand Magazine in September 1891: “Never trust to general impressions, my boy, but concentrate yourself upon details.”

 Unknown author / Wikimedia Commons, public domain
Source: Unknown author / Wikimedia Commons, public domain

I mentioned in one of my first posts in this series at Psychology Today that my son (and recent co-author) and I have come to see the human skull as being like a small yellow submarine with a crew of three inside. If you have been following this series, you know the three we have in mind are named Sherlock, George, and Alice.

However fictitious these three are, you also know we conjure them up to help us talk about what it means to think like a human being without suddenly finding ourselves lost in the forest of conflicting details and loosely connected facts that characterize much of psychology nowadays. 

In an earlier post, I connected the dots, so to speak, between Sherlock, George, and Alice, and what my son and I see as the three dimensions of human rationality encoded in the cryptic acronym PHI — Perception, Habit, and Imagination. Sherlock's obsessive awareness of the details of the world around him makes him a lively avatar for the first of these three dimensions, or characteristics, of human rationality — perception

But let's not overlook an important detail hiding inside the seemingly simple thought that there is something we can put our finger on that is called perception. When is a detail also a fact worth attending to? 

There's more to perception than meets the eye 

Gary Lupyan at the University of Wisconsin-Madison has explained it well. "Just as it is tempting to think of wind as a force passively captured by the sails, it is tempting to think of perception as passively capturing the information that surrounds us." This is good common sense, but poor science. Rather than being a passive cognitive process of accepting what the world gives us at face value, "perception is more accurately viewed as a constructive process of turning various forms of energy (mechanical, chemical, electromagnetic) into information useful for guiding behavior."

The important point Lupyan is making is a complex one. Said simply, what needs to be emphasized is that the brain plays an active, not a passive, role in "seeing," "hearing," "feeling," and so forth what is happening out there in the world.

Sherlock Holmes would agree with Lupyan. As he tells Dr. Watson repeatedly in Doyle's stories about their adventures together, what is essential to "those faculties of deduction and of logical synthesis which I have made my special province" is to observe, not just see.

What is Sherlock getting at here? As he tells us often enough in these stories, he has a turn both for observation and for deduction. 

And what does Sherlock mean by deduction? In a nutshell: the active search for meaningful patterns in the details being observed. Perhaps the most famous example in all of Doyle's stories about Holmes is what Sherlock explains to Watson and others in "The Adventure of Silver Blaise" (1892). Inspector Gregory from Scotland Yard asks Holmes: “Is there any point to which you would wish to draw my attention?”
          Holmes:   “To the curious incident of the dog in the nighttime.”
          Gregory:   “The dog did nothing in the night-time.”
          Holmes:   “That was the curious incident,” remarked Sherlock Holmes.

The logic of perception

Sherlock's popularity as a fictional character is as strong today as it was when Doyle was writing about him. Many have offered their take on what both Holmes and Doyle mean by the word "deduction." In A Study In Scarlet (1887), the novel in which these two famous sleuths make their first appearance, Sherlock patiently explains to Watson what he has in mind:

"Most people, if you describe a train of events to them, will tell you what the result would be. They can put those events together in their minds, and argue from them that something will come to pass. There are few people, however, who, if you told them a result, would be able to evolve from their own inner consciousness what the steps were which led up to that result. This power is what I mean when I talk of reasoning backwards, or analytically.”

Whether or not you accept Holmes' (and Doyle's) depiction of what it means to deduce something from what you have observed is not critical to the point I want to end with in this installment of Being Human 101.

Although he sees his uncommon sensitivity to the details of life as one of his peculiar powers, most of the time Holmes experiences the world as dull and boring. He so abhors the dull routine of daily life that he is willing to use artificial means such as alcohol and a 7% solution of cocaine to help him pass the time away between one exciting case and another.

Sherlock comes to mind, therefore, whenever I think of how the human brain works because he exemplifies not only how important it is for all of us to be critically observant of what is happening around us, but also how difficult it can be to stay genuinely engaged with what is happening in the world when what’s going on around us comes across as simply routine and drearily predictable.

Therefore, in this series at Psychology Today — as my son and I do also in our recently published book on understanding the human mind — I will be adopting Doyle’s Sherlock Holmes as my role model for the human brain’s contrary skillfulness at both (1) paying attention to what is happening in the world around it, but also (2) being altogether too prone to becoming bored when things become too predictable and routine. 

Next up – Being Human 101: Being Dull and Boring Isn't Necessarily Bad