Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1881-05-07
MEASURING THOUGHT.

Doctor Mosso, of Turin, has invented a
machine called the plethysmograph, by
means of which, it is claimed, the quantity
of blood consumed in the nervous action
caused by any mental operation may be ac-
curately measured. The following descrip-
ton of the machine and its workings has
been given by Prof G. F. Barker in an ad-
dress before the American Association OF
Science
The forearm, for example, being the
organ to be experimental on, is placed in
cylinder of water, and tightly inclosed.
A rubber tube connects the interior of the
cylinder with the recording apparatus.
With the electric circuit by which the
stimulus was applied to produce contraction
were two keys, one of which was dummy.
1t was noticed that after using the active
key several times, producing varying cur
rent strengths, the curve sank as before ON
pressing down the inactive key. Since no
real effect was produced, the result was
caused solely by the imagination, blood
passing from the body to the brain in the
act. To test further the effect of
mental action, Doctor Pagliani, whose arm
was in the apparatus was requested to
multiply 267 by S, mentally, and to make
a sign when he had finished. The recorded
curve showed very distinctly how much
more blood the brain took to perform the
operation. Hence the electromagnetic is
capable of measuring the relative amount
of mental power required by different per.
sons to work out the same mental prob.
lem. Indeed, Mr.. Gaskel suggests the use
of this instrument in the examination
room, to find out, in addition to the
amount OF knowledge man possesses.
how much effort it causes him to produce
any particular result of brain. work.
Doctor Mosso relates that, while the
apparatus was set up in his room in Turin.
a classical man came in to see him. He
looked very contemptuously upon it, and
asked of what use it could be, saying that
it couldn't do anybody any good Doctor
Mosso replied: We'll, now can tell YOU
by that whether you read Greek as easily
as you can Latin As the classicist would
not believe it, his own arm was put into
the apparatus, and he was given a Latin
book to read. a very slight sinking of
the curve was the result. The Latin book
was then taken away and Greek book
was given to him. This produced immedi-
ately much deeper curve. He had as.
serted before that it was quite as easy for
him to read Greek as Latin, and that there
was no difficulty in doing either. Doctor
Mosso, however, was able to show. him
that he was laboring under delusion.
again, this apparatus is SO sensitive as
to be useful for ascertaining how much a
person is dreaming When Doctor Papli.
ami went to sleep in the apparatus. the
effect upon the resulting curve was very
marked indeed. He said afterward that
he had been in sound sleep, and remem.
bered nothing of what passed in the room
that he had been absolutely unconscious;
and yet every little movement in the room,
such as the slamming of door, the bark.
ing OF dog, and even the knocking down
of a piece Of glass, were all marked on the
curves. Sometimes he moved his lips, and
gave other evidences that he was dreaming
They were all recorded on the curve, the
amount of blood required for dreaming di-
nninishing that in the extremities.'