A full orchestra is playing, with the stringed instruments in front.

Interpersonal Synchrony

When we’re with other people, we tend to act as they do, and they act as we do. We synchronize, in walking, singing, alerting to danger, violin playing (research here), and many other kinds of behavior. We’re not unique in this, but the extent of it can be surprising because we rarely label it the way we do schooling of fish, swarming of bees, or the flocking of geese.

Our synchrony usually doesn’t arise from the motive we ascribe to other animals, defense against predators, but it conforms to many of the same constraints: sharing a common environment, similar body structure, and even common brain mechanisms.

And even if the threats we face aren’t overwhelmed by a show of grouping and imitation—consider infectious viruses and automobile traffic—we are often well served by synchronized behavior. Our other behavior tends to improve, for example (discussed more there), even if we sacrifice some independent regulation and must endure the stigma attached to “following the crowd”. There are exceptions, discussed further yonder.

Synchrony is often amazing, and our resemblance to metronomes can be mind-boggling, too. Since so many species share a superficial similarity in synchronizing their behavior, the best starting point to understand the phenomenon is the biological approach.

Maasai tribesmen jump in synchrony.

BIO: It’s striking that we don’t synchronize every kind of behavior. In raising a toast at a dinner, we all lift our glasses simultaneously; but we don’t all fork up the same foods a moment later. Cyclists in a race respond to a change in the wind together, yet only a few will make a serious try to be first at the finish. We are synchronized by our reflexes and our learned skills, but not so much in the motives that drive us.

What does get synchronized are functional units of movement, whether they are reflexes or learned skills. Swimmers who jump into a cold pool will synchronize their shivering, but not so much their moans. The functional units are “chunks” of movement like the steps in a ballet.  As we learn a skill, we learn the motor sequences in units that psychologists call chunks. Chunks can then be built into larger pieces of behavior called habits.

But the chunks are what we later will recall as “muscle memory”. For our purposes, muscle is part of procedural memory, which is our memory for skills that is not encoded in language and is hard to explain verbally. How quickly can you tie your shoelaces, a skill encoded in prospective memory? And how long does it take to explain the process to a child?

Actually the term is used in two ways to apply to one kind of memory in the muscles and another kind in the brain. Procedural memory is in the brain. The movements that can be synchronized reflect not only procedural memory but hormone actions on social contact.

The other kind is in the muscles, making it easier to retrain a muscle that was formerly fit. There’s real physiology behind it.

Molecular biologists (not to mention Rick and Morty) have a different meaning for muscle memory that applies to the changes inside muscle cells that survive after many workouts. It will not be needed for this discussion, but it has become a big deal for physiologists, and it may make it easier for everyone to get back in shape.

PSYCHO: Synchronized movements arise partly out of our having the same body structure, which tends to make motor learning similar for all of us. Synchronization often makes us feel good, too, because our brains all have the same reward circuits. Both of these aspects of synchrony are obvious in dancing. which is becoming an ancient memory. (Is it any consolation that figure skating may at least be declining faster?)

Although strychnine poisoning can make our skeletal muscles contract without any inhibition, it does not contribute to dancing because it impairs coordinated movement. Dancing depends on us all having muscles and bones all work the same way. For example, when the biceps muscle, a flexor, contracts, the triceps, an extensor, relaxes–and vice versa. This is called reciprocal inhibition. (Would more diverse bodies or new kinds of musical instruments impair synchrony by imposing a cacophony of codes for movement?)

Our skeletal muscles* often work with our bones as levers for movement. When two muscles exert opposing movements they are called antagonists, and a moment’s glance at Figure 11.3 on p. 342 will reveal how this is true of the biceps and triceps.

If you dance with a partner, you depend on your partner’s movements being complementary to yours, which transports you both around the dance floor. This is not physics, much less muscles and bones. It’s the mind, putting together muscle memories that guide each step.

This is not to trivialize the skill, as some of the procedural memories are quite sophisticated. For example, I am not alone in lacking this skill, which is so important to some dancers.

Apparently ballet dancers can adapt to spinning, also. Skaters may learn a similar skill, and they can be helped along by spotting, as you described. I realize you must know this, but for those of us who are not dancers or skaters  or aerial gymnasts, it’s sort of interesting.

