Psychology Part 5

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EXERCISES

1. Outline of the chapter, being at the same time a "completion test". Complete the following outline by filling in the blank s.p.a.ces (usually a single word will fill the blank, but sometimes two words will be better):

A. Definition: A reaction is a response to a ___________.

The stimulus energy stored in the organism, and the __________ has a definite form determined by the organism's own machinery of ________ and ______.

B. Among very prompt reactions are the reflex and the "simple reaction". The reflex differs from the "simple reaction" in that:

(1) It usually takes less________.

(2) It requires no___________,

(3) The machinery for it is ________in the organism.

C. The machinery for a reflex consists of:

(1) a________ organ.

(2) a ________nerve.

(3) a nerve ________,

(4) a _________nerve.

(5) a muscle or _________.

D. The sensory and motor nerves consist of ________ which are branches of ______. The cells for the motor nerves lie in the ________, and those for the sensory nerves lie in two cases in the _________, and in all other cases in bunches located close beside the _________or ________,

E. The neurone is the _______ of which the nervous ______ is composed. It consists of a ________ and of two sorts of branches, the ________ and the ________. Internally, the neurone shows a peculiar structure of ________ and ________.

F. Communication from one neurone to another occurs across a _____ called the synapse. The _________of an axon here comes into close contact with the ______or with the _________of another neurone. The communication takes place from the ________of the first neurone to the ___________ of the second.

G. The "nerve current" in a reflex therefore runs the following course: from the sense organ into a ________ axon, along this to its _________ in a nerve, and across a _________ there into the _________ of a neurone, and thence {43} out along the _______of this neurone to the ________or _________ that executes the reflex. This is a two-neurone _________, but often there is a third, ________neurone between the _________ and the _____________.

H. Coordination is effected by the ________ of the axons of the sensory and ________ neurones, by which means the nerve current is ______ to a team of ________ and so to a team of _________.

2. Is the reaction time experiment, as described in the text, an introspective or an objective experiment?

3. Mention two cases from common life that belong under the "simple reaction", two that belong under "choice reaction", and two that belong under the "a.s.sociative reaction".

4. Arrange the reflexes mentioned in the text under the two heads of "protective" and "regulative".

5. Draw diagrams of (a) the neurone, (b) a synapse, (c) a reflex arc, and (d) a coordinated movement. Reduce each drawing to the simplest possible form, and still retain everything that is essential.

6. What part of the nervous system lies (a) in the forehead and top of the head, (b) in the very back of the head, (c) along the base of the skull, (d) within the backbone, (e) in the arm?

7. Using a watch to take the time, see how long it takes you to name the letters in a line of print, reading them in reverse order from the end of the line to the beginning. Compare with this time the time required to respond to each letter by the letter following it in the alphabet (saying "n" when you see m, and "t" when you see s, etc.). Which of these two "stunts" is more like reflex action, and how, nevertheless, does it differ from true reflex action?

8. The pupillary reflex. Describe the reaction of the pupil of the eye to light suddenly shining into the eye. This response can best be observed in another person, but you can observe it in yourself by aid of a hand mirror. On another person you can also observe the "crossed" pupillary reflex, by throwing the light into one eye only while you watch the other eye. What sort of connection do you suppose to exist between the two eyes, making this crossed reflex possible?

9. The lid reflex, or wink reflex, (a) Bring your hand suddenly close to another person's eye, and notice the response of the eyelid, (b) See whether you can get a crossed reflex here, (c) See whether your subject can voluntarily prevent (inhibit) the lid reflex, (d) See whether the reflex occurs when he gives the stimulus himself, by moving his own hand suddenly up to his eye.

(e) What other stimulus, besides the visual one that you have been using, will arouse the same response?

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REFERENCES

C. Judson Herrick, in his _Introduction to Neurology_, 2nd edition, 1918, gives a fuller and yet not too detailed account of the neurone in Chapter III, and of reflex action in Chapter IV.

