Part 6 (1/2)

Thus we take a glance out of theand say that the day looks cold, although ell know that we cannot see _cold_ Or we say that the h a _crack_ or _greenness_ cannot be heard Or we say that the box feels eh _emptiness_ cannot be felt We have coinally experienced with days which look like the onesee, with this particular appearance, and so we say we see the cold; sounds like the one co from the bell we have co froly that the bell sounds cracked and the reen

And so with the various senses Each gleans froe, but all are finally in a partnershi+p and what is each one's knowledge belongs to every other one in so far as the other can use it

THE SENSORY PROCESSES TO BE EXPLAINED--The explanation of the ultih contact with our material environh they have over the question, and still others they will have before the matter is settled The easier and more important problem for us is to describe the _processes_ by which the mind comes to know its environ This much we shall be able to do, for it is often possible to describe a process and discover its laws even e cannot fully explain its nature and origin We know the process of digestion and assih we do not understand the ultiin of _life_ which makes these possible

THE QUALITIES OF OBJECTS EXIST IN THE MIND--Yet even in the relatively simple description which we have proposed many puzzles confront us, and one of them appears at the very outset This is that the qualities which we usually ascribe to objects really exist in our own minds and not in the objects at all Take, for instance, the coht and color The physicist tells us that e see as light is occasioned by an incredibly rapid beating of ether waves on the retina of the eye All space is filled with this ether; and when it is light--that is, when so body is present--the ether is set inht, its waves strike the retina, a current is produced and carried to the brain, and we see light This means, then, that space, the ht (the sensation), but with very rapid waves of ether, and that the light which we see really occurs in our own minds as the mental response to the physical stimulus of ether waves Likeith color Color is produced by ether waves of different lengths and degrees of rapidity

Thus ether waves at the rate of 450 billions a second give us the sensation of red; of 472 billions a second, orange; of 526 billions a second, yellow; of 589 billions a second, green; of 640 billions a second, blue; of 722 billions a second, indigo; of 790 billions a second, violet What exists outside of us, then, is these ether waves of different rates, and not the colors (as sensations) themselves The beautiful yellow and criated colors of a landscape, the delicate pink in the cheek of a child, the blush of a rose, the shi+reen of the lake--these reside not in the objects themselves, but in the consciousness of the one who sees the back to the eye ether waves of the particular rate corresponding to the color which we ascribe to them Thus ”red” objects, and no others, reflect back ether waves of a rate of 450 billions a second: ”white” objects reflect all rates; ”black” objects reflect none

The case is no different with regard to sound When we speak of a sound co from a bell, e really mean is that the vibrations of the bell have set up waves in the air between it and our ear, which have produced corresponding vibrations in the ear; that a nerve current was thereby produced; and that a sound was heard But the sound (ie, sensation) is a , and exists only in our own consciousness

What passed between the sounding object and ourselves aves in the intervening air, ready to be translated through the machinery of nerves and brain into the beautiful tones and melodies and harmonies of the mind And so with all other sensations

THE THREE SETS OF FACTORS--What exists outside of us therefore is a _stiy, of a kind suitable to excite to activity a certain end-organ of taste, or touch, or s; what exists within us is the _nervousthis stimulus into a nerve current which shall produce an activity in the cortex of the brain; what results is the _mental object_ which we call a _sensation_ of taste, s

2 THE NATURE OF SENSATION

SENSATION GIVES US OUR WORLD OF QUALITIES--In actual experience sensations are never known apart fro

This is to say that e see _yellow_ or _red_ it is always in connection with some surface, or object; e taste _sour_, this quality belongs to some substance, and so on with all the senses Yet by sensation we mean only _the simple qualities of objects known in consciousness as the result of appropriate stians_ We shall later see how by perception these qualities fuse or combine to form objects, but in the present chapter we shall be concerned with the qualities only Sensations are, then, the siet from the physical world,--the red, the blue, the bitter, the cold, the fragrant, and whatever other qualitiesto the external world We shall not for the present be concerned with the objects or sources from which the qualitiesof sensation: ”All we can say on this point is that _e s in the way of consciousness_ They are the _immediate_ results upon consciousness of nerve currents as they enter the brain, and before they have awakened any suggestions or associations with past experience But it is obvious that _such immediate sensations can be realized only in the earliest days of life_”

