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attained by experience. Their opponents, however, would argue
that though illusory in the present case, the single apprehension is
due to native disposition and not merely to association.

^^ The reader interested in the question will find the empirical
doctrine supported by Carpenter, op. cit. §§ 168— 171, and Bern-


The importance of binocular vision in the perception of
soHdity and distance is very great. The muscular tension
involved in the convergence of the axes of the two eyes, and
the dissimilarity in the two retinal impressions, confer an
immense advantage on the double organ. Somewhat analo-
gously to the case of the two hands in the sense of touch,
and to the two ears in hearing, the twin members of the
visual faculty, by means of their different standpoints, are
enabled to bring forward valuable contributions of a new
character. Moreover, though double-contact aids us by two
distinct and separable experiences, while ordinarily in sight
but one sensation is consciously realized, yet the effect of the
second visual organ, whether due to experience or connate
aptitude, is such that we obtain an instantaneous perception
of the third dimension of space.

Erect Vision. — In addition to binocular vision, a second
"anomaly" of sight is found in the perception of objects as
erect while the image on the retina is inverted. Some writers
refuse to admit the existence of any special difficulty. We do
not, they point out, see the retinal image but the object, and
it is simply a law of our nature that an inverted image
awakens the perception of an erect object. Others accen-
tuate the fact that during the transmission of the retinal
impression to the brain in the form of a neural tremor, the
original spatial relations of the parts must be lost, and so
there is no reason why the resulting mental state should
redistribute them in their old position. The erection of the
object will then be due either to innate disposition or acquired
habit. Dr. Carpenter holds that " one of the most elementary
of our visual cognitions is the sense of direction, whereby we
recognize the relations of the points from which the rays
issue and thus see the objects erect, though their pictures on
the retina are inverted." ^^ By this "extradition," rays of
light falling from above or below will be referred back to their
source. He appeals to the operations for cataract as con-
firming his view. The question is, however, of no great
philosophical significance.

stein, The Five Senses, pp. 128, seq. On the other side, of. R. S.
Wyld, op. cit. pp. 221 — 227. P. Salis Sewis, Delia Conoscenza Sensi-
tiva, pp. 483 — 486, opposes the physiological explanation which
he traces back to Galen. La Psychologic Allemande Contemporaine,
pp. 118 — 145, by M. Ribot, gives an account of the dispute between
Nativists and Empiricists in Germany. However, this book, which
is written entirely from an empiricist standpoint, is very unreliable.
^^ Mental Physiology, § 165.


Auditory Perception. — The ear gives us origi-
nally no knowledge of the spatial relations of the
external world, nor even of the nature of the objec-
tive cause of the sensations of sound. Of the
acquired perceptions of this faculty the most re-
markable are the sense of the direction of a sounding
body, and the sense of its distance. Both are due to
association, and neither of them reach in man a
very high degree of perfection. If while our eyes
are closed a noise is produced near us by the con-
cussion of two objects, such as keys, we shall find
it almost impossible to localize the sound, especially
when the experiment is performed above our head
or near our feet. In mature life we estimate the
distance of a familiar sound by means of its in-
tensity. If it is of a rare character, such as that
of thunder or of the explosion of gunpowder, we
feel completely at a loss. The discrimination of
direction is dependent on the difference in the
effects produced in the two ears, and also on the
variation in the character or intensity of the sound
brought about by moving the head. An object on
the right side makes a stronger impression on the
right than on the left ear, and the sound is intensified
by bringing the head or body to that side, or by
setting the ear in a more direct line with the
sonorous object. Hares and other animals endowed
with large movable ears far surpass man in this
respect. Careful cultivation may extend consider-,
ably the power of distinguishing faint sounds, and,
we find certain uncivilized tribes, as well as some
species of the lower animals, in which this sense has '



been developed to a surprising degree as a means
of ascertaining the advent of their foes or their prey.
Its imperfection as an imformant regarding space
is partially redeemed by the fineness of its appre-
ciation of time lengths, and to this quality its value
not merely as the musical faculty, but as the instru-
ment of social communication is largely due.

