Copy Link
Add to Bookmark
Report
AIList Digest Volume 8 Issue 086
AIList Digest Monday, 19 Sep 1988 Volume 8 : Issue 86
Why we got rhythm (5 messages)
----------------------------------------------------------------------
Date: Thu, 15 Sep 88 09:01:25 EDT
From: "Bruce E. Nevin" <bnevin@cch.bbn.com>
Subject: Re: I got rhythm
Subject: Re: I got rhythm
In AIList Digest for Thursday, 15 Sep 1988 (Volume 8 : Issue 83),
we read the following from Phil Goetz (PGOETZ%LOYVAX.BITNET@MITVMA.MIT.EDU):
PG> Here's a question for anybody: Why do we have rhythm?
|
| Picture yourself tapping your foot to the tune of the latest Top 40
| trash hit. . . . Different actions require different processing
| overhead. So why, no matter what we do, do we perceive time as a
| constant? Why do we, in fact, have rhythm? Do we have an internal
| clock, or a "main loop" which takes a constant time to run? Or do we
| have an inadequate view of consciousness when we see it as a program?
The music has rhythm. The foot tapper has synchrony.
There are lots of physiological processes that are rhythmical in nature,
and with which one can synchronize other behavior. Some are ongoing,
notably heartbeat, breathing, and brain waves. Others are easier to
start and stop, like walking or running.
However it's done, it seems straightforward for organisms to set up an
ad hoc oscillation, as in shivering, rubbing hands/paws together,
pacing. For such activities it seems plausible that the governing
mechanisms are encapsulated and require little attention. Minsky's
_Society of Mind_ is a good place to look. (Open question how ad hoc
they are, perhaps they are in synchrony with preexisting rhythms.)
The musicians (and not just the toe tappers and other dancers) are also
synchronizing their actions with respect to existing rhythms, even if
only to a beat counted out by the leader of the band at the outset
(a-one, and a-two . . . ). Where does the initiating musician get the
rhythm? Heartbeat? Imagining/ remembering oneself walking? (That is
the meaning of `andante'.) Imagining/remembering people dancing?
Certainly, once they have started, members of the band must synchronize
their playing with one another (ensemble).
What happens when the foot tapper is preoccupied with other thoughts?
The tapping doesn't slow down, it can't because synchrony is essential
to it. Instead, it becomes sporadic. The process itself gets dropped
and picked up again. Just so, new musicians have to practice keeping up
a steady rhythm despite being distracted by other things (coordinating
fingers on the instrument, remembering the words in a song). Their
novice performance is typically marked by interrupting and resuming the
given rhythm. If a practicing pianist slows down in a passage where the
notes are small and close together, it is mostly to coordinate the
fingers physically, not to free up processing time. (Preferred way is
to slow the whole piece down and play at a constant tempo.)
It seems to require a certain amount of attention to maintain a rhythmic
behavior, presumably above the threshold required to maintain synchrony.
But that's not much, as anyone can attest who has discovered her or his
body swaying or falling in step or tapping unawares during a
conversation.
Rhythm (cyclicity) is an environmental given. Resonance (entrainment)
is also a given in physics, ecology, psychology. Music and dance play
with these givens.
Seems to me that cyclicity and synchrony has survival value in that it
helps make organisms predictable to one another. Creatures that become
prey are typically those unable to maintain synchrony with their social
group because of sickness, etc. Stricking examples of synchrony include
flocks of birds, schools of fish. We have recently heard of LIFE
emulations of flock behavior involving little processing overhead.
Perhaps the problem is not how do individuals synchronize in a flock,
but rather how does individuation happen out of the flock, and to what
extent. It seems plausible that the experience of being an independent
ego that we humans cherish is an illusion. To maintain such an
illusion, we ignore counterevidence. A pretty good definition of
unconscious behavior. (Say, did you know your foot was tapping?)
