Tim Perper here.
Some points to add to Rick Marken's discussion of thermostats and of
synchronization (labelled "From Rick Marken (980202.2130)"). I go into some
detail below, and apologize if the length is troublesome to anyone. If it
is, please let me know.
1. Let me give a few more details about synchronization in the context of
Rick's comment
RM
I would Test for synchronicity by having one party make a predetermined
sequence of movements; if the other party mirrored those moveents I'd start
thinking that the perception of synchronous movement was, indeed, under
control. But I have the very stong suspicion that whateversynchronous
movement >is seen in courtship is a side effect of people controlling for
other, much >simpler perceptions.
What you're describing in sentence #1 can be called "imitation" or
"mimicry," allowing us to speak of the "model" -- the person who is making
the predetermined sequence of movements -- and the "mimic," the person who
does or does not mirror them. However, there seems to be more to movement
and postural synchronization than mimicry of a model. Let me explain.
1a. I'm visualizing a man and a woman in a bar, in complete synchrony.
Their behavior may sound outlandish and remarkable, but it is very common
-- and occurs in many settings other than bars! However, anyone can visit
a bar and look for synch, so let's talk about bars. (I've done extensive
observations in a variety of settings, not merely bars.) The following
descriptions will be very detailed, because the details are absolutely
crucial.
Thus, he and she are sitting at the bar, facing each other, he on the left,
she on the right, turned fully to face each other, gazing at each other and
talking. He is has his left forearm and hand on the bar, and she has her
right forearm and hand on the bar (so-called "postural" mirror synch).
Now, he glances at his drink on the bar between their facing hands, reaches
for it with his RIGHT hand, picks it up, moves it toward his mouth, sips,
and puts it down. However, she too has been moving throughout the
interaction.
Broadly, there are two rough-and-ready sorts of synchrony that can be
conveniently distinguished as the ends of a spectrum. One I have called
"counter-synchronization" (in my 1985 book Sex Signals). It goes like
this. As he reaches for his drink, she looks at hers; as he picks it up,
she reaches for hers; as he moves the glass towards his mouth, she is
picking up her drink; as he sips, she is moving the glass; as he puts it
down, she sips; and then she puts it down. IF the behavior occurs EXACTLY
as I described, then there is a discernable *lag* between his every
movement and hers.
When I first saw synch in such settings -- some 20 years ago -- the first
thing I thought of was mimicry, as Rick also did, and therefore thought of
modelling and mimicry. But continued observation disabuses one of the
idea that lagged synchronization is the whole story. Thus, we will also
see something ever so slightly different: he reaches for his drink, and
picks it up, and she glances at hers and reaches while he is picking it up.
(This is the *identical* beginning.) But, then, as he starts to sip, and
her arm is lifting her drink, her movement *accelerates* so that she starts
to drink while he is still drinking. They drink in synchrony for a moment,
and then put their glasses down simultaneously. Counter-synchronization
has become mirror synchronization.
As we continue to watch, we will see them sip their drinks again -- and
next time, she reaches, and so does he, but with a *shortened* lag between
her movement and his. They again end up in mirrored movement synchrony,
but you'll see that the duration of their *mirrored* synchronization is
longer. Eventually, as we watch, we will see them enacting the entire
sequence without any lag discernable to the naked eye of the trained
observer. (I have not done films of these interactions, so I have not done
frame-by-frame movement analyses. Even so, I suspect that in mirror
synchrony, there is still a lag, but it is very short.)
Now it is much harder to use a simple, time-lagged "model and mimic"
explanation for what has happened. In fact, I have seen people try to
mimic the other's behavior, but the results are only very partial. Thus,
if he is trying to mimic her, he will mimic only what he perceives
*consciously* and feels is salient to his mimicry. He may reach for his
glass a moment after she has done so (she is the model, he the mimic), but
he will not mimic her other movements, e.g., how she moves her other hand
(her right -- it's resting on the bar). She may touch her glass with her
right hand while she is reaching with her left. That movement he does NOT
imitate, but merely leaves his facing hand (his left) unmoved, or perhaps
even takes it off the bar as he reaches with his right hand for the drink.
Now, we, the observers do NOT see full synchronization at all, but only
very partial and incomplete synchrony. Yet he may believe that he has
imitated her -- mirrored her behavior, if you like.
1b. Rick suggested in his second sentence that synchronization is a side
effect of controlling for something else. That of course is possible, but
I suggest that synchronization is the controlled variable itself (or
something very closely related to it). What I mean is this.
Although I am dubious about gunnery robots exhausting the full range of
PCT, my doubts were not directed to kinesiological episodes like this one.
It is now very easy to discuss synchronization as a controlled variable.
Thus, the variable probably being controlled is the DIFFERENCE between
one's own bodily positions and those of the partner. If one again wades
through the description above of how counter-synch becomes mirror synch,
you'll see how each person is continuously **minimizing** the differences
between their postures. What is crucial is that A minimizes the difference
with B, while simultaneously, B is minimizing the difference with A.
So far as movement synchrony is concerned -- for example, her speeding up
to drink at the same time he does -- the controlled variable appears to be
rate of movement (velocity, meaning both speed and direction). Again the
principle appears to be to MINIMIZE differences in velocity. If so, then
synchronization occurs because posture and movement veolcity are in fact
the controlled variables.