Gustatory and Olfactory Perception. — Neither
the sense of taste nor that of smell afforded us origi-
nally an immediate perception of external reality.
If we make the experiment of tasting a liquid of
moderately sweet or sour flavour, which is at the
same temperature as the organ, we shall find that
even in mature life the resulting sensation is of a
vague ill-defined character, and contains little more
direct reference to the external world than a head-
ache, or a general feeling of depression. In
experience, however, special tastes have been found
to be invariably excited by objects possessing par-
ticular tactual and visual qualities, and therefore the
three classes of sensation come to be associated so
that either may recall the others. By cultivation
this faculty can be developed in a very surprising
degree, and the expert can detect variations in the
flavour of tea, wine, and other articles so faint as to
be utterly imperceptible to the ordinary mortal. The
first odours which assailed our nostrils probably
awoke us up to an indefinite pleasurable or painful
feeling, and to nothing more. But after a time
we grew to associate certain smells with particular
objects known by touch and sight, and as the
higher activities of the mind unfolded themselves


we began to apprehend the former as the cause of
the latter. To the circumstance that this sense is
stimulated by effluvia of distant bodies, much of its
superiority to taste, both in point of refinement and
of cognitional importance, is due. As revealing
future gustatory experiences, and giving timely
warning of poisonous or unwholesome food, olfac-
tory perception becomes an instrument of con-
siderable value. This faculty, like that of taste, is
susceptible of a high degree of cultivation, and in
the absence of some of the other senses it has
reached a remarkable degree of acuteness.

Objections solved.— The account we have just given of
the gradual growth of perception obviates various difficulties
urged against the doctrine of Natural Reahsm. Mr. Bain, for
instance, objects against Hamilton that the terms " external,"
"independent," and " reahty " " are not simple and ultimate
notions, but complex and derived," and consequently that
"it is inadmissible to regard any proposition involving them
as an ultimate fact of consciousness." ^^ Undoubtedly these
terms in ordinary language imply a variety of elements which
it would be absurd to assert are all given in the " primitive
unanalyzable dictum of consciousness." Accordingly, to main-
tain that the first sensation of pressure or sight revealed to
the infant a material world as external, independent, and real,
in the full significance of these words, would be as unjustifi-
able as to hold that the first glance at a triangle or circle
presents to us all its geometrical properties. Starting from
impressions of sight and touch which vaguely present to us
extended reality other than our perceiving mind, our present
well-defined knowledge of our own sentient organism, and of
objects external to it, became gradually elaborated. The
continuous existence of these realities when unperceived,
which especially establishes their independence of the Ego^
is guaranteed by memory, reflexion, and inference, and not
by direct intuition. Finally, through the same means we
learn to distinguish between the illusions of the imagination
and the genuine deliverances of the external senses, and so
come to comprehend the full meaning of reality.

^^ Mental Science, p. 120.


The objection that we cannot have an immediate know-
ledge of an " external reality," that " it is impossible to
understand how the mind can be cognizant of a thing
detached from itself," ^^ is equally futile. It is at least fully
as impossible to understand how the mind can be cognizant
of itself. How mind and body are united, Jiow either can act
upon the other, or indeed how any one thing can 7nove
another, are to our present faculties insoluble questions ; but
the fact that there is interaction cannot be denied any more
than the growth of plants or the existence of gravitation,
merely because we cannot imagine how such an event is
possible. If the living body is informed and animated
throughout its whole being by a spiritual soul, why should not
the sentient organism so constituted be capable of responding
to a material stimulus by an immediately percipient act ?
A priori dogmas as to what is or is not impossible are here
out of place, especially in the hands of empiricists. To
experience we must appeal, and this testifies that in sensa-
tions of pressure and sight we are immediately percipient of
something other than our own mental states, whilst observa-
tion of many of the lower animals proves that they can
accurately appreciate spatial relations from birth.

