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at al approached by the instruments of this science.
Emotions, volitions, and all intellectual processes are
obviously beyond the reach of any form of quantitative
me surement. Even, then, if psycho-physics had
attained the utmost hopes of its supporters, and if
— what appears equall}^ unlikely — these supporters
became agreed as to their results, our knowledge of
mental life would not really be thereby much advanced.

3. Again, there may be raised an objection against

11 Unfortunately the figures given by different observers vary.

'- Cf Ladd, ihld. pp. 361, 362; Lotze, MdapJiysic, §§ 25S, 259;
James, ibid. p. 54G. On the other side, cf Wundt, Hiiiuan and
Animal Psycholvvy (Eng. Trans.), pp. 20— Co.



58 SENSUOUS LIFE.



the conclusions of psychophysicists even within the re-
stricted sphere of sensational consciousness, an objection
which strikes at the possibility of any kind of quanti-
tative estimate of mental phenomena. An assumption,
involved in all Fechner's experiments, and lying at the
root of his chief psychological law, implies that while
sensation increases in quantity or intensity, the quality
remains unaffected. A locomotive of twenty-horse
power can drag a load twice as heavy as an engine
of ten-horse power. The force exerted in such a case
may be rightly described as double in quantity yet
similar in quality. But we can hardly say this as
regards the energies of mental life. Sensations of light,
sound, temperature, and the rest, increased in intensity,
do not appear to preserve the same (pality of con-
sciousness. The transition from black to white, from
hot to cold, from the trickling of the fountain to the
roar of the waterfall, is not merely a variation in
quantity. In small increments, the alteration in
quality may escape notice, but when the effects of
large changes in the degree of the stimulus are
compared, introspection seems to affirm changes of
quality as well as of quantity.

4. Finally, these difficulties are reinforced by serious
attacks from careful observers, who question the truth
of the alleged results on the evidence of direct experi-
ence. Thus, Hering, for example, rejects the Weber-
Fechner generalization on the grounds, (a) that admit-
tedly its application has to be limited to a very narrow-
range above and below normal stimulation, and {b) that
it is completely " inapplicable either to taste or smell,
to heat, to weight, or to sound, and that therefore it
has not the character of a general law of sensibility."^-^

Interpretation of the Weber-Fechner Law. — Why, it may

be asked, does the sensation increase more slowly than its

'^ Ribot, La PsycJwlope AUcmandc, p. ig6. Chapter v. of that
work contains a good reaumc of the subject. See also, Ladd's
Physiological r.\YcJio!of;y, I't. II. c. v. The reader of that chapter will
notice how much disagreement prevails regarding the figures. Of
scholastic writers on this subject, see Gutberlet, Die Psychologic,
pp 34—41 ; Mercier, Psychologic, pp. 148 — 154; Farges, L^ Cerveaii
et I'Aine, pp. 209—226.



SENSATION. 59



objective excitant ? Fechner answers that his f,'enerah;cation
is an ultimate law describing the relation between physical
stimuli and ps3xhical reaction, or between body and soul.
The intensity of the nervous change transmitted to the brain
increases, he supposes, in direct proportion to the physical
stimulus, but the sensation only in proportion to the logarithm
of the latter. It must, therefore, be conceived as an ultimate
psycho-physical law for which no further explanation can be
demanded.

Others give 2i physiological interpretation to the generaliza-
tion of the facts in so far as this holds good. It is, they
assert, not an ultimate expression of the relation betweeia
mental and material action, but a law describing the relations
between the external physical stimulus and the nervous
action which reaches the brain. The conscious reaction in
this view increases in direct proportion to the intensity of the
final physiological stimulus, but the latter increases more
slowly than the physical stimulus, owing to the augmentation
of resistance and friction as the sphere of nervous disturbance
becomes larger.

Finally, others seek to explain the law psychologically,
maintaining that it expresses neither the relation between the
physical and the psychical change, nor between the former
and physiological action, but between the sensations and our
powers of discriminating them. All appreciation, according
to these writers, is relative to existing states. The differences
between mental states have their value determined by their
relation to these states, diminishing in proportion to the
intensity of the latter. ^^

Whilst the reality of the law is subject to such serious
dispute, speculation as to its interpretation appears to us
neither very hopeful nor profitable, but the physiological
explanation seems to give a sufficient account of the facts.