However, perhaps someone will now object -- it is a reasonable objection --
that my description and my observations are contaminated by my (honest by
misled) effort to maximize the goodness of fit between description and what
a servomechanism might easily produce. Well, whoa there! Remember, *I'm*
supposed to be the one who knows no PCT (vide several postings asking if I
know anything at all about it.) But the answer is that I did NOT create
this description to fit PCT, because when I was doing the work first, I had
never even heard of PCT. So let's set *that* aside -- no, I'm not trying
to make the observations fit theory.
Instead, these observations are very easily performed by a servomechanism
whose perceptions involve the other's bodily postures, such that it
controls its OWN bodily postures to minimize the difference between self
and other. So it is not a matter of deliberate mimicry, but of
minimization of a difference between signals. Likewise, velocity (speed and
direction) seems to be the controlled variable during movement synch.
Now, I'm perfectly prepared to say that the other's body postures and
velocities provide "reference" signals, and the controlled variables are
one's own postures and velocities of movement. However, because the two
are interacting, the matter becomes trickier. Thus, the reference signal
for me is YOUR bodily posture, whereas the reference for you is MY bodily
posture. But your bodily posture has been controlled to reduce the
deiviation between it and my posture, so when I use your body posture as my
reference signal, I am actually using my OWN posture, as reflected through
you with a slight lag, as my own reference signal. Likewise, you are doing
the same. We can call such things reciprocal or mutual interaction,
because control is now SHARED between the two interacting units.
By shared, I mean that although we each have independently existing control
mechanisms (our physiologies belong to different bodies), it is no longer
easy to determine unambiguously what the reference and controlled signals
are. One can do so if one looks ONLY at one individual, but when one looks
at both together, one sees that each reference signal contains information
about -- has been previously influenced by -- self's controlled variable.
And vice versa. And for each person.
The result is that we have a system in which control is reciprocal.
Actually, as a biologist, I tend to use the word "regulation" rather than
"control," but, allowing for a difference in terminology, the system has
interconnected components that regulate each other's actions. Such systems
can be extremely stable.
2. A propos of the discussion of periodicity and quasi-periodicity. It is
theoretically possible for a system such as the above to initiate
oscillations. It depends on various time constants in the system.
Thermostats will do this, and hence an amusing story.
When I was working in the pharmaceutical industry, we built a small
temperature controlled box (not important why). It had to hold 37 degrees
Celsius, and so we used a light bulb as a heater. The box had a
temperature sensor -- a simple bimetallic strip used as a switch -- that
activated a small electric fan in a vent and turned off the light bulb.
Since room temperature is much lower than 37 degrees, the contraption
started with the light bulb on. The inside of the box would warm up
slowly, and eventually reach the upper set point of the switch. The bulb
went off and the fan started to hum, blowing warm air out of the box. This
cooled the box, and eventually the temperature dropped to the lower set
point, and the switch would open. The fan would turn off and the bulb
would turn on. One of these devices had a fairly noisy fan. And so the
blasted thing would be silent for a while, and then start to buzz as the
fan went on. Then it would be silent, and just as one became comfortable
with the quiet, it would start to buzz again. We finally put the thing in
the basement. The period was about 10 minutes. Enfuriating.
Note that regular oscillations could occur because ROOM temperature was
itself thermostatted, and remained quite constant during the operation of
the box. That meant that the box cycled quite regularly. (Periodicity is
determined by various time constants, like how long it takes to cool the
box or heat it up.)
However, people in synch can also start to oscillate, if the time constants
are right. Counter-synchronization itself provides some examples. Thus,
he's on the left, and they have put down their drinks, and he leans forward
slightly toward her. She has three choices: to lean towards him, to stay
put, or to lean away. In mirror synch, she leans forward, but in
counter-synch, she leans back. (Like this: //) One's first impression is
that she is leaning back to convey her avoidance of him, but continued
observation dispells the idea. Thus, perhaps embarassed by having come to
close to her and having elicited an what seems to be her avoidance
reaction, he leans back, away from her (\/). And now she leans *forward*
towards him (\\). So he leans towards HER, and SHE leans back (The angles
are about 10-20 degrees or so.) This can continue for a while. If you
visualize their movements, you'll see that they are oscillating.
How come? The preceding can occur if each person is trying to stabilize
their proximity to the other but one of them has, for whatever reason,
moved closer. You may ask why they both don't end up permanently like this
// with both leaning. One answer is that the position is uncomfortable,
unless one of them is leaning against a wall. So one of them moves
forward: /\ followed by re-stabilization of proximity \\. And so it
repeats.
But then they shift,and start this: /\, \/, /\. \/, and so on, now in
mirror synchrony.
What just happened?
"Oho," we observers cry out (silently, though). We have just seen an
*escalation.* Notice that in this position /\, their faces are very close,
and when they're like this \/, their hips are close together. Their
behavior has become more intimate.
Do people actually do this in public? Yes. Is it common? Yes.
And so I am suggesting that the controlled variables are (a) the difference
between posture of self and other, controlled so as to *minimize* such
differences (this will give postural synch), and (b) proximity, controlled
so as to stabilize their distance (which will give movement synch). Then
comes an escalation, and their intimacy increases as they shift to mirror
synchrony, where proximity is controlled so as to enhance or increase their
(intimate) proximity. Are more things involved? They surely are, but
these patterns lend themselves to a fairly simple feedback analysis.
Notice, however, that a HIGHER level system has to intervene at the
escalation point, because otherwise the system will remain forever in the
preceding state (not really forever, but until the bar closes!).
3. Is this PCT? Well, you're the experts, so you tell me. If it isn't,
then I'll be disappointed, because it seems that it should be the kind of
thing that PCT is *very* good at explaining!
Tim Perper