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sensations and representations ; between the new elements im-
mediately given and the residues or after-effects of these elements,
which rc-emcrge. So soon as elements acquired at an earlier stage
are concerned in the apprehension of new elements, there is no
longer pure sensation ; a certain amount of thought is then com-


bined with the sensuous perception. And further, if we disregard
this, and endeavour to conceive a consciousness which shall consist
of nothing but sensations, there still remains the question whether
even these are perfectly simple and independent of one another,
or whether there is not constant combination and interaction
between th6m.

It is evident that the provisional account of consciousness given
in an earlier chapter (II. 5) cannot be correct, if sensations are
perfectly simple and independent. In that account we found the
characteristic feature of consciousness to be the fact that it makes
its appearance in a scries of elements not mutually independent,
but on the contrary essentially conditioning one another, a close
interaction which had its most typical expression in memory. The
correctness of this account must now be to some extent tested.

2. By purely psychological observation the simplicity of our
sensations can be ascertained only to a certain degree. We can
never be quite certain that we have before us something unanalys-
able. At the point where introspective psychology breaks off, the
experimental physiology of the senses takes up the thread, and has
in some instances established that the apparently simple psycho-
logical phenomenon involves an intricate and complex physiological
process. The possibility cannot therefore be excluded, that the
psychological simplicity may be merely the result of previous
combination below or at the threshold of consciousness.

Organic or general sensations are, as a rule, of a manifold,
chaotic character, a fact connected with their obscure and only
slightly articulate nature. Stimuli from the organs of respira-
tion, circulation, and digestion operate in conjunction without
separately attaining to consciousness. Such a sensation as, e.g.,
nausea, has something complex about it even to immediate percep-
tion, as may be seen from the fact that some have proposed to class
it among sensations of taste, some among muscular sensations,
while others have wished to distinguish it from either class. Many
of the sensations of taste and smell are so mixed up with sensations
of touch that they cannot be called anything pure and simple.
Salt, sour and astringent tastes, pungent and sharp smells, are
really combinations of sensations of taste and smell with sensations
of touch. The pleasantness of many sorts of food {e.g. jelly) is
ceri.ainly derived chiefly from their effect upon the delicate skin of
the palate, and is therefore much more a question of touch than
of taste. In the wider sense in which it is customary to speak of


taste, the Shah of Persia was right when he reproached Europeans
(who used knives and forks) for not knowing that the sense of taste
begins in the finger tips. Again, not only smell, but also sight,
plays a part in the enjoyment of food, for we cannot tell the taste
of a thing so well in the dark as when we can call sight to our aid.
An isolation is here possible only by artificial means, and will
often result in showing that the sense of taste proper has nothing
at all to do with the apparent sensations of taste.

The sensation we have when we lift a weight from the ground
is very complex. Contact, pressure, and muscular effort mingle in
an indefinite whole, which becomes the more complicated from the
fact that several different muscles, and in different degrees, are
called into play. And yet it may seem to us as though we had a
simple sensation.

In respect of sensations belonging to one definite sense, it might
be expected that the matter would be simpler and plainer. But
even in this case it may be disputed whether a sensation is given
in immediate apprehension as simple or as complex.

Goethe held, c.i^., that only the sensations of yellow, blue, and
red are simple. These he called primary colours, and the other
colours he regarded as composed of these, since, as he thought, in
violet he could trace red and blue ; in green, yellow and blue ; and
in orange, yellow and red.^ At the present day, on the contrary,
E. Hering maintains that green is a perfectly simple sensation, and
that yellow and blue can never be experienced together as elements
of a compound colour. He draws up accordingly a scale of four
primary colours— red, green, yellow, and blue." That such skilled
observers should come to such decidedly different results is a proof
of the untrustworthiness of direct psychological apprehension in
these doubtful points. The matter itself admits evidently of
another possibility, namely, that a// sensations of colour may be
simple. Any one who accustoms himself to abstract from recollec-
tions and preconceived ideas, and to concentrate his attention on
a narrow zone of the scale of colours, will certainly be able to
obtain a perfectly simple sensation of every single colour, and if
language had words enough, would feel the need of expressing
each of these shades of colour by a separate word. It must be
added that the dispute would begin all over again, if we had to
specify which precise shade of red, green, etc., was the primary

