(^ilycogen, the form in which digested su;.?ar is stored in the body,
disappears. Fatigue, which is due to excessive contractions of muscles,
i- chemically the loss of glycogen and the abnormal presence of these
by-products. As a steam engine will cease to run when the coal is
exhausted or when th^- grates are choked with ashes, so a muscle
becomes fatigued when the glycogen is used up or the muscle is
poisoned by the waste products of its combustion.

Whether work is fatiguing or not depends largely upon whether
the blood can sup; ly glycogen fast enough to supply the working
muscle and at the same time remove the waste products. The faster
the muscles are o;>eratin3, the greater the load upon the heart, lungs
and blood, and the quicker fatigue will appear. Recently, experiments
have demonstrated that the establishment of short rest periods thruout
the working hours tends to lessen fatigue and so permit of a greater
amount of work being done. The wheelbarrow men, mentioned in
Lesson i, who could do more work by working twelve minutes and
resting three minutes in every fifteen minutes, instead of working
steadily all day, illustrated this fact. The principle is now well recog-
nized in industry and is being utilized by many firms.

As so-called mental work seldom calls for a steady, rapid use of any
set of muscles, the rest-period principle hardly applies to it as it does
to hard physical labor. A recess period every hour or two is probably



208



INTRODUCTORY PSYCHOLOGY FOR TEACHERS



all that is necessary to rest the large muscles which are engaged in
supporting the body while one is reading or writing. Experin>ental
studies of fatigue from mental work show that the amount of fatigue
is very small. For example, "Heck* gave tests to school children at
four periods during the day — between 9 A. M. and 9.30 A. M.,
between 11 A. M. and 11 :30 A. M., shortly after i P. M., and about
2.30 P. M. It appears from this experiment that the amount of work
done is increased in the later periods, while the accuracy decreased,
but there does not appear to be any large decrease in efficiency due
to fatigue."** Table XV shows typical results from one school.
TABLE XIV. SHOWING ARRANGEMENT OF EIGHT CHILDREN AC-
CORDING TO THEIR INNATE ABILITY IN ADDITION (B-TEST)
AND MULTIPLICATION (BX-TEST) AND THE TWO SETS
TAKEN TOGETHER





PERIODS


9.00 A. M.


11.00 A. M.


1.30 P. M.


2.30 P. M.


AmcMint done
Accuracy




100
100


100.72
96.69


103.63
95.64


101.10
96.38



The real problem in the school-room is not fatigue, but ennui, lack
of interest. As Thorndike has repeatedly affirmed, children have too
little to do rather than too much. They are not supplied with material
to keep their minds and bodies busy. Any adult who has attempted
to play with children knows how impossible it is to tire them out.
They can keep on the jump from morning to night, or build blocks,
or paste in a scrap book as assiduously as any adult, when they
v;ant to.

EXHAUSTION

Fatigue is a perfectly normal process. It may be defined,
according to Thorndike, as "that diminution in efficiency which
rest will cure."t Exhaustion, on the other hand, is a loss of efficiency
which ordinary rest will not cure. In cases of exhaustion, not onl>
is the glycogen used up, but also part of the muscular structure itself.
In consequence, it takes a comparatively long time for one to recover
from the eflFects of exhausting work.

Exhaustion is present in the case of many persons who are forced
by circumstances to work harder and for longer hours than they can
really stand. Its elimination is an important industrial and social

•W. H. Heck. A Study of Mental Fatigfue in Relation to the Daily School Prorram.
Psylchological CUnlc, Vol. 7. 1913-14, pp. 29-34 and 258-260.

••QuotationB and Table XV from F. N. Freeman, How Children Learn, 1917, p. 289.
tE. L. Thorndike. Educational Psycholovy, Vol. 111. 1914, p. 112.



LESSON 38 209

problem. But fear of exhaustion, on the other hand, does still more
harm, for it prevents men and women from exerting themselves as
they should and robs them of the success they might otherwise achieve.
Aside from worry, a most fatiguing performance, very few of those
directing their own activities ever exhaust themselves. It is normal
to go to bed fatigued. Sufficient sleep should cure fatigue and fit
us for another strenuous day. Happy is the man, like Roosevelt, who
finds his greatest pleasure in activity.

WHAT IS A RESPONSE?

