Great Falls tribune. [volume] (Great Falls, Mont.) 1921-current, 1922-07-08
The HQSkin Letter BY e = assss
LIARS AND BLOOD PRESSURE.

Washington. ID. c.. July 5.-Some
day every prisoner at the bar may have
his story scientifically tested for
t~ruthfulness. Blood pressure has been
tried and proved as a guage of decep-
ton. and q method has been evolved by
which an expert can test with reason
able exactness the truth of the spoh-
en- word.
Thus a prisoner may recount calmly
a plausible alibi for a crime. Perhaps
he shows no visible symptoms of fear
or ervousnes But if he is n& tell
ing the truth his blood pressure, over
which he has no control, is reactlng
violently to the fear Of discovery. On
the other hand. if he is telling the
truth however fantastic. his blood pres
sure will bear him out by remaining at
a comparatively normal level.
The blood pressure deception test
has been developed 10 a practical stage.
II was used by the department OF jus
tice in connection with wartime spy
cases. 1t is being used now by a
criminologist of the Berkeley, Cali
fornia, police department.
Here in Washington the man who
developed the test has just tried it on
n negro accused of murder. Evidence
is against the suspect. but the test in
dicates that his alibi is correct. He is
now being held while other suspects
are being traiied.
This illustrates the place which the
deception test will probably come 10
hold in criminal investigation. II will
not be taken as absolute proof of guilt
or innocence. But in a case where the
evidence would convict n 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 rail-
roading a man to jail may be no longer
a frequent occurrence.
The pioneer Of the blood pressure
deception test is Or. William NJ. Mars
ton. professor of psychology at the
American university. DIR. Marston says
that there has been Gome misunder-
standing 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 the tests were
invented some time ago for various
DR.. Marston explain. that
he is the inventor of the blood pres
sure test. but not Of the instrument.
The Deceptive Complex
Working at the Harvard laboratory
in 1913. he evolved the theory that
blood pressure is an indicator Of de-
c~eption. Fear and anger largely con
s~titute the deceptive complex. and
these are the only emotions that in
f~luence to any extent s~ystolic blood
pressure on which the tests are based.
De. Marston found by experiments
that IL anyone attempts TO deceive the
emotion Of fear influences his blood
pressure in definite ways. Even if
the possibility Of detection is remote
the organs respond somewhat to an
inherent fear. It 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 be calls
a sphygmomanometer. the psychologist
made numerous tests which sustained
his theories. Tests were made of per-
sons held by the police department for
theft, drug taking. prostitution, forgery
and bootlegging. After each test was
made DR.. Marston gave his verdict as
to the truth or falsity of the subjects
account. Then the investigation was
continued by medical examination,