1 Farbenlchre, vol. i., § 60. [Eng. tr. by Eastl.ike.]

2 Zur Lehrevom Lkhtsinne, ind ed., § 38. These four already been given by
Leonardo d.i Vinci.


colour. Each several observer would name his shade, and would
maintain that all other shades resulted from admixture of other
colours. When expressions of language contain a reference to
certain primary colours, this is probably to be explained either by
the fact that the colours of certain striking natural objects (green
plants, red blood, etc.) were early imprinted upon and controlled
the mind, or by the fact that the retina is more susceptible to some
colours (especially yellow) than to others.^

But while a distinction may not be drawn between primary and
composite colours, there is on the other hand reason to believe
that every colour-stimulus is accompanied by a colourless light-
stimulus, which passes, when the strength of the stimulus is
greatly decreased or increased, into distinctly colourless sensation
(of white, grey, or black). It is only with a stimulus of medium
strength, that the colour-stimulus (the chromatic irritation) pre-
ponderates over the colourless stimulus (the achromatic irritation).
This admixture of a chromatic and an achromatic process in the
visual organ is inferred partly from the fact that those parts of the
retina situated farthest from the point of clearest vision (the yellow
spot, fovea centralis) are under ordinary circumstances colour-
blind, partly from the fact that every sensation of colour passes
into a colourless sensation if the strength of the stimulus is
sufficiently decreased or increased. -

In the province of hearing sensations seem to be compound also.
Every tone has its timbre, that is to say consists of a combination,
different according to the source of production, of a fundamental
tone with weaker " higher tones " or harmonics. The same tone
therefore sounds different, if produced on different instruments. But
just as the practised ear in a concert may distinguish the share of
each instrument in the effect produced, so may specially endowed or
well-practised organs of hearing pick out the partial tones in a
sound, even though to immediate sensation it seems quite simple.
A simple tone is thus properly an abstraction, since we certainly
never hear tones or sounds quite without timbre. There is only a
difference of degree between a tone {KUmg) and a chord {Zusavi-
tnenklang), a difference conditioned by the weakness or strength of
the harmonics relatively to the fundamental tone.'

1 C/. V.-Krenchel, Out Gritnif/arTer ('' On the Primary Colours"), Copenhagen, 1880,
p. II, seq.; (also in (irafe's Archiv. fur Ophthalmologie, 1880); Wundt, Physiol.
Psychologic, i., p. 415 (3rd ed. i., p. 451); Fick, Die Lehre von der Lichtempfindung
(" The 'I'heory of the Sensation of Light "). (Hermann, iii., i), p. 192, sc].

' Wundt, Physiol. Psychologic, 1, p. 453 (3rd ed. i, p. 491)

3 \Cf. Bernstein, live Senses 0/ Man, p. 245, seq. (Tr.)]


This theory, propounded Ijn- Uchnholtz and generally accepted,
shows how the compound nature of subjective sensations may be
established by way of physical and physiological experiment. The
sensation of tone {K'lang) is resolved into elements, the relations
among which dctcrniine the character of the sensation. But if this is
so with one set of sensations, will it not be the same with our other
sensations ? If we do not with these possess the power of tracing the
elementary sensations, out of which the sensation as presented to
consciousness is compounded, this may have to do with the fact
that the sense of hearing so far surpasses the other senses in the
delicacy with which it can discriminate differences and gradations.
The study of the sensation of hearing has at any rate shaken the
principle of the simplicity of sensations, and has opened a fresh
horizon at a point where the accessible psychological world seemed
to end.