The term "response" has meant so far all those details of an
mdividual's action which result from some situation affecting him.
It is well now to consider the term in greater detail. A response
consists of movements of muscles. But the muscles may be those
that (a) move parts of the body, as the arm, leg, head, etc., or (b)
affect the internal organs, as the heart, the stomach, the various glands,
etc. The first type we are all more or less familiar with, since we are
continually and consciously making such movements and are observing
them in others. The second type we are not conscious of ordinarily.
But they play an equally important part in our life. In the quotation
in Lesson i from "Wednesday Madness," we read "Sam started
violently" in response to Penrod's "Sam-my and May-bul." And
**Mabel ceased to swing her foot, and both, encamadined, looked up."
The "starting violently" and becoming "encarnadined" are evidences
we may note in another of emotional excitement — a term covering
movements of the inner organs. And these responses are more sig-
nificant in this case than "ceasing to swing her foot" and "looking up."

It is related that if a cat is quietly eating her dinner under a table
and sees a strange dog enter the room, that she will cease eating, her
fur will stand on end, her tail will rise erect, she will crouch and
as-sume the best possible position to flee or fight according to circum-
stances. This is all we can see as to her response to the dog's presence.
But careful studies have shown that even if the dog leaves the rootn
without seeing her and she returns to eating that her digestive organs
v.ill not resume their activity for 15 to 20 minutes. The response
to the dog's presence on the part of the inner musculature was to
increase the heart's action, to expand the breathing area of the lungs.
to constrict the blood vessels in the viscera and dilate those in the
muscles, thus driving the blood into circulation between heart, lungs
and muscles, to affect certain glands which give off chemicals, further
increasing the above effects and even affecting the blood so if the
cat is wounded the blood will coagfulate more quickly, etc. And these
effects do not immediately cease when the situation changes.



2IO INTRODL'CTORY PSYCHOLOGY FOR TEACHlvKS

The above illustrates what takes place under the general heading
of emotion. Human beings are affected in a similar manner. And,
apparently, all emotions atfect us in much the same way, whether they
be of fear or joy, of love or hate.

In selling, for example, it is as important to realize that the
prospective buyer will react to the sales talk by tones of voice, expres-
sion of the face and movements, as by words of mouth. And such
responses, when proporly interpreted by the salesman, are more
helpful in determining what his prospect is really thinking than what
he says. For the buyer can hardly control movements showing eager-
ness or irritation, although he may restrain any spoken indication of
his attitude.

A response may consist, further, in a train of thought, in the formu-
lation of a decision, or in an atiitude. The latter we sav/ clearly in
the mirror-drawing experiment, where some assumed a self-attentive
attitude and others did not. But such purely "mental" responses are
accompanied by muscular movements, although they may at times
l>o very slight or seemingly of no connection with the mental processes.
One only has to watch carefully a person who pretends to be con-
temptuous of one's teasing to discover slight twitchings at the corner
of the mouth, or tapping with the foot, etc. — all signs that the teasing
is being reacted to.

When one suddenly comes upon a covey of young quail, there is
immediately a tremendous fluttering in the brush and then an absolute
quiet. The young birds have reacted to the situation of a man's
presence by running to cover and then remaining absolutely still. The
lack of movement is as much a part of the response as the scurrying
to cover. Here is inhibition of movement as a type of response.
Careful examination of the young birds while playing 'possum would
indicate emotional activity, so that this lack of movement is not
complete but only of those muscles pertaining to movements of limbs
and body.

In every-day life we are much more likely to overlook responses to
n situation which cause lack of bodily movement than of responses
v.'here the individual do's something. Sometimes the absence of
movement, when ordinarily movement is to be expected, is just the
response to be noted. For example, candy having disappeared from
a table drawer, three children are suddenly confronted with the
ouestion, "Who took the candy?" Two chorus out "Not me! What
candy?" The third, after ten seconds, in a more subdued voice,
responds "Not me." The temporarily inhibited reply and the entire



LESSON 39 211

absence of interest in "what candy" clearly prove the presence of
important elements in the situation to which the third child is responding
tl'at are absent in the case of the other two.

Interference between two responses to the same situation is some-
times the cause of no response to a situation. For example, as in
Lesson 17, an individual might have responded to the letter "m" by
the numeral "47," since "m" was shown with "47" three times. But if
"m" had also been shown with "12," this same individual would quite
likely make no response to the letter "m." Closer observation of him
would have shown signs of irritation, for failure to respond due to
interference of bonds is usually accompanied by emotional disturbance.