Co-operation of External Senses, Internal
Sense, and Intellect. — We have endeavoured, in
the present chapter, to trace the growth of each of
the external senses separately, and we have tried to
confine ourselves to the development of the sensuous
factor in apprehension. But in real life there is no
such isolation. The external senses are all con-
nected with the same brain, and they are all faculties
of the same mind. Their several activities are
accordingly unified in the same interior sensuous
consciousness. In human beings, as well as in the
lower animals, the operations of the senses are
synthesized by internal sentiency, and apart from
all higher rational activity, the sensations of the
different senses are obscurely felt as similar or

1'^ Mental Science, p. 209.


But in man, during mature life, even the
simplest acts of perception usually involve in-
tellectual activity, and it is virtually as impossible
to assign the exact date of the first awakening of
rational cognition as it is to point to the birth of
the primitive free volition. In both departments
lower grades of consciousness, sentiency and spon-
taneity, precede as necessary conditions the higher
forms of mental life ; and to the child during the
years of early infancy the existence of the external
world is given as an instinctive and indestructible
belief, and its reality is for him little more than that
of sensations and possibilities of sensations.

Dr. Porter very aptly remarks: "It is quite conceivable,
as has been already suggested, that before those percepts
(perceived things) and sensations (qualities apprehended by
sensations) are connected under the relation of substance
and attribute, they should be known as constant attendants,
co-existent or successive, and that, simply as conjoined, the
presence or the thought {i.e. sensuous image) of the one
should, under the laws of association, suggest the thought of
the other. It is under this relation that things and properties
are known to the animal. It is obvious that the animal
cannot and does not distinguish the relation of conjunction
from that ot causation. If he has experienced one sensation
or sense-percept in connection with another, the repetition of
the one brings up the image of the other, and the pain and
pleasure, the hope and fear, which are appropriate to it.
The dog connects with the whip in the hand of his master
the thought (image) of chastisement and pain ; with the sight
of his gun or his walking-stick, the excitement of a ramble or
of sport." i«

Intelligent Cognition not mere Instinctive Belief.—
It is through a confusion between the spontaneous faith
embodied in the primitive percipient act and the rational
conviction evoked in the developed consciousness by intel-
lectual perception, that Reid and others were misled into
describing our assurance of external reality as an instinctive

18 The Human Intellect, § 166.


&^//^/ irresistibly suggested by the sensation. Instinctive belief
stands opposed to intelligent cognition as being blind and
irrational. No grounds can be assigned for its existence,
and no cogent reason can be adduced for its validity. The
mere fact that a mental state of this character is inde-
structible does not alone afford it a sufficient philosophical
guarantee, while the appearance of idealist philosophers
would seem to imply that such a faith can at all events suffer
temporary eclipse. But our knowledge of material objects
is not of this kind. However blind and unintelligent may be
the trust of the infant or the brute in an external world,
developed cognition in man is essentially other than im-
pulsive faith ; and his certainty of a material universe, au
assurance in which rational intuition, abstraction, reflexion,
and inference are involved, and which is based on reasons
as solid as those we have already advanced, is most erron-
eously described as an instinctive belief.

Mental and Cerebral development. — Mental development is
marked by growth in power, enlargement in range and
variety, and increase in the complexity of our mental activi-
ties. Much industry has been recently devoted to the
systematic observation of the working of the faculties of the
mind from earliest childhood, and although the psychologist's
interpretations of the infant's mental states may remain of
doubtful value, careful study of facts must ultimately prove
fruitful in the interests of truth. Among the results, partly
physiological, partly psychological, claimed to be established
are the following.