Bruce Nevin
bn@cch.bbn.com
<usual_disclaimer>
------------------------------
Date: Thu, 15 Sep 88 10:32:21 EDT
From: hayden@prism.TMC.COM (Hayden Ridenour)
Subject: rhythm
> So why, no matter what we do, do we perceive time as a constant?
Who does this? Try keeping track of time when you're in a hurry to get
seven different things done at once and compare it to how slow time passes
when you're waiting for something. The time passes at the same rate, but
we don't perceive it at the same constant rate.
As for why you can be tapping your foot to the rhythm of a song you're
listening to while you're doing other things: you have the music as a
timing source. You could think of it as an interrupt process keyed to
the rhythm of the music.
~?
~h
------------------------------
Date: Thu 15 Sep 1988 13:44 CDT
From: <UUCJEFF%ECNCDC.BITNET@MITVMA.MIT.EDU>
Subject: RE: I got rhythm
>
>It comes down to this: Different actions require different processing
>overhead. So why, no matter what we do, do we perceive time as a constant?
>Why do we, in fact, have rhythm? Do we have an internal clock, or a
>"main loop" which takes a constant time to run? Or do we have an inadequate
>view of consciousness when we see it as a program?
>Phil Goetz
>PGOETZ@LOYVAX.bitnet
Being both an international jazz recording artist and computer programer,
with a growing background in AI (but not the AI religion),
I will join this jam session on this tune called "I GOT RYTHM".
I really dont know how much I can answer Phil's questions,
but I can give some perspective on how a musician or drummer or someone
with good time views rhythm.
Start out by looking at some of the terminology surrounding rythm, we say
something is "in a groove" or "in the pocket" or "it swings".
The first two imply precision, ease, and continuaty, while "swing" implies
motion. All three terms imply "autonomy", and that is so true.
When something "swings", the music goes by itself.
"Time" is another important word. For musical genres which are known to
have advanced forms of rythm, "TIME" is a very mutable characteristic.
By laying slightly back of the beat, you make the sound float in the air,
and by pushing ahaed slightly, you can give music drive and fire.
To be able to master it and use it, I would tend to say it involves all
parts of the human psycho physical structure... You certainly excite your
nervous system, you need your reflexes to control the muscles that are tapping
the foot or playing the instrument, the emotions are involved, and on the
mental level, you need to concentrate and use your ability to image things.
Then of course there is the musical idea itself behind the whole thing.
Certainly if you are lazily tapping your foot and not paying too much
other attention, these other charactaristcs will take a lessor role.
But to the extent you are tapping good time, you must have the automatism
there. Where this comes from, I don't know, but that is how you feel it.
Therefore, I would suggest that we do not perceive time as a constant.
We don't in ordinary life, and we don't in music. If we are really
getting into a piece, we could listen for hours and it will not seem
like a long time. I heard a live performance of Stavinsky's La Sacre du
Printemp, even though it is 40 minutes, it went by like 10 minutes.
Isn't it a famous quote of Einstein when asked to explain relativity,
and he said "If you are sitting next to a beautiful girl, hours go by
like minutes, but if you are sitting next to ..., minutes seem like hours"
Phil asked about programming this. Since I have become disillusioned at
how generic most jazz today sounds ( Yes Wynton, that's you) my musical
direction has been to make a One Man Digital Band with an Atari ST MIDId
to my MIDIcapable trumpet and a variety of synthesizers and drum machines.
I have been programming a walking bass line. It reads my trumpet and
figures a bass line in real time. If I change keys, It changes keys.
If I hold a note. It holds a note. etc...
The only way to program rhythm and make it sound "human", is to study humans,
identify the slight delays or anticipations, and try to come up with a
scheme so it is related to the appropriate information of the other music.
This itself is a creative act on the part of the human being.
There are no fixed schemes on determining what is approprate, one has to
do the research and evaluate the results. Whehher you can get it down to
an adaptive filter is anyone's guess.