The response is the sum total of the behavior brought about hv a
situation affecting an individual. It includes movements produced by
the large muscles of the body or of the small muscles within the body,
and the total of consciousness involved therein.

RIvFERIvN'CES

W. H. Howell, A Text-book of Physiology, 1907, Chaps. I and 11.
Ladd and Woodworth, Physiological Psychology, 191 1, pp. 536-541.
P. C. Stiles, The Nen'ous System and Its Conservation, 1914.

LESSON 39. HOW DOES ONE ESTIMATE DISTANCE?

In Lesson ^y we discovered that the visual impressions received by
the two eyes are not identical. And the same fact was discovered
concerning two sterescopic pictures. Moreover, we ascertained that
there was a greater difference between those details of pictures which
were in the foreground than between those in the background. Depth
or perspective is clearly added to a picture when two views thus con-
structed are seen together. How is this accomplished?

The two eyes must rotate more (converge) when fixated on a near
object than on a distant object. From experience, we have learned
v/hen we fixate on a string attached to a window curtain that (a) it
is this string (not some other object) and (b) it is about so far from
us. The object aspect of the response is due to stimulation of the
retina by waves of light from the string, which in turn transmits a
stimulation over the optic nerve to the brain. The distance aspect is
due to the kinaesthetic sense-organs in the muscles that rotate the eye
in order to fixate it on the string. They are stimulated to a certain
extent and this stimulation is also transmitted over the nerve to the
brain. There these particular stimulations cause us quite unconsciously
to add to the object- aspect the idea of the string being located so far
from us. The total perception — string so far from us — is a fusion,
then, of visual and kinaesthetic stimulations.



212 INTRODUCTORY PSYCHOLOGY FOR TEACHERS

Photographs taken for a stereoscope are taken by two cameras
placed side by side but somewhat farther apart than the distance
between the two eyes. The photographs over-emphasize the dif-
ference in the two views as seen by the two eyes. When placed in a
stereoscope, one must converge his eyes more in order to have both
eyes fixated on near objects than on distant objects in the two pictures.
Consequently, we think (^f them as nearer because always in life when
we have to converge our eyes upon an object it is nearer than an object
which requires less convergence.

The above is the explanation of how in binocular vision we deter-
mine distances up to loo feet. At loo feet the eyes are both fixated
straight ahead. Consequently there can be no greater divergence for
objects beyond this distance than for lOO feet and, accordingly, we
can not estimate distances beyond this distance on the basis of
convergence and divergence.

Now how do we estimate distance up to 6 feet with monocular
vision, and, second, how do we estimate distance beyond lOO feet?
It is perfectly apparent that we can do both these things.

EXPERIMENT

Problem: What are the Factors Underlying the Perception of
Distance? (Continued.)

Apparatus. Three pins.

Procedure :

(i) Have S close one eye and then have him note the changes
that occur in the appearance of a pencil and the resulting sensations
in the eye as E moves a pencil towards and away from the eye within
the limits of an inch and six feet. Is S ever at a loss to know just
iiow far the pencil is from him?

(2) In order to determine how accurate is S's ability to estimate
relative distances, stick two pins into the far end of a table, say six
feet from S. The line of the two pins should be perpendicular to S's
line of vision. Now place the third pin between the other two some-
times in front of them and sometimes behind them and ascertain how
accurately S can determine the relative distance of the middle pin
as compared with the two outside pins. When this has been done,
repeat the experiment, S using only one eye.

Just as a camera has to be adjusted for focusing on near and distant
objects, so the lens of the eye has to be correspondingly adjusted.
As has been pointed out in Lesson 36, these adjustments are made
by contractions or relaxations of the ciliary muscle which is attached
to the lens. Located in and about the ciliary muscle are kinaesthetic
sense-organs. Ordinarily we are unconscious of the sensations



LESSON 40 213

aroused by these sense-organs. But when the pencil is broughi clo>e
to the eye, the strain in the ciliary muscle, in order to secure a clear
focus, is so unusual that we notice it. Altho we are not ordinarily
conscious of the kinaesthetic sensations caused by movements in the
ciliary muscles, yet we act in terms of them. That is, thru experience
we have learned that when the eyes are focused on a very near object,
the ciliary muscle is under a certain strain, whereas when the object
is farther away this strain is different. Consequently when confronted
by an object, the first reaction is to focus it on the retina (a reflex act
unconsciously done). We then receive (a) visual stimulations from
the object which give us our knowledge of the object and (b) kinaes-
tlietic stimulations from the ciliary muscle which give us our knowl-
edge of the distance of the object from the eye. Rather the two —
visual and kinaesthetic — sensations fuse together and we perceive
such and such an object at such and such a distance. The above
mechanism is an aid to us in estimating short distances of say six feet
and less.

