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,
12 June
1975
MEMORANDUM FOR:
OTS/CK
SQ1|
ATTENTION:
SUBJECT:
Evidence
for Non- Randomness of "Four-State
Electronic Random Stimulus Generator’
REFERENCE:
OTS/CB Memorandum #75-60
As requested
in
the last paragraph of the referenced
memorandum,
have investigated the data provided
to establish
evidence for randomness.
The basis
for suggesting non-randomnes
is
as
follows
:
Table
1 of the Reference provides data concerning
fre-
quencies of:
A.
Initial States
*
B,
State Transitions
Since the experiment consisted of requiring the subjects
to indicate the next-to-be presented state,
it would seem most
important
to establish that all possible transitions occur
with equal probability.
To test
for possible non- equality
of transitions, we extracted the observed frequencies of non-
identity transitions
to form the following table:
Yellow
Green
Blue
Red
T
-
764
765
790
G
777
-
773
863
B
776
796
.
-
773
R
787
852
803
-*
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This table
follows
;
can be restructured as
a two -by-six
Y/G
Y/B
Y/R
G/B
G/R
B/R
Forward
764
765
790
775
865
773
Backward
777
776
787
796
852
803
The table thus restructured brings together all
non- identity transitions viewed as
state -pairs .
For ^tance.
Col*
1 shows that there were
764 trans it ions Trora the yellow
state
to the green state and there were 777 transitions from
the green state to the yellow state.
Under the hypothe s *®
*
all state transitions are equally fr°bsb J®, a^d equf1l£-ffftfn!!*
by chance the observed frequency with which forward transitions
occur should be unrelated to that with which backward transitions
occur
in the same pair*
This condition
is not ®® t * JS^/back-
a very strong relationship between the observed forward and bach
ward transition frequencies*
The coefficient of
c°trei^.o.,
between frequencies for these two directions, computed aero
s
all six possible non-identity transitions
is
.93,
Cp<
.01}
(see attached graph) *
This
finding shows that there were ,
in
fact, systematic pair-wise biases associated with the electronic
processes by which the transitions were selected.
The finding that the forward and backward transitions
***
closely associated with respect
to joint probability of occurrenc
suggests that they can be considered as having been ^awnfrom
the
same population.
To test this, we computed the
fo™a*d and
*
A
A
—
A
'lift
OuSftTVfiu
frequencies.
They are:
Mean
SB
Forward
788
37.9
Backward
798
28.25
The standard error of the difference between these two means
is
15.59 while the difference between them is only ten; clearly
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these data may he merged.
Merging them provides the following
table
;
Y/G
Y/R
G/B
G/R
B/R
Total
Observed
Frequency
1541
1541
1577
1569
1715
1576
9519
Expected
Frequency
Under Null
Hypothesis
1586. 5
1586.5
1586,5
1586.5
1586.5
1586. S
9519
Chi Square
1.305
1.305
.057
.193
10.408
.069
Total Chi Square * 13 .337 df-5
p».02
In the above table
it can he seen that the large excess of
observed transitions involving the red -green pair
is significant
at
the
.02 level.
Inspection of the observed frequencies reveals
that there are almost ten percent more transitions
involving the
red-green pair than the average of the other five possible non-
identity transitions.
These results suggest that adopting
(for whatever conscious
or unconscious reason)
a strategy of "When green, press red,
when red, press green and* otherwise use the
'pass
button as
much as possible" will increase one’s hit
score.
Osins an
instrument with the above -described characteristics and
strategies such as this is certain to produce "statistically
significant" results, given enough trials and the assumption
of random transition probabilities.
Other biases also exist
which could form the bases of other enhancing strategies but
the above discussion would seem adequate to establish the
existence of non -randomness which we have suggested.
The report available
to us contains data only upon one test
of one instrument.
It must,
therefore, be assumed that the other
instruments demonstrated non-random characteristics of a similar
nature.
Further,
the report does not reveal which subject used
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which instrument so we are unable to ascertain whether or not
subject number
2 *s results could be due to the effects discussed
above , but the magnitude of the effect
is adequate to explain
the results
if one assumes the adoption of a selection strategy
which "capitalises
1 * upon the non -random characteristics which
are demonstrably present.
SGI
I
Attachment
Distribution:
Original
§
- Addressee, w/att
-
LSR File, w/att
-
LSR Chrono, w/att
-
ORD
Chrono, w/att
LSR/ORD/DD/S§T^H ;niav
: 3191
SGI
I
Approved For Release 2000/08/l1)
: CIA-RDP96-00787R0002001 50005-1
ewiriDcmm