Fia. 46.— Fibres assooiating the cortical centres together. (Schematic, atux

Starr.)

in insensibility to optical impressions, as in inability to
understand tliem. Psychologically it is interpretable as
loss of associations between optical sensations and what
they signify; and any interruption of the paths between
the optic centres and the centres for other ideas ought to
bring it about. Thus, printed letters of the alphabet, or
words, signify both certain sounds and certain articulatory
movements. But the connection between the articulating
or auditory centres and those for sight being ruptured, we
ought a priori to expect that the sight of words wouK



■lEE FUHCTIONS OF TUB BRAIN. 113

fail to awaken the idea of their sound, or of the movement
for pronouncing them. "We ought, in short, to liave alexia,
or inability to read; and this is just what we do have as a
complication of aphasic disease in many cases of extensive'
injury about the fronto-temporal regions.

Where an object fails to be recognized by sight, it often
happens that the patient will recognize and name it as
soon as he touches it with his hand. This shows in an
interesting way how numerous are the incoming paths
whicii all end by running out of the brain through the
channel of speech. The hand-path is open, though the
eye-path be closed. When mental blindness is most com-
plete, neither sight, touch, nor sound avails to steer the
patient, and a sort of dementia which has been called asym-
bolia or apraxia is the result. The commonest articles
are not understood. The patient will put his breeches on
one shoulder and his hat upon the other, will bite into
the soap and lay liis shoes on the table, or take his food
into his hand and throw it down again, not knowing what
to do with it, etc. Such disorder can only come from
extensive brain-injury.

The centre for hearing is situated in man in the upper
convolution of the tempond lobe (see the part marked
• Wernicke' in Fig. 44). The ])]ienomena of aphasia show
this. We studied motor aphasia a few pages back; we
must !iow consider .sensory aphasia. Our knowledge of
aphasia has had three stages: we may talk of the period
of Broca, the period of Wernicke, and the period of Char-
cot. What Bro'-a's discovery Avas wo have seen. Wer-
nicke was the first to discriminate those cases in which
the patient can uof fvm iniderstand sijcech from those in
which he can understand, only not talk; and to ascribe
the former condition to lesion of the temporal lobe. The
condition in question is word-deafness, and tiio disease is
auditory aph'isio. The latest statistical survey of the
subject lA that by Dr. Alh-n Starr. In t lie seven cases
of Durc word-dcafiif-H whii li I'c has cKlii't'ti'd (cases in



114 P87CH0L0GT.

which the patie.nfc could read, talk, and "write, but not
understand what was said to him), the lesion was limited
to the first and second temporal convolutions in their
posterior two thirds. The lesion (in right-handed, i. e. left-
brained, j)ersons) is always on the left side, like the lesion
in motor aphasia. Crude hearing would not be abolished
even were the left centre for it utterly destroyed; the right
centre would still provide for that. But the linguisfic vse
of hearing appears bound up with the integrity of the left
centre more or less exclusively. Here it must be that
words heard enter into association with the things which
they represent, on the one hand, and with the movements
necessary for pronouncing them, on the other. In most
of us (as Wernicke said) speech must go on from auditory
cues; that is, our visual, tactile, and other ideas probably
do not innervate our motor centres directly, but only after
first arousing the mental sound of the words. This is the
immediate stimulus to articulation; and where the possi-
bility of this is abolished by the destruction of its usual
channel in the left temporal lobe, the articulation must
suffer. In the few cases in which the channel is abolished
with no bad effect on speech we must suppose an idiosyn-
crasy. The patient must innervate his speech-organs either
from the corresponding portion of the other hemisphere
or directly from the centres of vision, touch, etc., without
leaning on the auditory region. It is the minuter analysis
of such individual differences as these which constitutes
Charcot's contribution towards clearing up the subject.

