DISCRIMINATION.
=Discrimination versus Association.=--On p. 15 I spoke of the baby's first
object being the germ out of which his whole later universe develops by
the addition of new parts from without and the discrimination of others
within. Experience, in other words, is trained _both_ by association and
dissociation, and psychology must be writ _both_ in synthetic and in
analytic terms. Our original sensible totals are, on the one hand,
subdivided by discriminative attention, and, on the other, united with
other totals,--either through the agency of our own movements, carrying
our senses from one part of space to another, or because new objects
come successively and replace those by which we were at first impressed.
The 'simple impression' of Hume, the 'simple idea' of Locke are
abstractions, never realized in experience. Life, from the very first,
presents us with concreted objects, vaguely continuous with the rest of
the world which envelops them in space and time, and potentially
divisible into inward elements and parts. These objects we break asunder
and reunite. We must do both for our knowledge of them to grow; and it
is hard to say, on the whole, which we do most. But since the
elements with which the traditional associationism performs its
constructions--'simple sensations,' namely--are all products of
discrimination carried to a high pitch, it seems as if we ought to
discuss the subject of analytic attention and discrimination first.
=Discrimination defined.=--The noticing of any _part_ whatever of our
object is an act of discrimination. Already on p. 218 I have described
the manner in which we often spontaneously lapse into the
undiscriminating state, even with regard to objects which we have
already learned to distinguish. Such anæsthetics as chloroform, nitrous
oxide, etc., sometimes bring about transient lapses even more total, in
which numerical discrimination especially seems gone; for one sees light
and hears sound, but whether one or many lights and sounds is quite
impossible to tell. Where the parts of an object have already been
discerned, and each made the object of a special discriminative act, we
can with difficulty feel the object again in its pristine unity; and so
prominent may our consciousness of its composition be, that we may
hardly believe that it ever could have appeared undivided. But this is
an erroneous view, the undeniable fact being that _any number of
impressions, from any number of sensory sources, falling simultaneously
on a mind_ WHICH HAS NOT YET EXPERIENCED THEM SEPARATELY, _will yield a
single undivided object to that mind_. The law is that all things fuse
that _can_ fuse, and that nothing separates except what must. What makes
impressions separate is what we have to study in this chapter.
=Conditions which favor Discrimination.=--I will treat successively of
differences:
(1) So far as they are directly _felt_;
(2) So far as they are _inferred_;
(3) So far as they are _singled out in compounds_.
=Differences directly felt.=--The first condition is that _the things to
be discriminated must_ BE _different_, either in time, place, or
quality. In other words, and physiologically speaking, they must awaken
neural processes which are _distinct_. But this, as we have just seen,
though an indispensable condition, is not a sufficient condition. To
begin with, the several neural processes must be distinct _enough_. No
one can help singling out a black stripe on a white ground, or feeling
the contrast between a bass note and a high one sounded immediately
after it. Discrimination is here _involuntary_. But where the objective
difference is less, discrimination may require considerable effort of
attention to be performed at all.
Secondly, _the sensations excited by the differing objects must not fall
simultaneously, but must fall in immediate_ SUCCESSION upon the same
organ. It is easier to compare successive than simultaneous sounds,
easier to compare two weights or two temperatures by testing one after
the other with the same hand, than by using both hands and comparing
both at once. Similarly it is easier to discriminate shades of light or
color by moving the eye from one to the other, so that they successively
stimulate the same retinal tract. In testing the local discrimination of
the skin, by applying compass-points, it is found that they are felt to
touch different spots much more readily when set down one after the
other than when both are applied at once. In the latter case they may be
two or three inches apart on the back, thighs, etc., and still feel as
if they were set down in one spot. Finally, in the case of smell and
taste it is well-nigh impossible to compare simultaneous impressions at
all. The reason why successive impression so much favors the result
seems to be that there is a real _sensation of difference_, aroused by
the shock of transition from one perception to another which is unlike
the first. This sensation of difference has its own peculiar quality, no
matter what the terms may be, between which it obtains. It is, in short,
one of those transitive feelings, or feelings of relation, of which I
treated in a former place (p. 161); and, when once aroused, its object
lingers in the memory along with the substantive terms which precede and
follow, and enables our _judgments of comparison_ to be made.
Where the difference between the successive sensations is but slight,
the transition between them must be made as immediate as possible, and
both must be compared _in memory_, in order to get the best results. One
cannot judge accurately of the difference between two similar wines
whilst the second is still in one's mouth. So of sounds, warmths,
etc.--we must get the dying phases of both sensations of the pair we
are comparing. Where, however, the difference is strong, this condition
is immaterial, and we can then compare a sensation actually felt with
another carried in memory only. The longer the interval of time between
the sensations, the more uncertain is their discrimination.
The difference, thus immediately felt between two terms, is independent
of our ability to say anything _about_ either of the terms by itself. I
can feel two distinct spots to be touched on my skin, yet not know which
is above and which below. I can observe two neighboring musical tones to
differ, and still not know which of the two is the higher in pitch.