THE ATTRIBUTES OF SENSATION--Sensations differ from each other in at least four respects; namely, _quality_, _intensity_, _extensity_, and _duration_

It is a difference in _quality_ that makes us say, ”This paper is red, and that, blue; this liquid is sweet, and that, sour” Differences in quality are therefore fundamental differences in _kind_ Besides the quality-differences that exist within the saeneral field, as of taste or vision, it is evident that there is a stillbetween the various fields One can, for example, compare red with blue or sith sour, and tell which quality he prefers But let him try to compare red with sweet, or blue with sour, and the quality-difference is so profound that there seems to be no basis for comparison

Differences in _intensity_ of sensation are faar rather than one lump in his coffee; the sweet is of the same quality in either case, but differs in intensity In every field of sensation, the intensity reatest aeneral, the intensity of the sensation depends on the intensity of the stiards fatigue or adaptation to the stimulus has its effect It is obvious that a stimulus may be too weak to produce any sensation; as, for exaar in a cup of coffee or a few drops of lemon in a quart of water could not be detected It is also true that the intensity of the stireat that an increase in intensity produces no effect on the sensation; as, for exaar to a solution of saccharine would not noticeably increase its sweetness The lowest and highest intensity points of sensation are called the lower and upper _limen_, or threshold, respectively

By _extensity_ is meant the space-differences of sensations The touch of the point of a toothpick on the skin has a different space quality from the touch of the flat end of a pencil Low tones seeh tones Some pains feel sharp and others dull and diffuse The war the palness” not felt froer The extensity of a sensation depends on the nus stimulated

The _duration_ of a sensation refers to the time it lasts This must not be confused with the duration of the stier or shorter than the duration of the sensation Every sensationor short, or it would have no part in consciousness

3 SENSORY QUALITIES AND THEIR END-ORGANS

All are faies, sight, hearing, taste, smell, and touch A more complete study of sensation reveals nearly three times this number, however This is to say that the body is equipped with ans, each prepared to receive its own particular type of stians yield ives not only visual but muscular sensations; the ear not only auditory, but tactual; the tongue not only gustatory, but tactual and cold and warmth sensations

SIGHT--Vision is a _distance_ sense; we can see afar off The stimulus is _chemical_ in its action; thisthe retina, cause a chee which sets up the nerve current responsible for the sensation

The eye, whose general structure is sufficiently described in all standard physiologies, consists of a visual apparatus designed to bring the ies of objects to a clear focus on the retina at the _fovea_, or area of clearest vision, near the point of entrance of the optic nerve

The sensation of sight coives us but two qualities, _light and color_ The eye can distinguish h the various grays to densest black The range is greater still in color

We speak of the seven colors of the spectrue, and red But this is not a very serviceable classification, since the average eye can distinguish about 35,000 color effects It is also so to find that all these colors seereen, yellow, and blue, plus the various tints These four, corees of light (ie, different shades of gray), yield all the color effects known to the human eye Herschel estimates that the workers on the uished 30,000 different color tones The _hue_ of a color refers to its fundamental quality, as red or yellow; the _chroth of the color; and the _tint,_ to the ahtness (ie, white) it contains

HEARING--Hearing is also a distance sense The action of its stimulus is mechanical, which is to say that the vibrations produced in the air by the sounding body are finally transmitted by the mechanism of the middle ear to the inner ear Here the ih the liquid of the internal ear to the nerve endings as so many tiny blohich produce the nerve current carried to the brain by the auditory nerve

The sensation of hearing, like that of sight, gives us two qualities: na pitch and timbre, and _noises_