Every namable thing has numerous properties, qualities,
or aspects. In our minds the properties together with the
name form an associated group. If different parts of the
brain are severally concerned with the several properties,
and a farther part with the hearing, and still another
with the uttering, of the name, there must inevitably be
brought about (through the law of association which we
shall later study) such a connection amongst all these brain-
parts that the activity of any one of them will be likely t/



THE FUXCTIONS OF THE BRAIN. 115

awaken the activity of all the rest. When we are talking
whilst we tliiiik, the ultimate process is utterance. If the
brain-part for that be injured, speech is impossible or dis-
orderly, even though all tlie other brain-parts be intact:
and this is just the condition of things which, on p. 109,
we found to be brought about by lesion of tlie convolution
of Broca. But back of that last act various orders of suc-
cession are possible in the associations of a talking man's
ideas. The more usual order is, as aforesaid, from the tac-
tile, visual, or other properties of the things thought-about
to tlie sound of their names, and then to the hitter's utter-
ince. But if in a certain individual's mind the look of an
object or the look of its name be wliat habitually precedes
articulation, then the loss of the Iwaring centre will pro
Utnto not affect that individual's speech or reading. He
^■ill be mentally deaf, i.e. his nnderstandiug of the human
.'oice will suffer, but he will not be aphasic. In this way
•t is possible to explain the seven cases of word-deafness
without motor aphasia which figure in Dr. Starr's table.

If tliis order of a.^.sociation be ingrained and habitual in
that individual, injury to his visual centres will nuike him
not only word-blind, but aphasic as well. Ilis speech will
become confused in consequence of an occipital lesion.
?saunyn, consequently, plotting out on a diagram of the
hemisphere the 71 irreproachably reported cases of aphasia
which he was able to collect, finds tluit the lesions concen-
trate themselves in three places: first, on Broca's centre;
second, on "Wernicke's; third, on the supra-marginal and
angular convolutions under which those fibres pass which
connect the visual centres with the rest of the brain (see
Fig. 47, p. 1 1'i). With this result Dr. Starr's analysis of
[)urely sensory cases agrees.

In the chapter on Imagination wi' shall return to thi-se
(iifTfrcncfS in the sensory sjdieres of different individuals.
.Meanwhile few things show more beautifully than the his-
torv <»f our knowledge of aphasia how the sagacity and
Datience of irianv banded workers are in time certain to



116



FSrCHOLOOr.



analyze the darkest confusion into an orderly displa}!
There is no ' organ ' of Speech in the brain any more than
there is a 'faculty' of Speech in the mind. The entire
mind and the entire brain are more or less at work in a




Fia. 47.



man who uses language. The subjoined diagram, from
Ross, shows the four parts most vitally concerned, and,
in the light of our text, needs no farther explanation (see
Fig. 48, p. 117).

Centres for Smell, Taste, and Touch. — The other sensory
centres are less definitely made out. Of smell and taste I
will say nothing; and of muscular and cutaneous feeling
only this, that it seems most probably seated in the motor
zone, and possibly in the convolutions immediately back-
wards and midwards thereof. The incoming tactile cur-
rents must enter the cells of this region by one set of fibres,
and the discharges leave them by another, but of these
refinements of anatomy we at present know nothing.



THE FUJSOTIOJS'S OF THE BRAIN.



117



Conclusion. — We thus see the postuhite of Meynert and
Jackson, witli which we started on p. 105, to be on the whole
most satisfactorily corroborated by objective research. The
hiyhest centres do prubublij contain nothing bat arrange'




Fio. 48.— i4 1b the auditory centre, V the vtmial, H^ the writing, and JSthat for

speech.

mentn for representing imprenxions and movements, and
other arrangements for coupling the activity of these ar-
rangements together. Currents "ponriii}^ in from tlie seiise-
orjrans first excitf- some arran^^'cnicuts, which in turn ext-ito
others, until at last a dischar;;e downwards of some sort
occurs. When this is on(;e clearly grsisped there remains
little ground forjisking whether the motor zone is exclusively
motor, or sensitive as well. The wIk.U; cortex, inasmuch ;u-'