Psychometry : Reaction-time. — If a harpoon be
stuck in the tail of a whale an appreciable interval
elapses before the tail is moved. The impression, in
fact, requires time to be transmitted along an affcvent
nerve to the whale's brain before the whale becomes
conscious of the pain, and another period is needed for
the transmission of an impulse back from the brain
along a motov nerve to set the tail in motion. The
whole interval is called reaction-time.

A similar phenomenon is observed in the case of

" Cf. Wundt, i}}id. pp. 59—64.



6o SENSUOUS LIFE.



human beings in regard to impressions on the several
senses. In recent years ingenious psycho-metrical
instruments have been invented, and a great number
of elaborate experiments have been made to determine
accurately the reaciioii-time with respect to different kinds
of sensation. The general plan pervading the various
methods of expermient is the stimulation of some sense-
organ to v.-hich the subject responds by a sign the
instant he apprehends the sensation. ^'^ The experiment
can be varied so as to involve simpler or more complex
operations. Thus the subject, who is blindfolded, is
asked to press an electric button as soon as he feels a
tap on either knee, whilst a finely graduated time-
keeper measures, to the one-hundredth part of a second,
the interval between the tap and the signal. Next he
is asked to press the button only when the right knee is
tapped, remaining quiet if the left is touched ; or he is
requested to signal with the other hand if he feels the
sensation in his left leg. The act of choice here intro-
duced considerably lengthens the process. Similar
experiments are made in regard to the time occupied in
apprehending and discriminating various sensations of
colour, sor.nd, taste, and smell.

Tlie entire process between the impression and the
motor sign has been analyzed into several stages,
amongst vh'ch the following may be easily distin-
guished:^^ (i) The excitation of the end-organ of the
sense sufficiently to start the neural change. (2) The
conduction of this neural change along the centripetal
or afferent nerves to the brain. (3) The transformation
of the sensory impression into the motor impulse.
(4) The transmission of this motor change back along
efferent nerves to the appropriate muscle. (5) The
excitation and contraction of this muscle in the signalling
action.

Of tliesc stages only the third is a psycho-ph3sical
event. All the others are physiological, and as their
duration can be approximately determined by various

^^ A full description and numerous illustrations of these various
psycho-niclv'-'i] machines are given by E. Scripture, op. cit.
^ '^ Cf. I dJ '>p. cit. p. 470; James, op. cit. p. 88.



SEMSA TtON. 6t



experiments and then climinatccl, the lengtli of the
strictly psycho-physical portion of the whole reaction,
it is alleged, may be estimated.

Wundt gives as average total reaction-time of a
series of experiments, for impressions of sound, 0-128 of
a second; for light, 0*175; for touch sensations, o-i88.
But Exner, Hirsch, and others give different figures.
Study of these investigations goes to prove that the
reaction-time varies much with different individuals.
On this fact is based the "personal equation" of
different observers which have to be taken into account
in certain delicate astronomical observations. Further,
it seems clear that practice shortens the reaction-time
very considerably, and that expectant attention also
diminishes it. On the other hand, fatigue increases it ;
intensity of stimulus, too, causes a difference ; the
v/eather, the general health of the individual, and the
nature of the stimulus also modify the rapidity of
the reaction.

Many writers exhibit a laudable enthusiasm for this
new department of investigation. We confess, however,
we cannot share in their hopeful expectations of psycho-
logically valuable future results; nor does the character
of those yet reached justif}^ the very roseate anticipations
entertained. For these experiments after all furnish
physiological rather than psychological information. They
measure the speed or intensity of nervous processes
with which certain mental operations may, or may not,
be concomitant ; but they throw no real light on the
quality of these latter. They are in no true sense a record
of the rapidity of thought, and if employed as a means of
measuring intelligence or mental development, they are
utterly misleading. They may indeed help to indicate
the delicacy or discriminative sensibility of the sense-
organs and nervous system, but the extent to which the
reaction-time can be shortened by a little practice and
other slight alterations of tlie conditions proves what
a ver}^ insecure standard it would be even in this
respect.^''

^■^ Mr. Sully writes: "Those researches show that mental
capacity in general grows between the age of six and seventeen — at