(3) Can an individual blind in one eye utilize the factors involved
in binocular vision in estimating distance? Recall the details dis-
covered in Lesson 37, part 2, with the books C and D. Note also in
the same way, but with one eye, the differences in the view of book D
obtained by swinging the head from side to side.

Repeat the above procedure, but, instead of moving the head from
side to side, walk from your window to the next and note such changes
as may occur in the view of objects at a considerable distance from you.

(4) Finish up your study of the other factors involved in the
e.stimation of the distance of objects over 100 feet away.

Results: Report your results in the best way you know to bring out
the principal points of the experiment.

Questions: (i) In what way does one estimate distances up to
six feet?

(2) In what way does one estimate distances of from 6 to 100 feet?

(3) In what way does one estimate distances over 100 feet? Con-
sider also the followinj:^ questions in this connection :

a. If one did not know the size of an object, say a low hill, would
that affect his estimation of its distance? Why? Explain.

b. Is the same distance estimated differently on a foggy dav
from what it is on a dear one? Why do Easterners underestimate
distance in Colorado?

C. Do differences in color affect the estimation of distance?
How? Why?



214 INTRODUCTORY PSYCHOLOGY FOR TEACHERS

d. \\ hich is easier to estimate the distance of, (a) a man walking;-

along a road, (b) an auto, (c) a train along a railroad track, or

(d) an aeroplane in the air? Why? How is the estimation made?
e. What part can a shadow play in the estimation of distance?

Application:

Write up your experiment and hand it in at the next class-hour.

REFERENCES

G. M. Stratton, Experimental Psychology and Culture, 1903,
Chapters VII, VIII.

W. B, Pillsbury, Attention, 1908, Chapter V.

J, R. Angell, Psychology, 1908, pp. 172-190.

E. B. Titchener, Experimental Psychology, Qualitative, Student's
Manual, 1909, pp. 137-151.

E. B. Titchener, Experimental Psychology, Qualitative, Instructor's
Manual, 1909, pp. 228-303.

W. B. Pillsbury. Essentials of Psychology, 191 1, pp. 162-171,

G. T. Ladd and R. S. Woodworth, Physiological Psychology, 191 1,

pp. 413-431-

It is not necessary, nor is it expected of students, to consult these
references in writing up the experiment. They are listed here for the
use of any who are interested and wish to devote extra time to the
subject.



LESSON 40. - THE MECHANISM OF THE CONNECTING
SYSTEM. THE NERVOUS SYSTEM*

We now have a fair conception of how a sense-organ is stimulated
into activity by outside agencies. We also realize that when a muscle
or a group of muscles is stimulated, it contracts and moves a portion
of the body. And, from the illustrations given in Plates XXX and
XXXI, we have obtained a general notion as to how the stimulation
received in the sense-organ is finally transmitted to the muscles and
they in turn react. In those three examples we have cases in which
the current flows from the skin to the muscle (a) by way of the
spinal cord, (b) by way of the mid-brain, and (c) by way of the
cortex of the brain. About these three examples we can build a great
deal of the total conception that is necessary in understanding the
connecting- system.

The first three points to get clear in understanding the nervous
system are : First, sense-organs are connected unth muscles by way
cf a central station in the spinal cord, mid-brain, or cerebrum.
Second, the nervous system is made tip of these three centrals together
with nerve-fibres running to the sense-organs and to the muscles of
the body. Third, the function of the nervous system is to connect
sense-organs tvith muscles.

In order to obtain a clearer, more accurate conception of the con-
nections which are made possible by the nervous system, it will be
necessary to obtain a better notion of the anatomy of the nervous
system.