118 PSYCHOLOGY.

currents run through it, is both. All the currents probably
have feelings going with them, and sooner or later bring
movements about. In one aspect, then, every centre is affer-
ent, in another efferent,even the motor cells of the spinal cord
having these two aspects inseparably conjoined. Marique,
and Exner and Paneth have shown that by cutting round
a ' motor ' centre and so separating it from the influence of
the rest of the cortex, the same disorders are produced as
by cutting it out, so that it is really just what I called it,
only the funnel through which the stream of innervation,
starting from elsewhere, escapes; consciousness accompany-
ing the stream, and being mainly of things seen if the
stream is strongest occijntally, of things heard if it i&
strongest temporally, of things felt, etc., if the stream occu-
pies most intensely the 'motor zone.' It seems to me that
some broad and vague formulation like this is as much as
we can safely venture on in the present state of science—
60 much at least is not likely to be overturned. But it is
obvious how little this tells us of the detail of what goes
on in the brain when a certain thought is before the mind.
The general forms of relation perceived between things, as
their identities, likenesses, or contrasts; the forms of the
consciousness itself, as effortless or perplexed, attentive or
inattentive, pleasant or disagreeable; the phenomena o5
interest and selection, etc., etc., are all lumped together ai
effects correlated with the currents that connect one centrt
with another. Nothing can be more vague than such a
formula. Moreover certain portions of the brain, as the
lower frontal lobes, escape formulation altogether. Their
destruction gives rise to no local trouble of either motion
or sensibility in dogs, and in monkeys neither stimulation
nor excision of these lobes produces any symptoms what-
ever. One monkey of Horsley and Schaefer's was as tame,
and did certain tricks as well, after as before the operation.
It is in short obvious that our knowledge of our mental
states infinitely exceeds our knowledge of their concomi-
tant cerebral conditions. Without introspective analysis of



THE FUNCTIONS OF THE BRAIN. 119

the mental elements of speech, the doctrine of Aphasia, for
instance, which is the most brilliant jewel in Physiology,
would have been utterly impossible. Our assumption,
therefore (p. 5), that mind-states are absolutely dependent
on brain-conditions, must still be understood as a mere
postulate. We may have a general faith that it must be
true, but any exact insight as to how it is true lags wofully
behind.

Before taking up the study of conscious states prop-
erly so called, I will in a separate chapter speak of two or
three aspects of brain-function which have a general im-
portance and which cooperate iu the production of all our
mental states.



CHAPTER IX.

SOME GENERAL CONDITIONS OF NEURAL ACTIVITY,

The Nervous Discharge. — The word discharge is con-
stantly used, and must be used in this book, to designate
the escape of a current downwards into muscles or other
internal organs. The reader must not understand the
word figuratively. From the point of view of dynamics
the passage of a current out of a motor cell is probably
altogether analogous to the explosion of a gun. The mat-
ter of the cell is in a state of internal tension, which the
incoming current resolves, tumbling the molecules into a
more stable equilibrium and liberating an amount of
energy which starts the current of the outgoing fibre.
This current is stronger than that of the incoming fibre.
When it reaches the muscle it produces an analogous dis-
integration of pent-up molecules and the result is a stronger
effect still. Matteuci found that the work done by a mus-
cle's contraction was 27,000 times greater than that done
by the galvanic current which stimulated its motor nerve.
When a frog's leg-muscle is made to contract, first directly,
by stimulation of its motor nerve, and second reflexly, by
stimulation of a sensory nerve, it is found that the reflex
way requires a stronger current and is more tardy, but
that the contraction is stronger when it does occur. These
facts prove that the cells in the spinal cord through which
the reflex takes place offer a resistance which has first lo
be overcome, but that a relatively violent outward current
outwards then escapes from them. What is this but an
explosive discharge on a minute scale ?

Reaction-time. — The measurement of the time required
for the discharge is one of the lines of experimental iuves'



GENERAL CONDITIONS OF NEURAL ACTIVITY. 121

tigatioii most diligently followed of lute years. Helmholtz
led the way by discovering the rapidity of the outgoing
current in the sciatic nerve of the frog. The methods
he used were soon applied to sensory reactions, and the
results caused much popular admiration when described as
measurements of the ' velocity of thought.' The phrase
* quick as thought ' had from time immemorial signified all
that was wonderful and elusive of determination in the line
of speed ; and the way in Avhich Science laid her doomful
hand upon this mystery reminded people of the day when
Franklin first ' eripuit coelo fiilmen' foreshadowing the
reign of a newer and colder race of gods. I may say, how-
ever, immediately, that the phrase 'velocity of thought' is
misleading, for it is by no means clear in any of the cases
■wliat particular act of thought occurs during the time
which is measured. What the times in question really
represent is the total duration of certain reactions upon
stimuli. Certain of the conditions of the reaction are
prepared beforehand; they consist in the assumption of
those motor and sensory tensions which we name the ex-
pectant state. Just what happens during the actual time
occujiied by the reaction (in other words, just what is
added to the pretixistent tensions to produce tlio actual
discharge) is not made out at present, either from the
neural or from the mental point of view.