Dancers have other mental and physical skills to pass on, but some folks won’t reach first base, so to speak, though there’s hope for some.

Yet what psychologists express simply, physicists are scratching their heads over. Fouettés are apparently a little hard to explain, yet the conservation of angular momentum is something we can all grasp, just like that other spinning problem.

What is harder to explain is why the ballet dancer–or any spinning object–doesn’t fall over. People who are handy with differential equations do a valiant job, but I’d like to stop here.

What we can synchronize with other people depends on sharing the same building blocks of movement. These building blocks are not just similar muscles and bones but the same learning. Even a good drummer will not succeed in a marching band if (s)he has not learned to march with other band members on a drill field.

Muscle memory, part of procedural memory, is the basis of motor learning and therefore of synchrony. It is the storage and recall of skills that allow us to relearn a golf swing or play an arpeggio while you read the newspaper–or type in a familiar password. Although learning is conscious and takes effort at first, during its organization in the cerebral cortex, overlearning prompts a transfer to the basal ganglia and cerebellum, where a sequence of movements for, say, a tennis serve, can be triggered as a whole, without conscious participation. In fact, conscious participation will ruin the performance. Consciousness seems mostly to be a function of the cerebral cortex, and an overlearned skill moves from the cortex to unconscious subcortical control. That handoff frees up the cortex for new conscious learning (or should, if a lot of us didn’t suffer from Consciousness Deficit Hypoactivity Disorder).

The traditional viewpoint puts thinking in one part of the mind and movement in another, lower part: mind versus body. But the findings on embodied cognition show that such compartmentalization is a false dichotomy. Movement can support cognition, and movement and cognition are “deeply intertwined“. Gestures can help learning and the way we write can improve both our learning and our thinking (about keyboards?). Movement guides the mind and pervades emotion.

The upshot is that when we synchronize our motion with that of other people, we experience thoughts and emotions that we would not experience otherwise.

*Note that the girl in the picture is shown with no muscles in her fingers. That’s because our fingers lack muscle.

SOCIAL: Interpersonal synchrony depends on our having movement sequences that reflect the way that neurons are wired and the pleasure or relief from pain that it provides. Synchrony with a particular impact appears in the form of rituals, varying in tightness and looseness, which help to regulate emotions, performance goals, and social bonding.

In times of uncertainty, rituals can allay anxiety. Athlete’s superstitions show us that personal rituals can help, though community rituals seem to be a greater resource, increasing self-esteem even as they strengthen the community, in infants as well as adults, and even when the hoped-for outcome is nothing more than luck.

One cautionary warning: We aren’t exploring human instincts here. Whatever instincts may be—and they are usually labels for whatever we don’t understand about the causation of behavior—they do not include interpersonal synchrony, which develops not in isolation but through interactions with other people. Following the report that infants—”neonates”—less than two weeks old were able to imitates gestures like sticking out the tongue, popular accounts appeared, referring to a hard-wired instinct for mimicry. Skeptical articles questioned the neonatal origin of the imitation, some suggesting that maybe it appeared after a few months’ experience, when in fact research had already made it fairly clear that imitation didn’t become evident until the second year.

Probably interpersonal synchrony is different from social contagion, too. Mimicry is not a rare phenomenon. Biologists have explained how Batesian mimicry can be adaptive, and there are other kinds we could explore–Müllerian mimicry and others–but it might be worth wondering if this all applies to humans at all.

Some researchers attribute our ability to learn by imitation (observational learning) to mirror neurons in the brain, although wide regions of the cerebral cortex are involved in imitation generally. We continue to use such mimicry to cement social bonds as we grow up. As you watch close friends converse you can see instances of this in their expressions, postures, and gestures.

Then there’s social contagion to consider. We certainly are moved to laugh, cough, scratch, and yawn and even vomit when others do it.

If these are all cases of mimicry the case for evolution has already been made for us. But it’s such a complex and longstanding question. Would you wear Elvis Presley’s jacket? Have you ever checked out YouTube or Facebook for a viral story?

What’s the alternative to mimicry? Maybe social influence. Communication has evolutionary roots, too.

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