24
E. IV. Scripturei
The next step was to eliminate the effect of strain on the finger. This
was done by having the subject always react with a key of no tension ;
the telegraph key was used in order not to introduce any further change. •
The finger necessarily remained passive, as the key responded to the
slightest movement. The subject reacted in alternate sets with two de¬
grees of voluntary effort. The degrees were defined as “light” and
“strong; ” the intention was to make the effort correspond somewhat to
the extremes of o and the heaviest weight in the previous set, but no
measurements were made on the actual energy of effort.
The results are given in Table V.
Table V.
Subject.
1 ,ight effort.
Strong effort.
R
d n
R
d n
D
Holden
l5S
IO 26
143
8 27
15
Scripture
179
16 17
154
19 18
25
Seashore
168
15 9
137
21 6
31
Fisher
626
25 S
375
4t 6
241
Unit, thousandth of a second. «, number of measurements.
R, reaction-time. D, decrease in R for strong as compared
d, mean variation. j with light effort.
The figures for the colored janitor, Fisher, are interesting. Having
been accustomed for several years to serve as subject in exercises and in¬
vestigations, he is perfectly at home in the work and yet has no interest
or concern in the experiment beyond carrying out the instructions ; these
facts make his record very reliable. His unusually long reaction-time
has been observed for several years.
The problem has thus found a definite solution : the intensity of the
effort affects the reaction-time, making it shorter for the greater intensity.
Simple and cortical reaction-time.
(Howard F. Smith, M.D.)
The determination of the time of a motor response to a direct stimu¬
lation of the cerebal cortex and a comparison of this time with the sim¬
ple reaction-time of the subject would apparently lead to certain con¬
clusions concerning the relation between mental and cerebral processes.
The attempt has been made in the following manner. .
A cat was held quietly in the hands of an assistant. A double pointed
platinum electrode was rested against the skin at a suitable point. A