The method is essentially the same in all these investiga-
tions. A sigTuil of some sort is communicated to the sub-
ject, and at the same instant records itself on a time-regis-
tering apparatus. The 6u])ject then makes a muscular
movement of some sort, which is the 'reaction,' and which
also records itself automatically. The time found to liave
elapsed between the two records is the total time of that
rea<;tion. 'J'he time-registering instruments arc of various
types. One type is that of the revolving drum covered
with smoked j)aper, on which one electric pen traces a line
whicli the sigiuil breaks and the 'reaction' draws again;
wliilst another electric pen (connected with a rod of metul



122



P8YCH0L0OY.



\


t '


'








\AA/^/\AAAAAAAAAAA/\AAAAA/^



vibrating at a known rate) traces alongside of the former
line a ' time-line ' of which each undulation or link stands
for a certain fraction of a second, and against which the
break in the reaction-line can be measured. Compare Fig.
49, where the line is broken by the signal at the first

SignaL Reaction



Reaction-line.
Time-line.



Fig. 49.

arrow, and continued again by the reaction at the second.
The machine most often used is Hipp's chronoscopic clock.
The hands are placed at zero, the signal starts them (by
an electric connection), and the reaction stops them. The
duration of their movement, down to lOOOths of a second,
is then read oif from the dial-plates.

Simple Reactions. — It is found that the reaction-time
diifers in the same person according to the direction of his
expectant attention. If he thinks as little as possible of
the movement which he is to make, and concentrates his
mind upon the signal to be received, it is longer; if, on the
contrary, he bends his mind exclusively upon the muscu-
lar response, it is shorter. Lange, who first noticed this
fact when working in Wundt's laboratory, found his own
'muscular' reaction-time to average 0'M23, whilst his
'sensorial' reaction-time averaged as much as 0".230. It is
obvious that experiments, to have any comparative value,
must always be made according to the 'muscular' method,
which reduces the figure to its minimum and makes it
more constant. In general it lies between one and two
tenths of a second. It seems to me that under these cir-
cumstances the reaction is essentially a reflex act. The
preliminary making-ready of the muscles for the move-



GENERAL CONDITIONS OF NEURAL ACTIVITY. 123

ment means the excitement of the paths of discliarge to
a point just short of actual discliarge before the signal
conies in. In other words, it means the temporary forma-
tion of a real * reflex-arc ' in the centres, through which
the incoming current instantly can pour out again. But
when, on the other hand, the expectant attention is exclu-
sively addressed to the signal, the excitement of the motor
tracts can only begin after this latter has come in, and
under tliis condition the reaction takes more time. In
the hair-trigger condition in which we stand when making
reactions by the ' muscular ' method, we sometimes respond
to a wrong signal, especially if it be of the same kind with
the one we expect. The signal is but the spark which
touches off a train already laid. There is no thought in
the matter; the hand jerks by an involuntary start.

These experiments are thus in no sense measurements of
the swiftness of thought. Only when we complicate them
is there a chance for anything like an intellectual operation
to occur. They may be complicated in various ways. The
reaction may be withheld until the signal has consciously
awakened a distinct idea (Wundt's discrimination-time, asso-
ciation-time), and may then be performed. Or there may be
a variety of possible signals, each with a different reaction
assigned to it, and the reacter may be uncertain which one
he is about to receive. The reaction would then hardly
seem to occur without a preliminary recognition and choice.
Even here, however, the discrimination and choice are
widely different from the intellectual operations of which
we are ordinarily conscious under those names. Alean-
wbile the simple reaction-time remains as the starting
point of all these superinduced complications, and its own
variati(jns must be ]>riefly passed in review.

The reat;tion-time varies with the individ lal and his
age. Old and uncultivated peojde have it long (nearly a
second, in an nM paujier observed by Exner). Children
have it long (half a second, according to Ilerzeii).

Practice shortens it to a fiiiantity whicli is for eacii indi-



124 P8FCH0L0O7.

vidual a minimum beyond which no farther reduction can
be made. The aforesaid old pauper's time was, after much
practice, reduced to 0.1866 sec.

