6.4 A World of Differences

“Some minds are stronger and apter to mark the differences of things, others to mark their resemblances. The steady and acute mind can fix its contemplations and dwell and fasten on the subtlest distinctions: the lofty and discursive mind recognizes and puts together the finest and most general resemblances. Both kinds however easily err in excess, by catching the one at gradations, the other at shadows.” —Francis Bacon, Novum Organum, 1620.

Whenever somebody tells you a story, you react less to what each separate sentence means than to how this differs from what you expected—and this also applies to our other perceptions. For example, if you plunge your hand into a bowl of cold water, you'll feel a severe sensation of chill—but soon this will totally disappear, just as a steady pressure on your skin will quickly seem to diminish in strength. It is the same with new odors or tastes, or with the onsets of continuous sounds: at first those sensations may seem intense but then they rapidly fade away. We have many different names for this, like accommodation, adaptation, acclimatization, habituation, or just becoming accustomed to it.

Student: This doesn’t apply to vision, though. I can look at an object as long as I like, and its image never fades; in fact, I keep seeing more features of it.

Physiologist: In fact, that image would rapidly fade if you could keep from moving your eyes, which normally make small motions that keep changing your retinal images.[24]

Thus most of our external sensors react only to rather rapid changes in conditions. However, we also have additional sensors that do not fade away, but keep responding to certain particular harmful conditions; see §§Alarms.

Now let’s apply the same idea—of a system that ‘mainly reacts to change’— to a brain with a tower of cognitive levels. This could help to explain some phenomena. For example, after you start a trip on a train, you’re aware of the clacking of wheels on the track—but (if that clacking is regular) then you will soon stop noticing this. Perhaps your A-Brain is still processing it, but your B-brain has stopped reacting to it. It will be much the same for the visual scenes; when the train enters a forest, you’ll start seeing trees—but soon you’ll start to ignore them. What could cause such meanings to fade?

It’s much the same with repeated words; if someone says ‘rabbit’ one hundred times, while trying to focus on what that word means, then that meaning will shortly disappear—or be replaced by some other one. And similarly the same thing happens when you listen to popular music: you’ll often hear dozens of nearly identical measures, but the details of these soon fade away and you no longer pay any attention to them. Why don’t we object to that repetitiousness?

This could be partly because we tend to interpret such ‘narratives’ in terms of how situations change on successively larger scales of time. In the case of most music, this structure is clear: we begin by grouping separate notes into ‘measures’ of equal length, and we then group these into larger sections, until the whole composition is seen as a storylike structure. [25] We do this in vision and language, too—although with less repetitiousness— by grouping collections of smaller events into multiple levels of events, incidents, episodes, sections, and plots. However, we see most clearly in musical forms:

Feature-Detectors recognize pauses, notes, and various other aspects of sounds, such as harmony, tempo, and timbre, etc.

Measure-Takers group these into chunks. In music, composers make this easy for us by using measures of equal length; this makes it extremely easy to sense the differences between successive chunks.

Phrase- and Theme-Detectors then represent larger events and relationships like, ‘This theme goes down and then goes up, and ends with three short, separate notes.’

Then Section-Builders group these into larger-scale parts, such as, ‘these three similar episodes form a sequence that rises in pitch.’ [26]

Finally, our Storytellers interpret these as similar to events in other realms—such as depicting a journey through space and time, or a skirmish among personalities. One special appeal of music is how effectively it can depict what we might call abstract emotional scripts—stories that seem to be about entities about whom we know nothing at all except that we can recognize their individual characteristics—e.g., this one is warm and affectionate, whereas that one is cold and insensitive. Then we empathize with how they feel as we interpret those phrases and themes as representing mental conditions like conflict, adventure, surprise, and dismay—as in, those horns are attacking the clarinets, but the strings are now trying to calm them down.

Now suppose that each higher level in the brain mainly reacts to the changes below it, but over some larger scale of time. If so, then when signals repeat at level A, the B-Brain will have nothing to say. And if the signals that go up to B form a sequence that repeats—so that the B-brain keeps seeing a similar pattern—then the C-Brain will sense a ‘constant condition,’ and thus have nothing to say to the level above it.

This could explain some common experiences because any repetitive signal would tend to partly ‘anesthetize’ the next level above it. So although your foot may continue to tap, most details of those smaller events won’t go up.

(Why might our brains have evolved to work this way? If some condition has been present for long—and nothing bad has happened to you—then it probably poses no danger to you; then so you might as well not pay attention to it and apply your resources more gainfully.)

However, this could also lead to other effects. Once a level gets freed from control by repetitive signals that come from below it, then it could start to send signals down to instruct those levels to try to detect different kinds of evidence. For example, during that railroad trip, perhaps you first heard those clacks on the tracks as forming a pattern of clack-clack-clack-clacks—that is, of beats in 4:4 time. Then you stopped hearing them at all—but soon you may have suddenly switched to hearing groups of ‘clack-clack-clacks’—that is, of beats in 3:4 time. What made you change your representation? Perhaps some higher level just switched to forming a different hypothesis.