There are, besides, certain phenomena whicli point to mental
elements simpler than those distinctly received through the senses.
The sensations experienced, when the attention is engaged in
another direction, or even when we arc suddenly surprised, have
no detinite cpialitative character. We start, note that something
has happened in or to us, but what this is, whether a light-stimulus,
a push, or an electric-shock, we do not know, — at any rate not at
the first moment. Thus the more sudden the sensation, and the
shorter its duration, the smaller the possibility of classifying it
under any one definite sense-quality. This applies also to cases
where the excitations are very weak and of very limited range ;
unless the excitation take effect actually on the palm of the hand or
on the face, it is not possible to determine in the case of a weak and
limited affection, whether it proceeds from contact or from heat. It
seems, then, that in the distinct sensations of temperature and touch,
we must recognise results of a combination, by which various ele-
mentary sensations are united into groups, which then appear to
consciousness as indissoluble unities. — A light-stimulus, if its effect
is confined to a very small portion of the retina, calls up only an
;dmost colourless sensation of white, even when the same stimulus
applied to a larger portion of the retina, produces the sensation of
a very intense colour. So that here again a very limited excitation
occasions no qualitative sensation.'

It accords with this, that the nerve-process, whatever its nature
may be, is carried on in pulsating beats or oscillations. It is the

1 Hermann's //rtwrf/i/a//, iii, i, p. 164, 169; iti., 2, p. 322.


highest law of the general physiology of the nerves, that a nerve-
process can never be set up by a state of equilibrium, but only by
sudden changes, effected with a certain rapidity, in the condition
of the nerve. A seemingly continuous nerve-process (a tetanus) is
really only brought about by a series of quickly succeeding changes
of equilibrium. The relations in the individual sense-organs, so
fiir as known, seem to accord with this law.^ The sensation, as we
know it, must correspond to several such beats or different
momenta of the oscillations ; in one single conscious instant, in one
momentary sensation, there is thus brought together what physio-
logically occupies several moments of time. And since the
structure and mode of action of the nervous system seems to be
throughout homogeneous, only one way is open to explain the
qualitative differences of sensations, to derive them, namely, from
the different ways in which the elementary sensations, which cor-
respond to the single nerve-pulsations or liberations of force, are
combined. Just as the different kinds of colour may find their
physiological counterpart in the different directions taken by the
same brain-molecule,"'^ so a further step may be taken and the
differences in the modalities of sensalion^he. conceived as having
their counterpart in yet deeper differences of form and direction
among the processes in the central and end organs. This is
the only way in which it is possible to understand how the
different senses can have arisen in the course of the evolution
of organic beings. The farther the descent from the higher
to the lower animals, the fewer the modalities found. That
which remains as starting-point in the development of sensory
activity, is the sense of touch. Out of this the special senses or
modalities must have arisen by differentiation. It accords with
this, that the special organs in all sensitive organisms are
modifications of the external integument.

This hypothesis (first proposed by Spencer) of the origin of our
specific sensations through combination of simpler elementary
sensations, opens up a wide horizon. But our chief interest
here lies in the fact that, in taking up with this hypothesis,

1 Funke in Hermann's Handltnch, iii,, 2, p. 328, scq. The above quoted principal law
of the physiology of the nerves was established by du Bois-Reymond in connection with
electrical stimuli, 1S45. L. Hermann, Atl^. Nervenphysiologit ("General Phys. of the
^i:Tvc^,")(Hand/>iic/!, ii., i), p. 50.

- V. Krenchel, 0»t Criiniifa?yier {\n German under the title "Uber die Hypothese
von Grundfarben," Gr.iic!, Arc/tiv fiir Ophthalmo/offie, 1880), p. 20, iiv/.

■' Modality is a term suggested by Helmholtz for what Fichte calls quality-circle
(Qualitcitski-cis) : the collective name for all sensations belonging to one class (sight,
sound, taste, &c.).


we tind at the confines of distinct consciousness, traces of a
work which, wliiie undoubtedly carried on below the threshold
of consciousness, conforms to the laws that govern conscious-
ness {cf. III). The general description of consciousness as
synthetic and connective, proves to be applicable also to the
ultimate elements to which we are led by analysis of compound
states of consciousness. If, then, consciousness is asserted to
be only a sum of sensations, the comment must at any rate be
made, that the units of this sum are not absolutely simple, but
have apparently arisen by synthesis of still simpler elements.
A sensation is only a relative conception, as is an atom in the
province of material nature.'

