Being overwhelmed with useless detail. Lewin attempted such a
psychology; but in the '30s topology was not yet developed to be
a useful tool. In the '50s, however, it is much better developed,
Especially in the form published under the pseudonym of Nicholas
Bourbaki, by the French School. At last we have before us the
Possibility of a psychology that shall be at once rigorous and prac-
Tical.
TH E I NCOM P L ET EL Y O BS ER VAB LE B OX
So far, in this chapter, we have assumed that the observer of
The Black Box has the necessary means for observing all that per-
Tains to the Box’s state, so that he is like a Ship’s Engineer (S.6/2)
113
A N I N T R O D UC T I O N T O C Y B E R NE T I C S
TH E BL AC K B O X
Who faces a complete set of dials. Often, however, this is not so—
Some of the dials are hidden, or missing— and an important part of
Black Box theory is concerned with making clear what peculiari-
Ties appear when the observer can observe only certain compo-
Nents of the whole state.
The theoretical developments are large, and little explored.
They will almost certainly be of importance in psychology; for, to
The psychologist, the individual subject, whether a neurotic person
Or a rat in a maze, is largely a system that is not wholly observa-
Ble; for the events in the subject’s brain are not directly observable
At the clinical or experimental session.
It should be noticed that as soon as some of a system’s variables
Become unobservable, the “system” represented by the remainder
May develop remarkable, even miraculous, properties. A com-
Monplace illustration is given by conjuring, which achieves
(apparently) the miraculous, simply because not all the significant
Variables are observable. It is possible that some of the brain’s
“miraculous” properties— of showing “foresight”, “intelligence”,
Etc.— are miraculous only because we have not so far been able to
Observe the events in all the significant variables.
As an example of the profound change that may occur in the
Observer’s opinion about a mechanism if part of it becomes inac-
Cessible to direct observation, consider the following example.
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The observer is assumed to be studying a Black Box which con-
Sists of two interacting parts, A and Z. Both are affected by the
Common input I. (Notice that A’s inputs are I and Z.)
I
A
↓↑
Z
Observer One can see, like us, the values of both A and Z. He
Studies the various combinations that may lead to the appearance
Of B, and he reports that B appears whenever the whole shows a
State with Z at y and the input at a. Thus, given that the input is at
A, he relates the occurrence of B to whether Z is at y now.
Observer Two is handicapped— he can see only I and A, not Z.
He will find that knowledge of A’s state and of I’s state is not suf-
Ficient to enable him to predict reliably whether B will be shown;
(for sometimes Z will be at y and sometimes at some other state).
If however Two turns his attention to earlier events at I he finds
He can predict B’s appearance accurately. For if I has in succes-
sion the values µ, α then behaviour B will appear, and not other-
wise. Thus, given that the input is at α, he relates the occurrence
of B to whether I did have the value µ earlier.
Thus Two, being unable to observe Z directly, can none the less
Make the whole predictable by taking into account earlier values
Of what he can observe. The reason is, the existence of the corre-
Spondence:
I at µ earlier ↔ Z at y now
I not at µ earlier ↔ Z not at y now.
As this correspondence is one-one, information about I’s state a step
Earlier and information about Z’s state now are equivalent, and each
Can substitute for the other; for to know one is to know the other.
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