Similarly I may discriminate two neighboring tints, whilst remaining
uncertain which is the bluer or the yellower, or _how_ either differs
from its mate.
I said that in the immediate succession of _m_ upon _n_ the shock of
their difference is _felt_. It is felt _repeatedly_ when we go back and
forth from _m_ to _n_; and we make a point of getting it thus repeatedly
(by alternating our attention at least) whenever the shock is so slight
as to be with difficulty perceived. But in addition to being felt at the
brief instant of transition, the difference also feels as if
incorporated and taken up into the second term, which feels
'different-from-the-first' even while it lasts. It is obvious that the
'second term' of the mind in this case is not bald _n_, but a very
complex object; and that the sequence is not simply first '_m_,' then
'_difference_,' then '_n_'; but first '_m_,' then '_difference_,' then
'_n-different-from-m_.' The first and third states of mind are
substantive, the second transitive. As our brains and minds are actually
made, it is impossible to get certain _m_'s and _n_'s in immediate
sequence and to keep them _pure_. If kept pure, it would mean that they
remained uncompared. With us, inevitably, by a mechanism which we as yet
fail to understand, the shock of difference is felt between them, and
the second object is not _n_ pure, but _n-as-different-from-m_. The pure
idea of _n_ is _never in the mind at all_ when _m_ has gone before.
=Differences inferred.=--With such direct perceptions of difference as
this, we must not confound those entirely unlike cases in which we
_infer_ that two things must differ because we know enough _about_ each
of them taken by itself to warrant our classing them under distinct
heads. It often happens, when the interval is long between two
experiences, that our judgments are guided, not so much by a positive
image or copy of the earlier one, as by our recollection of certain
facts about it. Thus I know that the sunshine to-day is less bright than
on a certain day last week, because I then said it was quite dazzling, a
remark I should not now care to make. Or I know myself to feel livelier
now than I did last summer, because I can now psychologize, and then I
could not. We are constantly comparing feelings with whose quality our
imagination has no sort of _acquaintance_ at the time--pleasures, or
pains, for example. It is notoriously hard to conjure up in imagination
a lively image of either of these classes of feeling. The
associationists may prate of an idea of pleasure being a pleasant idea,
of an idea of pain being a painful one, but the unsophisticated sense of
mankind is against them, agreeing with Homer that the memory of griefs
when past may be a joy, and with Dante that there is no greater sorrow
than, in misery, to recollect one's happier time.
=The 'Singling out' of Elements in a Compound.=--It is safe to lay it down
as a fundamental principle that _any total impression made on the mind
must be unanalyzable so long as its elements have never been experienced
apart or in other combinations elsewhere_. The components of an
absolutely changeless group of not-elsewhere-occurring attributes could
never be discriminated. If all cold things were wet, and all wet things
cold; if all hard things pricked our skin, and no other things did so:
is it likely that we should discriminate between coldness and wetness,
and hardness and pungency, respectively? If all liquids were transparent
and no non-liquid were transparent, it would be long before we had
separate names for liquidity and transparency. If heat were a function
of position above the earth's surface, so that the higher a thing was
the hotter it became, one word would serve for hot and high. We have, in
fact, a number of sensations whose concomitants are invariably the same,
and we find it, accordingly, impossible to analyze them out from the
totals in which they are found. The contraction of the diaphragm and the
expansion of the lungs, the shortening of certain muscles and the
rotation of certain joints, are examples. We learn that the _causes_ of
such groups of feelings are multiple, and therefore we frame theories
about the composition of the feelings themselves, by 'fusion,'
'integration,' 'synthesis,' or what not. But by direct introspection no
analysis of the feelings is ever made. A conspicuous case will come to
view when we treat of the emotions. Every emotion has its 'expression,'
of quick breathing, palpitating heart, flushed face, or the like. The
expression gives rise to bodily feelings; and the emotion is thus
necessarily and invariably accompanied by these bodily feelings. The
consequence is that it is impossible to apprehend it as a spiritual
state by itself, or to analyze it away from the lower feelings in
question. It is in fact impossible to prove that it exists as a distinct
psychic fact. The present writer strongly doubts that it does so exist.
In general, then, if an object affects us simultaneously in a number of
ways, _abcd_, we get a peculiar integral impression, which thereafter
characterizes to our mind the individuality of that object, and becomes
the sign of its presence; and which is only resolved into _a_, _b_, _c_,
and _d_, respectively, by the aid of farther experiences. These we now
may turn to consider.