3. Closely connected with the question of the simplicity of
sensations is the question of their relative independence. Here
again the physiology of the senses yields interesting results.

A certain opposition has to be overcome in the end-organs of
the sensory nerves as well as in the nerve centres, before the
stimulus can produce its full effect ; but when once this opposition
is overcome, the effect will continue for some time after the ces-
sation of the stimulus. This is the general physical law of inertia,
as it comes into operation in the physiology of the nerves. The
several senses are not, however, all alike in this respect. The
greatest elasticity belongs to the sense of touch. By bringing the
linger in contact with a cog-wheel, which revolves at a certain rate,
we may have as many as 1000 distinct sensations per second. But
if the rate is increased still further, there results only one continuous
sensation. The sense of hearing comes closest to the sense of
touch. But that the latter has the advantage is apparent from the
fact that, if the hand is placed on a musical instrument, the
vibrations of even fairly high tones are felt as a whirring. In
experiments with one car, the crack of two electric sparks is heard
as distinct when the one sounds o'oo2 of a second before the other.
In experiments with Ijoth ears, the limit is higher (o"o64 of a
second). Electric shocks can still be distinguished when they
arrive at the rate of thirty-five in the second : if the rate is greater,
only one single sensation is experienced. On the forehead so
many as sixty shocks in the second can be distinguished. The
sense of sight stands lowest in respect of elasticity, a fact which is

1 With regard lo sensations of taste and smell, there are no trustworthy observations.
It cannot he clearly proved that these sensations can he recalled, since it is impossible to
he absolutely certain that remains of the matter tasted and smelt are not left in the
organs. Vintschgau in Hermann's Ilandbiich, iii., 2, pp. 221, 2S4.


accounted for by the nature of the end-organs. After observation
of a brightly iHuminated object, there remains an after-image when
the eves arc closed. The new impression consequently does not
find the place empty, but is combined with the after-effect of the
previous impression. If a disk, divided into equal alternate sectors
of white and black, is set to revolve quickly, the impressions are
fused, and there results a continuous sensation of grey, if about
twenty-four impressions come per second and if the light
equals ordinary daylight. A burning match, if swung round
quickly in the dark, presents the appearance of an illuminated
circle. When the revolutions are slow, the separate sensations are
clearly noted ; when the speed is increased, there is a scintillation,
and when increased still further, the impressions are all fused in
o7te sensation.'

The blind patient operated on by Franz, found it disagreeable,
even several months after the operation, to walk along much
frequented streets. The many different objects and the quick
movements of men, carriages, etc., so confused his sight that at
last he could see nothing ; the impression produced by the object
last seen not having disappeared before the succeeding object
called forth a fresh impression. In this case the separate im-
pressions were not completely fused, but produced a chaos
which made distinct apprehension impossible. And at every
stage of consciousness a certain rate of succession must be ob-
served if the sensations are to be distinct.

For a sensation to arise there must be not only a certain intet-^'al
of time, but also a certain contrast, between the impression it
accompanies and the preceding impression. There must be a
background, from which the new sensation may stand out.
If gently and gradually increased, a stimulus may remain un-
obser\ ed, even after it has reached a degree of strength which,
under other conditions, would call out sensation. The quite
gradual increase in strength of an electric current will at length
destroy a nerve subjected to its influence, without any sign of
sensation. By very gradual increase or decrease of tempera-
ture, a frog may be boiled or frozen to death without making
the smallest movement. Sensations of warmth or cold arise

1 Kick. Hermann's I/aiidlnic/t, iii., i,p. 211, seq. ; Exner, ibni., ii., 2, pp. 256-260. The
strong and persistent after-eiTects in the eye are an important argument for the photo-
chemical theory, according to which the setting free of the so-called visual purple m the
retina, effected hy rays of light, is the real stimulation of the visual nerve. Kiihne,
Chevtische Vorgiinge in der Netzhnut (" Chemical Processes in the Retina "), (Hermann,
iii., i), pp. 2-8, 261.