THE NEURONE

The nervous system can be roughly divided into four parts : ( i )
The spinal cord, (2) the mid-brain, (3) the cerebrum, and (4) the
i^erves that connect these parts with sense-organs and muscles. .\11
of these four parts are composed of something like 11,000,000,000
nerve-cells combined in various ways.

The neurone. In Plate XXXIV are shown six different nerve -
cells or neurones as they are more often called. At first glance they
do not look much alike. A closer study will show that they all have
certain characteristics in common. Each nerve-cell has ( i ) a cell-body
and (2) certain projections from the cell-body called filaments. The
cell-bodv is compo.sed of protoplasm and has a nucleus. The filaments



•CLASS-HOUP


IN CLASS 1


WRITE-UP


- ■'■

READ


40
41
42
43
44


Discuss, Les. 38, 39
Discuss, Les. 40
Discuss, Les. 41

Review. Les. 34-41
Examination




Lesson 40

Lesson 4 t

Review, Les. 34 41

Review

1



M5



2l6 INTRODUCTORY PSYCHOLOGY FOR TEACHERS

can be divided into two kinds : the axon and the dendrites. A nerve-
cell has one axon but it may have many dendrites. The axon can be
likened to a cable of telephone wires. It is made up of many fibrils
similar possibly to the separate wires in the cable. Around these are
one or two sheaths, possibly of an insulating character but more
probably for the puriX)se of supporting and nourishing the fibril core.
Axons may be infinitesimally short or up to five feet in length in man.
Ordinarily they have few subdivisions. A bundle of such axons make
up a nerve. The other type of filament, the dendrite, is usually quite
short and much branched, often suggesting a bush.

The neurone has certain characteristics in common with all living
cells. It is irritable, by which is meant that it responds to certain
stimulations. It {)ossesses conductivity, by which is meant that a
stimulation at one point of its body is transmitted to any other part
of its body. Besides these two, it probably has also the function of
either reinforcing or inhibiting the impulse communicated to it. To
illustrate the reinforcing function, consider the fact that a relatively
slight pull on the trigger of a gun will produce a relatively great
response. The stored-up energy in the cartridge is set off at the
slight impact. In somewhat the same way a nerve-cell may be only
slightly stimulated but it may respond in such a way as to stimulate
verv much more stroni^ly the next cell in the series. The neurone as
a whole then receives and transmits stinnilations and in doing so may
increase or decrease the intensity of the stimulation.

Turning now to the functions of the various parts of the neurone,
we must note that '"the cell-body has the highly important function of
serving the nutrition of the whole neurone ; it is necessary for main-
taining the axon and dendrites in proper condition for work, even tho
it may take no peculiar part in the actual doing of the work."*

The axon carries impulses away from the cell-body, while the den-
drites receive impulses from without and transmit the stimulation
toward the axon. In thinking of the neurone as a link in the chain
connecting a sense-organ* and muscle, we must always think of the
current first stimulating the end of a dendrite and of it then being
transmitted over the dendrite to the axon and out the axon. The
nervous current never flows in the reverse direction.f

THE SYNAPSE

The sytiapse is the point of contact between an axon and a dendrite.
It is still a debated question whether there is actually a gap between
the axon and dendrite or not. but it is certain that as far as their

• Ladd and Woodworth, Physiological Psychology, 1911, p. 288.

tThe aboTe is true except in the case of the sensory neurones connecting sense-
organs with the spinal cord. Here the axon on leaving the cell-body divides and one
branch goes to the sense-organ and the other into the spinal cord.



LESSON 40



217



function is concerned we may speak of the synaj^se as a functional gap.
From physics we know that a weak electrical current will jump across
a small gap in the form of a series of small sparks, but it will not jump
a large gap. If the strength of the current is increased, the current
will again jump the larger gap in a series of larger sparks. The
smaller the gap, then, the less the resistance and consequently the
smaller the current needed to jump the gap. This conception was
early applied to the synapse. It was supposed that the dendrite and
axon actually moved toward or away from each other and in doing




Plat* XXXIV. A cell from th« spinal ganglion; B, cell from the ventral horn of
•pinal cord; C, cell from the sympathetic, D, cell from the spinal cord; E, pyramidal cell
from the cerebral cortex; F, cell from the cerebellar cortex; a, axones; d, dendrite*;
c, collaterals; p. peripheral part of the fibre; cl, central part. Arrows indicate the