62 SENSUOUS LIFE.



Readings. — On the physiology of the nervous system, see any of
the elementary text-books of Physiology. Carpenter's Mental Physio-
logy, c. ii., and R. S. Wyld's Physics and Physiology of the Senses,
Pt. IV. treat the subject well, with special reference to Psychology.
However, by far the best and most exhaustive work on the physio-
logical conditions of mental life, which has yet appeared in English,
is Professor Ladd's Elements of Physiological Psychology. The German
reader will find an able and interesting treatment of the whole
subject of sensation by Gutberlet, Die Psychologic, pp. 12—48. On the
history of the terms sensation and perception, cf. Hamilton, Meta-
physics, Vol. II. pp. 93 — 97, and Notes and Dissertations on Reid, Note
D. The subject of species is treated in all the Latin manuals ;
perhaps, Sanseverino's Dynamilogia, pp. 373 — 403, is amongst the
best. Suarez, De Anima, Lib. III. cc. 2, 3, discusses the matter at
length. See also J. Rickaby, First Principles, pp. 8, seq. An admir-
able exposition of the Scholastic doctrine of intellectual knowledge
by means of specks is contained in Kleutgen's Philosophic der Vorzeit,
U 18-52.

first quickly, then more slowly, &c." [Teachers' Handbook of Psychology,
p. 94, 4th Edit. ; cf. Scripture, loc. cit. pp. 134, 169.) The value of
such experixnents as a standard of " mental capacity " is evinced by
the fact that the reaction-time of a pauper, aged 77, experimented
on by Exner, was reduced by a little practice from 0-9952 to o 1866
of a second ! The explanation is simple enough. The " mental
capacity " of the old man was pretty much the same at the end as
at the beginning of the experiments, but his nervous apparatus had
acquired the " knack " or facility of reacting in less than one fifth
of the original time. Similarly, children may exhibit varying
aptitudes, inherited or acquired, in regard to such operations, as
they may vary in their power of acquiring any ordinary reflex-
action, with little or no relation to their intellectual ability. On
the whole subject, cf. James, Vol. I. c. iii. and Ladd, Part II.
c. viii.



CHAPTER V.

THE SENSES.

How many External Senses ? — A group ci
sensations containing a number of features in
common are assigned, we have said, to a special
sense. The question may now be raised, how many
senses have we ? There has been a good deal of
disagreement on the point among modern writers,
but the decision arrived at does not seem to us to
be of very much importance, provided that the
various forms of sensibility be recognized. The
specialization of the organ, the nature of the
stimulus, and the quality of the consciousness, have
each been advocated as the true principle of classi-
fication, and different plans have consequently been
drawn up.^ In favour of the old-fashioned scheme

^ Following Kant, Hamilton styles the five special senses the
sensus fixus, and adds to them a sixth general sense, the sensiis vagus,
common feeling, the vital sense, or aen^Fstiesis, embracing the feelings
of temperature, shuddering, health, muscular tension, hunger, and
thirst, &c. Dr. Bain's scheme stands thus: a. Muscular sense.
B. Six classes of organic sensations: (i) of muscle, (2) of nerve,
(3) of circulation and nutrition, (4) of respiration, (5) of temperature,
(6) of electricity, c. The five special senses. G. H. Lewes empha-
sized the importance of the systemic sensations, e.g., feelings of
digestion, respiration, temperature, circulation, &c. Mr. Murray,
who adheres consistently to distinction of organ as his principle
of division, gives this classification : I. The Five Special Senses.
II. General Senses, a. Connected with a single organ: (i) muscular



64 SENSUOUS LIFE.



of the five senses, taste, smell, hearing, sight, and
touch, it may be urged that it recognizes the obvious
structural differences of organ, to a great extent the
most marked differences in the quahty of the con-
sciousness, and also generic differences in the
phenomena apprehended. The eye reveals to us
colours, the ear sound, the nose smell, the tongue
taste, and touch pressure. In the language of the
schools, the formal objects of the several senses are
generically different. However, if this classification
be adopted, it must be remembered that under the
sense of touch are comprised many groups of mental
states importantly different in quality, and frequently
attached to parts of the organism of very specialized
character.