Also, when repetitive signals anesthetize some parts of your brain, this could release some other resources to think in new, unusual ways. This could be why some types of meditation can thrive on repetitive mantras and chants. It also could contribute to what making some music so popular: by depriving the listener of some usual inputs, that repetitiousness could free higher-level systems to pursue their own ideas. Then, as suggested in §5-8, they could send down some ‘simuli’ to make some lower level resources simulate some imaginary fantasies.

Rhythmic and Musical Differences

“Music can move us through brief emotional states, and this can potentially teach us how to manage our feelings by giving us familiarity to transitions between the states that we know and thus gain greater confidence in handling them.” —Matthew McCauley

Music (or art, or rhetoric) can divert you from your mundane concerns by evoking powerful feelings that range from delight and pleasure to sorrow and pain; these can excite your ambitions and stir you to act, or calm you down and make you relax, or even put you into a trance. To do this, those signals must suppress or enhance various sets of mental resources—but why should those kinds of stimuli have such effects on your feeling and thinking?

We all know that certain temporal patterns can lead to rather specific mental states; a jerky motion or crashing sound arouses a sense of panic and fear—whereas a smoothly changing phrase or touch induces affection or peacefulness. [27] Some such reactions could be wired from birth—for example, to facilitate relationships between infants and parents. For then, each party will have some control over what the other one feels, thinks, and does.

Subsequently, as we grow up, we each learn similar ways to control ourselves! We can do this by listening to music and songs, or by exploiting other external things, such as drugs, entertainment, or changes of scene. Then we also discover techniques for affecting our mental states ‘from inside’—for example, by thinking that music inside our minds. (This can have a negative side, as when you hear a person complain that they can’t get a certain tune out of their head.)

Eventually, for each of us, certain sights and sounds come to have more definite significances—as when bugles and drums depict battles and guns. However, we usually each have different ideas about what each fragment of music means—particularly when it reminds us of how we felt during some prior experience. This has led some thinkers to believe that music expresses those feelings themselves, whereas those effects are probably far less direct:

G. Spencer Brown: “[In musical works] the composer does not even attempt to describe the set of feelings occasioned through them, but writes down a set of commands which, if they are obeyed by the reader, can result in a reproduction, to the reader, of the composer's original experience. [28]”

However, some other thinkers would disagree:

• Marcel Proust: "Each reader reads only what is already inside himself. A book is only a sort of optical instrument which the writer offers to let the reader discover in himself what he would not have found without the aid of the book."

Perhaps Felix Mendelssohn had something like this in mind when he said, “the meaning of music lies not in the fact that it is too vague for words, but that it is too precise for words.”

All of this raises questions that people seem strangely reluctant to ask—such why do so many people like music so much, and permit it to take up so much of their lives.[29] In particular, we ought to ask why nursery rhymes and lullabies occur in so many cultures and societies. In Music, Mind, and Meaning I suggested some possible reasons for this: perhaps we use those tidy structures of notes and tunes as simplified ‘virtual’ worlds for refining difference-detectors that we can then use for condensing more complex events (in other realms) into more orderly story-like scripts. See also §§Interior grounding.

Difference-Networks

Whenever you want to accomplish some purpose, you will need to decide which things to change. To do this you’ll need to retrieve some knowledge about which actions that might help make those changes. But what should you do when what you have does not exactly match what you need? Then you’ll want to find some substitute that is different—but not too dissimilar.

Whenever you want to accomplish some goal, you will need to retrieve some knowledge about some actions or objects that might help. For example, suppose that you want to sit down, so you look for a chair, but none is in sight. However, if there were a bench in view, then you might regard it as suitable. What leads you to see the bench as similar—when you would not so regard a book or a lamp? What makes us selectively notice things that are likely to be relevant? Patrick Winston suggested doing this by organizing some bodies of knowledge into what he called "difference networks"—for example, like this:[30]

To use such a structure, one first must have some descriptions of the objects it represents. Thus a typical concept of a chair might involve four legs, a level seat, and a vertical back, in which the legs must support the seat from below at a proper height above the floor—whereas a bench is similar (except for being wider and not having a back).

Now, when you look for a thing that matches your description of ‘chair,’ your furniture-network could recognize a bench as similar. Then you can choose to accept that bench, or reject it because it is too wide or has no back.

How might we accumulate useful sets of difference-links? One way would be that, whenever we find an A that ‘almost works’ (that is, for our present purposes) along with a B that actually works, we connect the two with a difference-link that represents, “A is like B, except for a difference D.” Then such networks could also embody the knowledge we need to change what we have into what we need—as well as to suggest alternative views whenever the present one fails. Thus, such difference-networks could help us to retrieve memories that are relevant.

Traditional programs did not take this approach, but were designed to use more ‘logical’ schemes—such as regarding a chair as an instance of furniture, and a table as one kind of furniture. Such hierarchical classifications often help to find suitably similar things, but they also can make many kinds of mistakes. I suspect that people use both techniques but that the ‘sideways’ connections in our difference-networks are vital to how we construct the analogies that are among our most useful ways to think.