y and seems
heavy.

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EXERCISES

1. Outline the chapter.

2. Show that the law of combination accounts both for many
correct perceptions, and for many illusions.

3. Through which of the senses are spatial facts best perceived?

4. "At first, the baby very likely perceives a ball simply as something
for him to handle and throw; but, through the medium of blocked
response, he comes to perceive it more objectively, i.e., as an
object related to other objects, and not simply related to
himself." Explain and illustrate this statement.

5. Give an example from the field of auditory perceptions where
"isolation" is very much in evidence.

6. Can you see any law analogous to Weber's law in the field of
financial profit and loss? Does a dollar gained or lost _seem_ the
same amount, without regard to the total amount possessed?

7. Trial and error perception. Go about the room with closed eyes,
and identify objects by touching them with the hands. Notice
whether your first impression gives place to corrected impressions.

8. Perception of form by "active" and "passive" touch. With
the eyes closed, try to distinguish objects of different shapes (a)
by letting them simply rest upon the skin, and (b) by handling
them. What senses cooeperate in furnishing data for "active touch"?

9. Binocular parallax, or the differing views of the same solid object
obtained by the two eyes. Hold a small, three-dimensional object a
foot in front of the face, and notice carefully the view of it
obtained by each eye separately. A pencil, pointing towards the
face, gives very different views. What becomes of the two monocular
views when both eyes are open at once?

10. Binocular compared with monocular perception of "depth"
or distance away. Take a pencil in each hand, and bring the points
together a foot in front of the face, while only one eye is open.
When the points seem to be nearly touching, open the other eye,
and see whether the two points still seem to be close together.
Repeat.

REFERENCES

Discussions of perception that are in some respects fuller than the
present chapter can be found in C. H. Judd's _Psychology, General
Introduction_, 2nd edition, 1917, pp. 162-194; in Titchener's
_Textbook of Psychology_, 1909, pp. 303-373; and in Warren's _Human
Psychology_, 1919, pp. 232-269.

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CHAPTER XVIII

REASONING

THE PROCESS O