The Principles of Psychology, Volume 1 (of 2)James, William
Philosophy
The Principles of Psychology, Volume 1 (of 2)
James, William
Psychology
[115] In short, what M. Delbœuf calls an '_organe adventice_.' The
reaction-time, moreover, is quite compatible with the reaction itself
being of a reflex order. Some reflexes (sneezing, e.g.) are very slow.
The only time-measurement of a reflex act in the human subject with
which I am acquainted is Exner's measurement of winking (in Pflüger's
Archiv f. d. gesammt. Physiol., Bd. viii, p. 526, 1874). He found that
when the stimulus was a flash of light it took the wink 0.2168 sec.
to occur. A strong electric shock to the cornea shortened the time
to 0.0578 sec. The ordinary 'reaction-time' is midway between these
values. Exner 'reduces' his times by eliminating the physiological
process of conduction. His 'reduced minimum winking-time' is then
0.0471 (_ibid._ 531), whilst his reduced reaction-time is 0.0828
(_ibid._ vii, 637). These figures have really no scientific value
beyond that of showing, according to Exner's own belief (vii, 531),
that reaction-time and reflex-time measure processes of essentially
the same order. His description, moreover, of the process is an
excellent description of a reflex act. "Every one," says he, "who
makes reaction-time experiments for the first time is surprised to
find how little he is master of his own movements, so soon as it
becomes a question of executing them with a maximum of speed. Not only
does their energy lie, as it were, outside the field of choice, but
even the time in which the movement occurs depends only partly upon
ourselves. We jerk our arm, and we can afterwards tell with astonishing
precision whether we have jerked it quicker or slower than another
time, although we have no power to jerk it exactly at the wished-for
moment."--Wundt himself admits that when we await a strong signal
with tense preparation there is no consciousness of any duality of
'apperception' and motor response; the two are continuous (Physiol.
Psych., ii, 226).--Mr. Cattell's view is identical with the one I
defend. "I think," he says, "that if the processes of perception and
willing are present at all they are very rudimentary.... The subject,
by a voluntary effort [before the signal comes], puts the lines of
communication between the centre for" the stimulus "and the centre for
the co-ordination of motions ... in a state of unstable equilibrium.
When, therefore, a nervous impulse reaches the" former centre, "it
causes brain-changes in two directions; an impulse moves along to
the cortex and calls forth there a perception corresponding to the
stimulus, while at the same time an impulse follows a line of small
resistance to the centre for the co-ordination of motions, and the
proper nervous impulse, already prepared and waiting for the signal,
is sent from the centre to the muscle of the hand. When the reaction
has often been made the entire cerebral process becomes automatic, the
impulse of itself takes the well-travelled way to the motor centre, and
releases the motor impulse." (Mind, xi, 232-3.)--Finally, Prof. Lipps
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