I will later discuss the issue of consciousness and make the point that we tend to equate consciousness with our memory of events. The primary reason we believe that we are not conscious when under anesthesia is that we don’t remember anything from that period (albeit there are intriguing—and disturbing—exceptions to this). So with regard to the walk I took this morning, was I not conscious during most of it? It’s a reasonable question, given that I remember almost nothing about what I saw or even what I was thinking about.
There happen to be a few things I do remember from my walk this morning. I recall thinking about this book, but I couldn’t tell you exactly what those thoughts were. I also recall passing a woman pushing a baby carriage. I remember that the woman was attractive, and that the baby was cute as well. I recall two thoughts I had in connection with this experience: This baby is adorable, like my new grandson, and What is this baby perceiving in her visual surroundings? I cannot recall what either of them was wearing or the color of their hair. (My wife will tell you that that is typical.) Although I am unable to describe anything specific about their appearance, I do have some ineffable sense of what the mom looked like and believe I could pick out her picture from among those of several different women. So while there must be something about her appearance that I have retained in my memory, if I think about the woman, baby carriage, and baby, I am unable to visualize them. There is no photograph or video of this event in my mind. It is hard to describe exactly what is in my mind about this experience.
I also recall having passed a different woman with a baby carriage on a walk a few weeks earlier. In that case I don’t believe I could even recognize that woman’s picture. That memory is now much dimmer than it must have been shortly after that walk.
Next, think about people whom you have encountered only once or twice. Can you visualize them clearly? If you are a visual artist, then you may have learned this observational skill, but typically we are unable to visualize people we’ve only casually come across to draw or describe them sufficiently but would have little difficulty in recognizing a picture of them.
This suggests that there are no images, videos, or sound recordings stored in the brain. Our memories are stored as sequences of patterns. Memories that are not accessed dim over time. When police sketch artists interview a crime victim, they do not ask, “What did the perpetrator’s eyebrows look like?” Rather, they will show a series of images of eyebrows and ask the victim to select one. The correct set of eyebrows will trigger the recognition of the same pattern that is stored in the victim’s memory.
Let’s now consider faces that you know well. Can you recognize any of these people?
You are undoubtedly able to recognize these familiar personalities, even though they are partially covered or distorted. This represents a key strength of human perception: We can recognize a pattern even if only part of it is perceived (seen, heard, felt) and even if it contains alterations. Our recognition ability is apparently able to detect invariant features of a pattern—characteristics that survive real-world variations. The apparent distortions in a caricature or in certain forms of art such as impressionism emphasize the patterns of an image (person, object) that we recognize while changing other details. The world of art is actually ahead of the world of science in appreciating the power of the human perceptual system. We use the same approach when we recognize a melody from only a few notes.
Now consider this image:
The image is ambiguous—the corner indicated by the black region may be an inside corner or an outside corner. At first you are likely to perceive it one way or the other, though with some effort you can change your perception to the alternate interpretation. Once your mind has fixed on an understanding, however, it may be difficult to see the other perspective. (This turns out to be true of intellectual perspectives as well.) Your brain’s interpretation of the image actually influences your experience of it. When the corner appears to be an inside one, your brain will interpret the grey region as a shadow, so it does not seem to be as dark as when you interpret the corner as being an outside one.
Thus our conscious experience of our perceptions is actually changed by our interpretations.
Consider that we see what we expect to ___
I’m confident that you were able to complete the above sentence.
Had I written out the last word, you would have needed only to glance at it momentarily to confirm that it was what you had expected.
This implies that we are constantly predicting the future and hypothesizing what we will experience. This expectation influences what we actually perceive. Predicting the future is actually the primary reason that we have a brain.
Consider an experience that we all have on a regular basis: A memory from years ago inexplicably pops into your head.
Often this will be a memory of a person or an event that you haven’t thought about for a long time. It is evident that something has triggered the memory. The train of thought that did so may be apparent and something you are able to articulate. At other times you may be aware of the sequence of thoughts that led to the memory but would have a hard time expressing it. Often the trigger is quickly lost, so the memory appears to have come from nowhere. I often experience these random memories while doing routine procedures such as brushing my teeth. Sometimes I may be aware of the connection—the toothpaste falling off the toothbrush might remind me of the paint falling off a brush in a painting class I took in college. Sometimes I have only a vague sense of the connection, or none at all.
A related phenomenon that everyone experiences frequently is trying to think of a name or a word. The procedure we use in this circumstance is to try to remind ourselves of triggers that may unlock the memory. (For example: Who played Queen Padmé in Revenge of the Sith? Let’s see, it’s that same actress who was the star in a recent dark movie about dancing, that was Black Swan, oh yes, Natalie Portman.) Sometimes we adopt idiosyncratic mnemonics to help us remember. (For example: She’s always slim, not portly, oh yes, Portman, Natalie Portman.) Some of our memories are sufficiently robust that we can go directly from a question (such as who played Queen Padmé) to the answer; often we need to go through a series of triggers until we find one that works. It’s very much like having the right Web link. Memories can indeed become lost like a Web page to which no other page links to (at least no page that we can find).
While executing routine procedures—such as putting on a shirt—watch yourself performing them, and consider the extent to which you follow the same sequence of steps each time. From my own observation (and as I mentioned, I am constantly trying to observe myself), it is likely that you follow very much the same steps each time you perform a particular routine task, though there may be additional modules added. For example, most of my shirts do not require cuff links, but when one does, that involves a further series of tasks.
The lists of steps in my mind are organized in hierarchies. I follow a routine procedure before going to sleep. The first step is to brush my teeth. But this action is in turn broken into a smaller series of steps, the first of which is to put toothpaste on the toothbrush. That step in turn is made up of yet smaller steps, such as finding the toothpaste, removing the cap, and so on. The step of finding the toothpaste also has steps, the first of which is to open the bathroom cabinet. That step in turn requires steps, the first of which is to grab the outside of the cabinet door. This nesting actually continues down to a very fine grain of movements, so that there are literally thousands of little actions constituting my nighttime routine. Although I may have difficulty remembering details of a walk I took just a few hours ago, I have no difficulty recalling all of these many steps in preparing for bed—so much so that I am able to think about other things while I go through these procedures. It is important to point out that this list is not stored as one long list of thousands of steps—rather, each of our routine procedures is remembered as an elaborate hierarchy of nested activities.