only when a change in the temperature of the skin is effected
with a certain rapidity. A sensation of temperature arises when
the sicin (or more precisely the thermic apparatus) acquires a
temperature which is sufficiently above or below its "zero-tempera-
ture" {i.e. the temperature which, at the points of the skin con-
cerned, is felt neither as warm nor as cold).^

Very weak stimuli are absorbed by previous or simultaneous
stimuli, without producing any special sensation. If a person has
been electrified for some instants by a strong current, he does not
notice a weaker one. If a strong current is received through one
hand and a weaker one through the other, the latter is not noticed.
If one point of a compass is placed on a painful wound and the
other on the skin surrounding it, and an equal pressure applied,
only one sensation will be felt, even though the distance between
the points be twice that at which two sensations would be produced
if both points were on the surface of the wound.^ Even Hippo-
crates taught that of two pains, occurring at the same time but not
on the same spot, the smaller would be suppressed by the greater.
Shakspeare makes King Lear express the same thought ; for grief
and rage he heeds neither rain nor storm, for " where the greater
malady is fixed, the lesser is scarce felt," as contrariwise, " When
the mind's free, the body's delicate." In a highly excited state
of consciousness, even strong impressions can obtain no great
hold. The ecstatic enthusiasm of martyrs must weaken their
sense of suffering. Similarly hypochondria and mental distraction
may prevent painful sensations ; the fixed idea which arrests con-
sciousness may be so strong, that no otlier impression is able to
attract the attention.

The tlwi'shold of consciousness, then, is not always at the same
level, but is raised when there is not a great enough contrast to
preceding or simultaneous impressions. On the other hand, it is
lowered under certain conditions, as a result of custom or ac-
commodation. If a sound is listened to as it dies away, it can be
followed down to a minimum strength, inaudible to any one who
has not heard it at the beginning. The eye can follow the
flight of a bird to a distance at which the bird could not be
discovered by any one freshly looking for it. It is easier for
consciousness to retain a given weak impression than to take in a

1 Cf. Kick, Anatomie itmi Physiologic der Sinnesorgane, p. 54; Heiiiig, De>
Teinf>e>\itursinn^ (Hermann, iii., •-•), p. 415, seq. ; Kichet, Rtcherclus iur la HensibiliU,

- Kicliet, Retherches. p. 168, 2J2.


fresh impression which in itself is stronger.' An example of the
lowering of the threshold of consciousness is given in the capacity
which prisoners, after long confinement in dark places, acquire for
observing the smallest objects and the faintest differences in the
light. In order to practise his eye in discriminating very small
differences of light, Lavoisier confined himself for six: weeks to a
room draped in black. — The lowering of the threshold of conscious-
ness is thus conditioned in a manner analogous to its raising ; the
gradual decrease of impressions does not destroy a sensation, any
more than their gradual increase produces one.

Perfectly constant and uniform impressions and states do not
come into consciousness, are not accompanied by sensations. The
pressure of the air is noticed only when it varies. The very rapid
movement of the earth carries us round without our knowing it,
because it is constant. We do not notice that the blood-vessels of
the retina cast shadows on the retina itself, because we have always
been accustomed to them ; these shadows do, on the contrary,
attract notice, when they are artificially cast on to parts of the
retina accustomed to stronger impressions of light. A substance
affords sensations of taste only if its taste is different from that of
the saliva. For the tongue is accustomed to the saliva, and
therefore deadened to its slightly salt taste.-

Fechner has tried to find a mathematical formula to express the
ratio in which the effect produced by each stimulus is determined
by the preceding stimulus. From experiments made by himself
and others, he thinks the rule may be deduced that the increase in
sensation, resulting from an iticrease in the strength of the stiimtlus,
depends, not on the absolute increase, but on the relation of the
increase to the precediitg stimulus. If the sensation is to increase
to a certain degree, the stimulus must increase the more, the
stronger it is to begin with. P'echner expresses this by saying
that the strength of the stimulus must increase in geometrical
progression, in order that the sensation may increase in arith-
metical progression. If the sensation is to rise from i to 2,
the stimulus must rise from 10 to 100 ; and that the one may

Online LibraryHarald HøffdingOutlines of psychology → online text (page 12 of 41)