(i) The "general factors" in intelligence are the same as the
instincts.

(j) Feeble-minded individuals include all those who are below
the average intelligence.

3. It is found that eminent men very often have eminent brothers,
uncles and cousins. How would this fact be explained?

4. It is also found that the wives of eminent men often have eminent
relatives. How would this fact be explained?

5. How could it happen that a boy of 9, in the third school grade,
with an IQ of 140, should be mischievous and inattentive? What
should be done with him?

6. If a boy of 12, by industrious work, does pretty well in the
fourth grade, why should we not accept the teacher's estimate of
him as a "fairly bright boy"?

7. How might the brain of an idiot be underdeveloped, aside from
the matter of the number of nerve cells in the cortex?

8. Can it be that high intelligence is a disadvantage in any form
of industrial work, and, if so, how?

9. Show how "general intelligence" and "special aptitudes" may
work together to give success in some special line of work.

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REFERENCES

For the Binet tests and some results obtained by their use, see Louis
M. Terman, _The Measurement of Intelligence_, 1916.

The group tests used in the American Army during the War are described
in detail In Vol. 15 of the _Memoirs of the National Academy of
Sciences_, 1921, edited by Robert M. Yerkes. This large book describes
the work of preparing and standardizing the tests, and also gives some
results bearing on the Intelligence of different sections of the
population. Some of the interesting results appear on pp. 507, 522,
528, 537, 693, 697, 705, 732, 743, 799, 815, 819, 829, 856 and 869.

For briefer treatments of the subject, see Walter S. Hunter's _General
Psychology_, 1919, pp. 36-58, and W. B. Pillsbury's _Essentials of
Psychology_, 2nd edition, 1920, pp. 388-407.

For the poor results obtained in attempting to judge intelligence from
photographs, see an illustrated article by Rudolph Pintner, in the
_Psychological Review_ for 1918, Vol. 25, pp. 286-296.

For a study of one of the special aptitudes, see C. E. Seashore's
_Psychology of Musical Talent_, 1919.

For a comprehensive survey of test methods and results, see the two
volumes of Whipple's _Manual of Mental and Physical Tests_, 2nd
edition, 1914, 1915.

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CHAPTER XIII

LEARNING AND HABIT FORMATION

THE DEPENDENCE OF A