_If any single quality or constituent, a, of such an object have
previously been known by us isolatedly_, or have in any other manner
already become an object of separate acquaintance on our part, so that
we have an image of it, distinct or vague, in our mind, disconnected
with _bcd, then that constituent a may be analyzed out from the total
impression_. Analysis of a thing means separate attention to each of its
parts. In Chapter XIII we saw that one condition of attending to a thing
was the formation from within of a separate image of that thing, which
should, as it were, go out to meet the impression received. Attention
being the condition of analysis, and separate imagination being the
condition of attention, it follows also that separate imagination is the
condition of analysis. _Only such elements as we are acquainted with,
and can imagine separately, can be discriminated within a total
sense-impression._ The image seems to welcome its own mate from out of
the compound, and to separate it from the other constituents; and thus
the compound becomes broken for our consciousness into parts.
All the facts cited in Chapter XIII to prove that attention involves
inward reproduction prove that discrimination involves it as well. In
looking for any object in a room, for a book in a library, for example,
we detect it the more readily if, in addition to merely knowing its
name, etc., we carry in our mind a distinct image of its appearance. The
assafœdita in 'Worcestershire sauce' is not obvious to anyone who has
not tasted assafœtida _per se_. In a 'cold' color an artist would
never be able to analyze out the pervasive presence of _blue_, unless he
had previously made acquaintance with the color blue by itself. All the
colors we actually experience are mixtures. Even the purest primaries
always come to us with some white. Absolutely pure red or green or
violet is never experienced, and so can never be discerned in the
so-called primaries with which we have to deal: the latter consequently
pass for pure.--The reader will remember how an overtone can only be
attended to in the midst of its consorts in the voice of a musical
instrument, by sounding it previously alone. The imagination, being then
full of it, hears the like of it in the compound tone.
=Non-isolable elements may be discriminated, provided= =their concomitants
change.= Very few elements of reality are experienced by us in absolute
isolation. The most that usually happens to a constituent _a_ of a
compound phenomenon _abcd_ is that its _strength_ relatively to _bcd_
varies from a maximum to a minimum; or that it appears linked with
_other_ qualities, in other compounds, as _aefg_ or _ahik_. Either of
these vicissitudes in the mode of our experiencing _a_ may, under
favorable circumstances, lead us to feel the difference between it and
its concomitants, and to single it out--not absolutely, it is true, but
approximately--and so to analyze the compound of which it is a part. The
act of singling out is then called _abstraction_, and the element
disengaged is an _abstract_.
Fluctuation in a quality's intensity is a less efficient aid to our
abstracting of it than variety in the combinations in which it appears.
_What is associated now with one thing and now with another tends to
become dissociated from either, and to grow into an object of abstract
contemplation by the mind._ One might call this the _law of dissociation
by varying concomitants_. The practical result of this law is that a
mind which has once dissociated and abstracted a character by its means
can analyze it out of a total whenever it meets with it again.
Dr. Martineau gives a good example of the law: "When a red ivory ball,
seen for the first time, has been withdrawn, it will leave a mental
representation of itself, in which all that it simultaneously gave us
will indistinguishably coexist. Let a white ball succeed to it; now, and
not before, will an attribute detach itself, and the _color_, by force
of contrast, be shaken out into the foreground. Let the white ball be
replaced by an egg, and this new difference will bring the _form_ into
notice from its previous slumber, and thus that which began by being
simply an object cut out from the surrounding scene becomes for us first
a _red_ object, then a _red round_ object, and so on."
_Why_ the repetition of the character in combination with different
wholes will cause it thus to break up its adhesion with any one of them,
and roll out, as it were, alone upon the table of consciousness, is a
little of a mystery, but one which need not be considered here.
=Practice improves Discrimination.=--Any personal or practical interest in
the results to be obtained by distinguishing, makes one's wits amazingly
sharp to detect differences. And long training and practice in
distinguishing has the same effect as personal interest. Both of these
agencies give to small amounts of objective difference the same
effectiveness upon the mind that, under other circumstances, only large
ones would have.
That 'practice makes perfect' is notorious in the field of motor
accomplishments. But motor accomplishments depend in part on sensory
discrimination. Billiard-playing, rifle-shooting, tight-rope-dancing
demand the most delicate appreciation of minute disparities of
sensation, as well as the power to make accurately graduated muscular
response thereto. In the purely sensorial field we have the well-known
virtuosity displayed by the professional buyers and testers of various
kinds of goods. One man will distinguish by taste between the upper and
the lower half of a bottle of old Madeira. Another will recognize, by
feeling the flour in a barrel, whether the wheat was grown in Iowa or
Tennessee. The blind deaf-mute, Laura Bridgman, so improved her touch as
to recognize, after a year's interval, the hand of a person who once had
shaken hers; and her sister in misfortune, Julia Brace, is said to have
been employed in the Hartford Asylum to sort the linen of its
multitudinous inmates, after it came from the wash, by her wonderfully
educated sense of smell.
The fact is so familiar that few, if any, psychologists have even
recognized it as needing explanation. They have seemed to think that
practice must, in the nature of things, improve the delicacy of
discernment, and have let the matter rest. At most they have said,
"Attention accounts for it; we attend more to habitual things, and what
we attend to we perceive more minutely." This answer, though true, is
too general; but we can say nothing more about the matter here.