Method of Exposition. — The most convenient
order of procedure will be to start from the simpler
and more easily described faculties, and to go on
gradually to those of a higher, more varied and
complex nature. In our exposition we will adopt
the usual plan of saying a few words on the formal
obj-ect of each sense, on the physiological machinery
employed, and on the character of the consciousness
awakened. In dealing v/ith this last phenomenon,
which is the proper subject-matter of Psycholog}',

sensations, (2) pulmonary sensations, (3) alimentary sensations.
B. General sensations not confined to a single organ: (i) of tem-
perature, (2) of organic injuries, &c., (3) of electricity. The true
principle, however, if it could be satisfactorily applied, would be
the quality of consciousness. Differentiation of organ is an extrinsic
physiological consideration. Still the difficulty of determining how
much qual'.tative difference justifies the assumption of a special
s'.ose renders the former princiyli of little value once we depart
from th.e old scheme oi five senses.



THE SENSES. 65



the two chief features to be attended to are what
have been styled the emotional and the intellectual
aspects of the sense. By the former is meant, the
susceptibiHty of the faculty to pleasure or pain ; by
the latter, its efficiency as an instrument of know-
ledge of the external world. The use of the epithet
*' intellectual," however, is very inaccurate here,
and still more so when applied to individual sensa-
tions. The Intellect is a faculty essentially distinct
from sensuous powers, and its activity, just as that
of any of the senses, may possess a pleasurable or
painful character. It will accordingly be more
appropriate to term this property of a sense or
sensation its cognitional aspect.

Taste. — Physiological conditions. — The formal
object of the sense of taste is that quality in certain
soluble substances in virtue of which they are called
sapid. The organ of taste is the surface of the
tongue and palate. Over these surfaces are dis-
tributed the gustative papillce, from which nerves
proceed to the brain. In order to excite the sensa-
tion, the body to be tasted must be in a state of
solution in the mouth. The precise nature of the
action of the sapid substance on the papillae is
unknown, but it is probably chemical.

Sensations. — The sensations of this faculty do not
possess such definite qualitative differences as to
fall into well-determined groups, and consequently
there is no general agreement in the classification
of different tastes. The proper pleasure of the
sense is sweetness; its proper pain bitterness. Most

F



66 SENSUOUS LIFE.



gustatory sensations involve elements of tactual,
nasal, and organic feelings. Thus, acid, alkaline,
fiery, and astringent tastes, are in part the effects
of tactual stimulation ; feelings of relish and disgust
are traceable to the sympathy of the alimentary
canal ; and sensations of smell also influence our
estimation of the sapid qualities of many substances.
The cognitional value of this sense is very low. Con-
tinuous stimulation rapidly deadens its sensibility ;
its recuperative power is tardy, its sensations are
wanting in precision, and they can be but very
imperfectly revived in imagination. The main
grounds of its cognitive inferiority, however, lie in
its essentially subjective character. Abstracting
from the information afforded by concomitant
tactual sensations, taste originally gives us no
knowledge of external reality, and, consequently,
with the exception of the vague systemic feelings
of the organism, it must be ranked lowest as a
medium of communication with the physical world.
On the other hand, viewed from the standpoint
of feeling, this sense is capable of intense but short-
lived pleasure and pain. Though the lowest of our
faculties in point of refinement, and the most subject
to abuse, its great utility as a guide in the selection
of food throughout the animal kingdom is evident.

Smell. — Physiological conditions. — Odorous par-
ticles emitted from gaseous or volatile substances
constitute the appropriate stimulus of this sense.
The organ of smell is the cutaneous membrane
lining the inner surface of the nose. The action of



THE SENSES. 67



the odorous substance is probably of a chemical
character, and the simultaneous inhaling of the air
is requisite for the production of the sensation. In
the act of inhalation the stimulating particles are
drawn through the nostrils over the sensitive
surface. Even the strongest smelling substances
are not perceived as long as we hold our breath.

