Perth Amboy evening news., 1922-07-08
LIARS AND BLOOD PRESSURE
TESTED BY u. S. EXPERTS
Daily Letter by Frederic j. Haskin

WASHINGTON, D. c., July s.
Some day every prisoner at the bal
may have his story scientifically
tested for truthfulness. Blood pres
sure has been tried and proved as
a gauge for deception and a method
has been evolved by which an ex-
pert can test with reasonable ex-
actness the truth of the spoken
word.
Thus a prisoner may recount
calmly a plausible alibi for a crime.
| Perhaps he shows no visible symp-
toms OF fear or nervousness. But
* he is not telling the truth his
blood pressure, over which he has
no control. is reacting violently to
the fear Of discovery. On the other
however fantastic, his blood pres
sure will bear him out by remaining
at a comparatively normal level,
The blood pressure deception test
las been developed to a practical
stage. 1t was used by the Depart
ment of Justice in connection with
wartime spy cases 1t is being used
now by a criminologist of the Berk-
eley, California, police department.
Here in Washington the man who
developed the test has just tried 1t
on a negro accused Of murder. Evil
dence is against the SUSPECT, but the
test indicates that his alibi Is cor
rect. He is now being held while
other suspects are being trailed.
This illustrates the place which
the deception test will probably
come to hold in criminal investiga-
ton. 1t will not be taken as abso-
lutte proof of guilt or innocence. But
~ n ,oea urhara Tho ayidanna would
convict a man In spite of his plea
OF innocence the deception test may
lead to a further inquiry into other
clues. With the test in use railroading
a man to jail may be no longer a
frequent occurrence.
The pioneer of the blood pres
sure deception test is DR.. William
M. Marston, professor Of Psychology
at the American University. DR..
Msrston says hat there has been
some misunderstanding about his
work. He uses three different kinds
of deception tests of which the blood
pressure test is the most reliable.
All OF the instruments adapted for
use in giving tho tests were invented
some time ago for various purposes.
DR.. Marston explains that he is the
inventor of the blood pressure test,
but not the instrument.
Deceptive Complex
Working at the Harvard Labora-
tory in 1913, he evolved the theory
that blood pressure is an indicator
Of deception. Fear and anger
largely constitute the deceptive COM
pick, and these are the only emo
items that influence to any extent
systolic blood pressure on which the
tests are based. DR.. Marston found
by experiments that il anyone at
tempts to deceive the EMOTION OF
fear influences his blood pressure in
definite ways. Even if the posi-
bility of detection is remote the Or
sans respond somewhat to an inher-
ent fear. 1t is not normal to lie
and this departure from normal has
its reaction in the blood pressure.
Using an instrument which is at
tached to the arm, and which he
calls a sphygnomanometer, the psy-
chologist made numerous tests
which sustained his theories. Tests
were made by persons held by the
police department for theft, drug
taking, prostitution, forgery and
bootlegging. After each test was
made DIR. Marston gave his verdict
as to the truth or falsity of the sub
Ject's account. Then the investiga-
ton was continued by medical ex-
animation, questioning other per-
sons involved. or by further detec-
tive work. 1t is claimed that the
blood pressure tests were invariably
substantiated by the corroborative
evidence.
DR.. Marston says that he has al
ways got 100 per cent. satisfactory
results in making the tests himself,
That is, for him the sphygmoman-
ometer has proved 100 per cent. re-
liable as a detector of deception
Other operators. less alert Il psy-
Geological factors in a case. and less
experienced in making the examina-
tons. have been getting from so tc
100 per cent. satisfactory results.
1t Is not a simple matter to give
a deception test. From a description
Of the method it is readily apparent
why an expert must give it if it il
TO be of any value.
A woman may have a norma
blood pressure of 100. The sphyg,
momanometer is fastened to hei
arm and the operator listens in
Whether the first questions are con,
nected with the case or not the sub
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