At present there are some people working in this area, and there are even
some commercial products out that based on some of the concepts I have
presented. There are devices which are designed to take a perfectly timed
computer generated drum sync track and massage the pulses so it will give
a human feel. On the unit are switchs to make it sound like a
60s Motown feel, a 70s L.A. sound, brazillian, and on and on and on.
I think I have said enough, I hope that answer's Phils question. If not
I hope that this was interesting otherwise. If not, solid..........
Jeff Beer, UUCJEFF@ECNCDC.BITNET... Chicago Ill....
"I'll play it and tell you what it is later"... Miles Davis
------------------------------
Date: Fri, 16 Sep 88 03:07:35 EDT
From: Joseph.Tebelskis@F.GP.CS.CMU.EDU
Subject: Re: I got rhythm
In V8 #83, Phil Goetz asks:
> It comes down to this: Different actions require different processing
> overhead. So why, no matter what we do, do we perceive time as a constant?
> Why do we, in fact, have rhythm? Do we have an internal clock, or a
> "main loop" which takes a constant time to run? Or do we have an inadequate
> view of consciousness when we see it as a program?
First you need to realize that the computer is a poor metaphor for the brain.
Modern computers are organized around a single CPU through which all the
computations must flow, while memory plays a passive and underutilized
role -- hence the CPU is called the "bottleneck" of modern computers.
As you noted, multitasking slows down individual tasks on such machines.
In contrast, the brain has a hundred billion processors (neurons), and its
vast memory is active rather than passive. Its various modules operate in
parallel, so they don't slow each other down; this is why we can perceive
time as a constant no matter what we're doing. Also, the brain does not
execute a high-level "program" of instructions: its operation is guided by
autonomous physical processes at the neural level. From this neural level
emerge all the diverse cognitive phenomena, including rational thought,
emotions, and consciousness. However, the only emergent phenomenon which
maps well onto our computer programming paradigm is rational thought -- so
that's what symbolic AI has always concentrated on. The emergent phenomenon
of consciousness is "made of the same stuff" at a low level, but it just
cannot be approximated satisfactorily at the symbolic (programming) level.
With regard to rhythm and parallelism, I currently visualize the brain
as an extremely complex "resonance chamber". At various scales and
physical locations within the brain, different subnetworks can be resonating
in different ways. The simplest kind of resonance would be a cyclical
reverberation of activity at a characteristic frequency; such a pulsing
signal could control your foot as you tap out a rhythm. More complex types
of resonance may simultaneously be in operation elsewhere in the brain,
controlling unrelated cognitive tasks such as doing a math problem. I
suspect that subnetworks of the brain use complex resonance patterns to
symbolically represent brief progressions of events, such as perceptual
sequences, fast motor procedures, and internal state transitions. Such
temporally encoded symbols, recursively telescoped together in the
"resonance chamber" of the brain, may account for the natural emergence of
a hierarchy of symbolic representations for event progressions spanning
arbitrary time scales. It is also conceivable that resonant representations
avoid interfering with each other in the brain just as physical waves do,
by superposition.
Joe Tebelskis, connectionist
(jmt@f.gp.cs.cmu.edu)
------------------------------
Date: Fri, 16 Sep 88 14:59:08 bst
From: Bert Hutchings <bert%aiva.edinburgh.ac.uk@NSS.Cs.Ucl.AC.UK>
Subject: Re: I got rhythm
In article <19880915011053.7.NICK@HOWARD-JOHNSONS.LCS.MIT.EDU> Phil Goetz
asked "Why do we have rhythm? . . . Why do we, in fact, have rhythm?"
Most of us have, but... My wife taught music to young schoolchildren and
found an occasional exception. We know one rhythm-deaf adult too, unable
to keep a beat, or to distinguish a regular one from a slightly irregular
one. I estimate between 1/50 and 1/200 of people have this condition.
------------------------------
End of AIList Digest
********************