Fatigue lengthens it, and concentration of attetition
shortens it. The nature of the signal makes it vary. I
here bring together the averages which have been obtained
by some observers:

Hirsch. Hankel. Exner. Wundt.

Sound 0.149 0.1505 0.1360 0.167

Light 0.200 0.2246 0.1506 0.222

Touch 0.183 0.1546 0.1337 0.213

It will be observed that sound is more promptly reacted
pn than either sight or touch. Taste and smell are slower
than either. The intensity of the signal makes a differ-
ence. The intenser the stimulus the shorter the time.
Herzen compared the reaction from a corn on the toe with
that from the skin of the hand of the same subject. The
two places were stimulated simultaneously, and the subject
tried to react simultaneously with both hand and foot, but
the foot always went quickest. A¥hen the sound skin of
the foot was touched instead of the corn, it was the hand
which always reacted first. Intoxicants on the whole
lengthen the time, but much depends on the dose.

Complicated Reactions. — These occur when some kind
of intellectual operation accompanies the reaction. The
rational place in which to report of them would be under
the head of the various intellectual operations concerned.
But certain persons prefer to see all these measurements
bunched together regardless of context; so, to meet their
views, I give the complicated reactions here.

When we have to think before reacting it is obvious that
there is no definite reaction-time of which we can talk — it
all depends on how long we think. The only times we
can measure are the minimum times of certain determinate
and very simple intellectual operations. The time required
for discrimination has thus been made a subject of experi-
mental measurement. Wundt calls it UnterscheiduH(jszeit.



GK^ERAL COXDITIONS OF NEURAL ACTIl'ITT. 125

His subjects (whose simple reaction-time had previously
been determined) were required to make a movement,
alwavs the same, the instant they discerned which of two
or more signals tliey received. The exce.s.s of time occupied
by these reactions over the simple reaction-time, in which
ouly one signal was used and known in advance, measured,
according to Wundt, the time required for the act of dis-
crimination. It was found longer when four different
signals were irregularly used than when only two were
used. When two were used (the signals being the sudden
appearance of a black or of a white object), the average
times of three observers were respectively (in seconds)
0.050 0.04: 0.079
AVhen four signals were used, a red and a green light
being added to the others, it became, for the same observers,
0.157 0.073 0.132
Prof. Cattell found he could get no results by this
method, and reverted to one used by observers previous to
AVundt and which Wundt had rejected. This is the
einfache Wahlmcthode, as Wundt calls it. The reacter
awaits the signal and reacts if it is of one sort, but omits
to act if it is of another sort. The reaction thus occurs
after discrimination; the motor impulse cannot be sent
to the hand until the subject knows what the signal is.
Reacting in this way, Prof. Cattell found the increment of
time required for distinguishing a white signal from no
signal to be, in two observers,

0.030 and 0.050;
that fur dirftiuguisliing one color from another was simi-
larly

0.100 and 0.110;
that for distinguishing a certain color from ten other
colors,

0.105 and 0.117;
that for diritinguishiiig tlio letter A in ordinary ])rint from
the letter Z,

0.142 and 0.137;



126 PSTCHOLOO 7.

that for distinguishing a given letter from all the rest of
the alphabet (not reacting until that letter appeared),

0.119 and 0.116;
that for distinguishing a word from any of twenty-five
other words, from

0.118 to 0.158 sec.

— the difference depending on the length of the words and
the familiarity of the language to which they belonged.

Prof. Cattell calls attention to the fact that the time for
distinguishing a word is often but little more than that for
distinguishing a letter : " We do not, therefore," he says,
" distinguish separately the letters of which a word is com-
posed, but the word as a whole. The application of this in
teaching children to read is evident."

He also finds a great difference in the time with which
various letters are distinguished, E being particularly bad.

Tlie time required for association of one idea with
another has been measured. Galton, using a very simple
apparatus, found that the sight of an unforeseen word
would awaken an associated ' idea ' in about f of a second.
Wundt next made determinations in which the ' cue ' wa;.
given by single-syllabled words called out by an assistant.
The person experimented on had to press a key as soon as
the sound of the word awakened an associated idea. Both