Sensations. — This sense resembles that of taste
in many respects. Vagueness is a marked feature
of each; continuous excitation renders both obtuse;
their recuperative power on the cessation of the
stimulus is weak; and both are originally of a like
subjective character. The close affinity of the two
faculties is exhibited in the difficulty of determining
how far the recognition of a particular substance is
due to taste, and how far to smell ; and in the
readiness with which most of the adjectives, such
as sweet, bitter, pungent, primarily qualifying
sensations of taste, are transferred to those of
smell. The attempt to distinguish port wine from
sherry, apart from sight and smell, is a familiar
method of illustrating the former. The delicate
susceptibility of smell to some kinds of stimulation
is, however, very surprising. The merest trace of
a drop of oil of roses awakes a pleasurable feeling,
and as infinitesimal a particle as the one thirty-
millionth part of a grain of musk is perceptible.
The delicacy of this faculty in the dog and other
brute animals,- as is well known, far exceeds what

- Cf. Bernstein, The Five Senses, p. 290. He says that some
animals can, when the wind is favourable, scent the huntsman
several miles away. The number and the minuteness of the volatile
particles which proceed from objects perceivable at such distances
pass comprehension.



68 SENSUOUS LIFE.



it attains in man. Just as in the case of taste, the
sensations of smell may be of an extremely agree-
able or disagreeable character. They stand higher,
however, in order of refinement. They are, too,
more easily revived in imagination ; and, being
awakened by objects at a distance, these sensations,
like those of sight, assume the character of pre-
monitory signs of other future experiences. In this
way the sense of smell comes to surpass both organic
and gustatory sensations, as an instrument of ex-
ternal perception.

Touch. — Under the generic sense of touch are
comprised a variety of classes of feeHngs widely
different from each other. Consequently, very early
in the history of Psychology, we meet wdth discus-
sions as to whether this term does not include several
specifically distinct senses. Aristotle^ called attention
both to the close relationship of taste with touch,
and to the divergent nature of sensations of tem-
perature, of softness and hardness, and of contact
proper. It would certainly seem that sensations
of temperature, differing so much in quality from
those of touch proper, awakened, moreover, by
distant objects, and seated either in different nerves
or different properties of nerve, from those of our
tactual feelings, have as strong claims to be con-
sidered the utterances of a separate sense as our

^ Aristotle, in the De Anima, II. 11. 22 — 24, holds a plurality of
senses to be contained under the generic faculty of touch. Else-
where, in the De Gen. Animalium, he seems to adopt the monistic
view. St. Thomas, however, prefers to look on these sensations
as merely differenv classes of feelings comprised under one tactua.
sense, the formal object of which has not received a definite namel
(Cf. Sum. i. q. 78. a. 3 ; also SchifTini, Disp. Mctaph. Vol. I. p. 322.)



THE SENSES. 69



gustatory states. Since, however, every proposed
subdivision of touch into separate senses appears
open to grave objections, and since the question is
really of no very great importance, the most con-
venient plan will be to distinguish and describe
separately the leading modes of sensibility included
under touch in its widest sense, without deciding
whether they should be assigned to different faculties.
These forms of consciousness are : (i) the organic
sensations, (2) the sensations of temperature, (3) touch
proper, and (4) the muscular sensations.

The Organic Sensations, Common Sensibility,
Ccenaesthesis, or the Vital Sense.— Under these
various designations are included the numerous modes
of sensuous consciousness attached to the organism as
a whole, or to particular portions of it. Their essential
function is to inform us, not of the properties of the
extra-organic world, but of the good or ill condition of
our own body. Prominent among them are the systemic
sensations, comprising those of the alimentary canal,
such as the feelings of hunger, of thirst, and repletion,
the sensations of respiration, of circulation, and such
other states as are normal to the system. In addition
to these, the chief remaining organic sensations are
those arising from disease, and from laceration or
fracture of any part of the organism. Estimated from
a cognitional point of view, the organic sensations are
of little importance. With the exception of particular
hurts, they are of an indefinite and obscure character.
They can be but very feebly reproduced in imagination.
Being in great part beyond the range of touch and
sight, they are vaguely and imperfectly localized, and
they give us practically no information regarding the
external world.* On the other hand, as sources of

^ Common sensibility has, however, great importance from an
intellectual standpoint in this respect, that it is the source of much
error. It may seriously distort men's judgments. Peace and war
have at times depended on the Prime Minister's digestion.



70



SENSUOUS LIFE.



pleasure and pain, they possess immense influence over
the tenour of our existence, and they are of the greatest
utihty as guardians of our physical health.

Sense of Temipersiture.— Physiological conditions.—



Online LibraryMichael MaherPsychology: empirical and rational → online text (page 7 of 63)