Percy G. Stiles, in his _Nervous System and Its Conservation_, 1915, discusses these matters in Chapters II, III and IV.

Ladd and Woodworth's _Elements of Physiological Psychology_, 1911, has chapters on these topics.

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CHAPTER III

REACTIONS OF DIFFERENT LEVELS

HOW SENSATIONS, PERCEPTIONS AND THOUGHTS MAY BE CONSIDERED AS FORMS OF INNER RESPONSE, AND HOW THESE HIGHER REACTIONS ARE RELATED IN THE NERVOUS SYSTEM TO THE SIMPLER RESPONSES OF THE REFLEX LEVEL.

Having defined a reaction as an act of the individual aroused by a stimulus, there is no reason why we should not include a great variety of mental processes under the general head of reactions. Any mental process is an activity of the organism, and it is aroused by some stimulus, external or internal; therefore, it is a reaction.

I hear a noise--now, while the noise, as a physical stimulus, comes to me, my hearing it is my own act, my sensory reaction to the stimulus.

I recognize the noise as the whistle of a steamboat--this recognition is clearly my own doing, dependent on my own past experience, and may be called a perception or perceptive response. The boat's whistle reminds me of a vacation spent on an island--clearly a memory response. The memory arouses an agreeable feeling--an affective response, this may be called. In its turn, this may lead me to imagine how pleasant it would be to spend another vacation on that island, and to cast about for ways and means to accomplish this result--here we have imagination and reasoning, aroused by what preceded just as the sensation was aroused by the physical stimulus.

In speaking of any mental process as an act of the individual, we do not mean to imply that he is always _conscious_ {46} of his activity.

Sometimes he feels active, sometimes pa.s.sive. He feels active in hard muscular work or hard thinking, while he feels pa.s.sive in reflex action, in sensation, and in simply "being reminded" of anything without any effort on his own part. But he is active in everything he does, and he does everything that depends on his being alive. Life is activity, and every manifestation of life, such as reflex action or sensation, is a form of vital activity. The only way to be inactive is to be dead.

But vital activity is not "self-activity" in any absolute sense, for it is _aroused_ by some stimulus. It does not issue from the individual as an isolated unit, but is his _response_ to a stimulus.

That is the sense of calling any mental process a reaction; it is something the individual does in response to a stimulus.

To call a sensation a form of reaction means, then, that the sensation is not something done to the person, nor pa.s.sively received by him from outside, but something that he himself does when aroused to this particular form of activity. What comes from outside and is received by the individual is the stimulus, and the sensation is what he does in response to the stimulus. It represents the discharge of internal stored energy in a direction determined by his own inner mechanism.

The sensation depends on his own make-up as well as on the nature of the stimulus, as is especially obvious when the sensation is abnormal or peculiar. Take the case of color blindness. The same stimulus that arouses in most people the sensation of red arouses in the color-blind individual the sensation of brown. Now what the color-blind individual _receives_, the light stimulus, is the same as what others receive, but he responds differently, _i.e._, with a different sensation, because his own sensory apparatus is peculiar.

The main point of this discussion is that all mental {47} phenomena, whether movements, sensations, emotions, impulses or thoughts, are a person's acts, but that every act is a response to some present stimulus. This rather obvious truth has not always seemed obvious.

Some theorists, in emphasizing the spontaneity and "self-activity" of the individual, have pushed the stimulus away into the background; while others, fixing their attention on the stimulus, have treated the individual as the pa.s.sive recipient of sensation and "experience"

generally. Experience, however, is not received; it is lived, and that means done; only, it is done in response to stimuli. The concept of reaction covers the ground.

While speaking of sensations and thoughts as belonging under the general head of reactions, it is well, however, to bear in mind that all mental action tends to arouse and terminate in muscular and glandular activity. A thought or a feeling tends to "express itself"

in words or (other) deeds. The motor response may be delayed, or inhibited altogether, but the tendency is always in that direction.

Different Sorts of Stimuli