The weight of the human brain at birth is about one-sixth
of that of the whole body. The brain more than doubles its
size during the first year, after which its increase is much less
rapid, and although it continues to grow very slowly to
middle life, it has nearly reached its full size by the end of
the seventh year, At maturity it averages between one-
fortieth and one-fiftieth of the weight of the body, reaching in
normal adult Europeans from about forty-six to fifty-two
ounces. Whilst during infancy it thus grows rapidly in bulk,
it also exhibits increasing distinctness and perfection in its
several parts, and its convolutions become deeper and more
marked. The sense-organs also, though very imperfect at
first, develop still more speedily, and within a few weeks, or
at most a few months, they attain maturity. Experiments go
to show that the newly-born child is deaf, probablj' owing to
the presence of a fluid in the internal cavit}- of the ear, which
is only gradually replaced by air. At first, sound produces
merely a vague shock, The muscular control over the eves


is imperfect, and according to some observers during the first
days of its life the infant merely distinguishes light from
darkness, whilst the capacity to discriminate colours remains
very feeble for some weeks. ^•* The child seems to be unable
to distinguish different distances, by means of sight. Although,
as we have already observed, this aptitude is enjoyed from
the beginning in a completely developed condition by some of
the lower animals. Sensations of contact are of a similarly
indefinite character. On the whole it is probable that the
consciousness of the infant during the first weeks of its life is
of a vague, indefinite, drowsy character, in which there is
little or no awareness of the various qualities of sensations
which will become so widely differentiated later on.^°

With varied and contrasted experiences, however, the
sensibility to different stimuli rapidly improves, and the
monotony of the earher somnolency is more and more broken
up. Each stimulation leaves a certain residual effect in the
faculty, and repetition of an impression, while strengthening
the power exercised, also tends to awaken a faint curiosity
and interest, and the infant begins to compare in a semi-
conscious way different experiences, and also to recognize
them on their recurrence. As definiteness of impressions is
increased memory improves, and conscious attention is called
more and more into play, and intellect proper begins to exert
itself. The primary tendency of all mental activity is objec-
tive — self-consciousness coming later. The course and the
range of development is determined in part by inherited
temperament, in part by surrounding circumstances, physical,
intellectual, and moral.

Periods. — The periods of development are variously divided
by different writers, but in general the following are recog-
nized as distinct epochs. Infancy, reaching to nearly the end

13 Cf. Preyer, The Mind of the Child, Part I. pp. 180— 1S3. Some
of his conclusions, however, seem very hazardous and scarcely
warranted by the evidence. Their uncertainty illustrates clearly
the grave difficulties inherent in the objective method as employed
in Comparative Psychology.

2" "The baby assailed by eyes, ears, nose, skin, and entrails at
once, feels it all as one great, blooming, buzzing confusion." (James,
Vol. I. p. 488.) J.Ward {"Psychology," Encyc. Brit. ,gih Edit.) similarly
insists that the primitive consciousness must be a sensory continuum,
a homogeneous mass, as it were of feeling in which the separate
elements have to be gradually discriminated and differentiated by
subsequent experiences. This is a striking reversal of the old
associationist " atomistic " view which conceived mental develop-
ment as mainly a process of fusion or "chemical combination" of
originally distinct impressions.


of the second year, during which the several faculties of
sense-perception reach maturity, the power of locomotion is
imperfectly acquired, and the first efforts at speech are made.
Childhood comes next, reaching to the seventh year. Memory
and imagination show considerable progress. Curiosity
frequently manifests itself, and the so-called "play-impulse"
or tendency to spontaneous, random movement is active.
A lull self-conscious knowledge of his own personality is
reached early in this period, although the general tendency of
the mind is objective ; and the power of voluntary self-control
and reflective obedience to rule is ordinarily sufficiently
developed before the eighth year to constitute the child
responsible for his acts where temptation does not exceed a
moderate degree of strength. For this reason moral theolo-
gians have fixed on the seventh year as the date about which
the " use of reason " is commonly reached.

The next seven years mark the period of boyhood, during
which the faculty of memory increases in strength and intel-
lectual abstraction comes more into play. Self-control too
grows in power, and individual peculiarities reveal them-
selves. This is especially the plastic period when the founda-
tions of those moral and intellectual habits are to be laid
which will in great part determine the quality of the boy's
future career. If habits in conflict with truthfulness, generosity,
obedience, or purity are in possession at the age of fifteen, it
is extremely difficult to dislodge them afterwards.

