Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1922-07-11


truthfulness. Blood pressure has been tried
and proved as gauge Of deception, and a
method has been evolved by which an ex-
pert can test with reasonable exactness the
truth Of the spoken word.
Thus a prisoner may recount calmly a
plausible alibi for crime. Perhaps he shows
no visible symptoms of fear or nervousness.
But II he is not telling the truth his blood
pressure, over which he has no control, is
recacting violently to the fear of discovery.
On the other hand, If he is telling the truth,
however fantastic, his blood pressure will
bear him out by remaining at comparative
1y normal level.
The blood pressure deception test has been
developed to practical stage. It was used
by the Department of Justice in connection
with wartime spy cases. 1t is being used
now by a criminologist of the Berkeley, Cal,
police department.
Here in Washington the man who devel.
oped the test has just tried it on a negro &C.
cused of murder. Evidence is against the
suspect, but the test indicates that his alibl
is correct. He is now being held while other
suspects are being trailed.
This illustrates the place which the de-
ception test will probably come to hold in
criminal Investigation. 1t will not be taken
as absolute proof of guilt or innocence. But
in case where the evidence would convict
man in spite of his plea of innocence the
deception test may lead to. further inquiry
reading man to Jail may be no longer a
frequent occurrence.
The pioneer of the blood pressure decep.
ton is DR.. William M. Marston, professor OF
psychology at the American university. DR..
Marston says that there has been some mis-.
understanding 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 CIV
ing the tests were invented some time ago
for various purposes. DR.. Marston explains
that he is the inventor of the blood pressure
test, but not Of the instrument.
The Deceptive Complex
Working at the Harvard laboratory in
1913, he evolved the theory that blood pres
sure is an indicator of deception. Fear and
anger largely constitute the deceptive COM
pick, and these are the only emotions that
influence to any extent systolic blood pres
sure on which the tests are based. DR..
Marston found " experiments that II anyone
attempts to deceive, the emotion of fear in
fluences his blood pressure in definite ways
Even if the possibility of detection is remote
the organs respond somewhat to an inherent
fear. 1t is not normal to lie, and this de-
parture from normal has its reaction in the
blood pressure.
Using and instrument which is attached to
the arm, and which he calls sphygmomano-
meter, the psychologist made numerous tests
which sustained his theories. Tests were
made of perons held by the police depart
ment for theft, drug taking, prostitution,
forgery and bootlegging. After each test
was made DR.. Mrston gave his verdict as to
the truth or falsity Of the subjects account.
Then the investigation continued by
medical examination, questioning other per-
sons involved or by further detective work.
1t is claimed that the blood pressure tests
were invariably substantiated by the corrobo-
rative evidence.
DR.. Marston says that he has always got
| 100 per cent satisfactory results in making
the tests himself. That is, for him the
| sphygmomanometer has proved 100 per cent
reliable as a detector of deception. Other op-
orators, less alert to psychological factors
in case and less experienced in making the
examinations, have been getting from 80 to
| 100 per cent satisfactory results.
1t is not simple matter to give decep
| ton test. From description of the method
it is readily apparent why an expert must
| give it if it is to be of any value.
A woman may have a normal blood pres
sure of 100. The sphygmomanometer is
| fastened to her arm and the operator listens
| in. Whether the first questions are connected
with the case or not the subjects pressure
would probably jump to 40 and remain
there. novice might at once conclude that
| the subject was not answering his questions
| truthfully, whereas this reaction would prob
| ably be due to a general uneasiness at the
| mysterious proceeding AS the questions pro-
| coed the operator may find that the chart
| he is drawing remains at level of 100 or
| drops off toward normal, indicating that the
subject is truthful in her statements.
Outside Influences Noted
| On the other hand, the pressure may sud-
| denly rise, even reaching a peak of 10 or
| $50 when significant questions are answered.
| This would generally indicate a deception
curve; not necessarily however. To make
| an extravagant illustration, suppose that just