From Bob Clark (930817.17:45 pm EDT)
Additions to and modifications of the Original "Portable
Demonstrator" were presented Sunday morning, August 1, 1993. The
summary and discussion is in several parts, to be posted as prepared.
IV. is still tentative.
I. PRESENTATION. Observer's View. "DEMO I, PRESNTATN - RKC"
II. COMMENTS. Demonstrator's View. "DEMO II, COMMENTS - RKC"
III. DISCUSSION. Experimenter's View. "DEM III, DSCUSSN - RKC"
IV. (tentative) EXTENSION. Engineer's View. "DEM IV, EXTENSN - RKC"
···
----------------------
I. PRESENTATION. The Observer's Viewpoint.
Introduction. This presentation was based on my recollection of the
original "Demonstrator" as we worked it out in the late 50's.
"LCS," refers to "Living Control Systems, Selected Paper of William
T. Powers," The Control Systems Group, Inc, Gravel Switch KY., 1989,
"A General Feedback Theory of Human Behavior: Part II" pp 25-45.
This paper was originally published in "Perceptual and Motor Skills,
1960, 309-323.
"BCP" refers to "Behavior: The Control of Perception" William T.
Powers, Aldine de Gruyter, Hawthorne, New York 1973, p 246, where it
is also described in condensed form.
These descriptions are taken from LCS, modified for this situation.
For Comments, Explanation and, possibl Extention (?), see II, III, and IV.
I did not discuss the demonstration beforehand so that the audience
was free to draw its own conclusions. Instead, I included the new
parts of the demonstration within the familiar framework of the
original "Portable Demonstrator." Incidentally, some parts that are
now interesting were already included in the original. They were
ignored previously because of concern with other aspects of the
situation.
The following summary is a condensed version of the actual
presentation. This emphasizes the major elements composing the
essence of the demonstration, and omits all discussion that occurred
at that time. It is hoped that this description is sufficient for
replication by those who are interested in making their own
independent observations.
The viewpoint used here is that of an Observer.
A. From p 28, LCS:
"S extends his arm in front of himself, with instructions to hold it
steady, and E places his hand lightly on top of S's. E gives a sudden
sharp downward push, and S's arm appears to rebound as if on a spring.
An electromyograph verifies that this is an active innervated
correction and not simply muscle elasticity."
B. From p 29, LCS:
"E now instructs S to extend his hand as before, and E places his
hand on top of S's. Now E tells S to swing his arm downward as
rapidly as he can, as soon as he feels E push down. E's hand must
begin in contact with S's to make the push as sharp and unexpected as
possible."
Interpretations are omitted here, will be discussed later:
"Immediately after the push," S's arm returns "to its initial
position." . . . "Then, after the return swing is nearly
completed," S's arm accelerates "downward as requested."
C. From p 30, LCS, modified to fit this presentation:
E instructs S to extend his hand as before, and to point one finger.
E places his hand on top of S's hand. E also extends the index
finger of his other hand, placing it 12 to 18 inches from the initial
position of S's finger. S is instructed, as soon as he can after E's
push on S's hand, to touch his finger to the extended finger of E's
other hand.
However, at the push, _E shifts his target finger 4 or 5 inches_, in
any arbitrary direction.
The first two reactions (A & B) remain visible, and at the end of S's
rapid swing a third phase appears. S's finger comes nearly to a stop
_near where E's finger was initially,_ and then begins a much slower
corrective movement quite different in nature from the first two
actions.
D1. From p 31, LCS,also modified to fit this presentation:
E instructs S to extend his index finger and track E's index finger
as accurately as he can. E then moves his own finger up and down (6
to 12 inches, top to bottom) at some arbitrary tempo. This was
approximately a sine wave. Soon S succeeds in matching E's movement,
initially displaying irregularities resembling those in C.
D2. D1 continued. E then changes to a horizontal movement at the
same tempo. Again S matches the new direction after brief
irregularities resembling those in C.
D3. D1 further continued. After E's repeated arbitrary changes
between horizontal, vertical and other movements, all at the same
tempo and approximating a sine wave, E abruptly changes his tempo. S
soon matches the new tempo, after brief irregularities resembling
those in C.
D4. D3 continued. After repeated changes in tempo, while retaining
the same top and bottom positions of movement, E changes to sharp
movements between top and bottom positions, replacing the sine wave
with a square wave. The previous tempo is continued, and S matches
the new movements, after brief irregularities resembling those in C.
D5. D4 continued. The square wave is continued with repeated
changes in direction, amplitude and tempo. S continues to display
delays resembling those in C. After a few repetitions, E begins to
use irregular time intervals between his movements. He retains the
same fixed end points he has been using, thus continuing to form a
square wave, but with irregular durations between movements. These
range between very short to (almost) intolerably long. There is no
longer any definite tempo, for S to anticipate!
E. After S has become familiar with repeated changes in the
amplitude, direction and tempo of the simple oscillatory movement of
E's finger, E drops the hand he has been using to his side and picks
up the same pattern with his other hand. S, uncertain whether to
continue tracking with the same hand or to change the other hand,
continued with the same hand. After S has become familiar with
changes between hands, as well as changes in amplitude, direction and
tempo of E's movements, E drops both hands and begins nodding his
head in the same tempo. At this point, S ceased any attempt to track
anything.
F. Three people are needed for the following. The three
participants are S1, S2 and C. The situation is the basic tracking
case, D1. Initially S1 can be tracking S2, or vice versa. Any
simple form of track can be used. After the tracking is established,
C calls "Bob" or "Chris," the names of S1 and S2. Whoever is named
is to provide the "track" and the other is to be the "tracker." Some,
unspecified, time after the new tracking is established, C calls
again. It may be a repeat of the previous, or may require a change
between the tracker and the "trackee." With fairly long time
intervals between switches, the change works out rather well.
However, if the time interval is gradually reduced, the participants
tend to become more confused as to which is which, and stop in
confusion.
The formal Presentation ends here.
---------------------------
Comments and Discussion are to be posted separately, later.
Regards, Bob Clark