The period of youth, covering the next seven years, marks
the final "setting" of the character in various directions.
Whilst the memory and imagination continue active, the
intellectual faculty of abstract conception, judgment, and
reasoning rapidly expands, and the power of introspection
also increases. The emotions and passions come into pro-
minence. This is especially the season for building up ideals.
It is the age of enthusiasm, of poetry, and of fancy, but it is
also the epoch during which our most important intellectual
convictions and moral habits crystallize and determine for
good or ill the course of our whole future life.

Primary and Secondary Qualities of Matter. —

Oar knowledge of the smell, sound, taste, or tempera-
ture of objects differs widely in character from our cog-
nition of their extension, figure, or number. The latter
are called primary, the former secondary qualities of matter.
The significance of this difference has played a prominent
part in the history of the Philosophy of Perception in


modern times, especially in England, but the distinction
was clearly grasped in its most essential bearings by
Aristotle and St. Thomas. Aristotle distinguished
between ''common" and "proper sensibles," and
further between the latter in a state of formal actuality
or energy (eV ivcpyeia, in actu), and in a dormant or
potential condition-^ (eV Suva/^ct, in potentia). The " proper
sensibles " are the qualities in bodies which correspond
to the specific energies of the several senses — colour,
sound, odour, taste, temperature, and other special
tactual qualities. Under the " common sensibles " were
mcluded extension, figure, motion, rest, and number.
They are perceived through, but smiultaneously with,
the sensibilia propria, and by more senses than one.
Moreover, the sensihilia propria do not exist in a state of
actuality except when perceived, but only virtually as
dormant powers of matter. To this latter most profoundly
important distinction, erroneously imagined to be a
discovery of modern philosophy, we will return again.
Aristotle's doctrine on both points was adopted by
St. Thomas,' - who reduced the various forms of
common sensibles to that of quantity. This was con-
ceived to be the most fundamental attribute of matter,
and the various qualities which give rise to the special
sensations were looked upon as properties inhering

21 There was also another distinction recognized by the
Peripatetic school, that of sensibile per se and sensibile per accidens.
That is sensibile per accidens which is apprehended indirectly
through being accidentally conjoined with something which is
sensibile per se ; and in this signification individual corporeal sub-
stances were said to be sensibile per accidens, " ut si dicimus quod
Diarus vel Socrates est sensibile per accidens, quia accidit ei esse
album." (St. Thomas, De Anima, Lib. II. 1. 13.) Both sensibilia propria
and sensibilia communia were held to be sensibilia per se ; the former,
however, being classed as per se primo vel proprie, the latter as per se
secundo. The several "proper sensibles " (per se primo) were defined
to be the formal object, or appropriate stimulus of the different
special senses. The " common sensibles " (sensibilia per se sed non
proprie), extension, figure, &c., manifest themselves through, but
simultaneously with, the sensibilia propria. They are thus not
mediate acquisitions derived from the former, but forms of reality
directly revealed through them.

- Cf. Sum. i. q. 78. a. 3. ad 2. and iii. q. 77. a. 2.


in it. From this to the modern division into primary
and secondary quaHties the transition is obvious.

Descartes, between whom and Locke the credit
of the discovery of the ancient distinction has been
supposed to lie, taught that the attributes, Magnitude,
Figure, Motion, Situation, Duration, and the Hke, are
clearly perceived. We have an idea of them as they
may be in the object. On the other hand, Colour, Pain,
Odour, Taste, et cetera, are not thus apprehended. We
have only a confused and obscure knowledge of some-
thing or other in the external body which causes these
sensations in us.

Locke, who borrowed from Galileo the terms
Primary or Real and Secondary Qualities to mark the old
distinction between the common and proper sensibles, gives
solidity, extension or bulk, figure, motion or rest, and
number, as included in the first class. These attributes

Online LibraryMichael MaherPsychology: empirical and rational → online text (page 15 of 63)