a larger
number of active neurones.

But why should not two equally big brain activities sometimes occur at
the same moment, and attention thus be divided? The only promising
hypothesis that has been offered to explain the absence of divided
attention is that of "neurone drainage", according to which one or the
other of two neurone groups, simultaneously aroused to activity,
drains off the energy from the other, so putting a quietus on it.
Unfortunately, this hypothesis explains too much, for it would make it
impossible for minor brain activities to go on at the same time as the
major one, and that would mean that only one thing could be done at a
time, and that the field of consciousness was no broader than the
field of attention. On the whole, we must admit that we do not know
exactly what the focusing of attention can mean in brain terms.

{270}

EXERCISES

1. Outline the chapter, in the form of a number of "laws", putting
under each law the chief facts that belong there.

2. See if you can verify, by watching another person's eyes, the
statements made on page 250 regarding eye movements.

3. Choose a spot where there is a good deal going on, stay there
for five minutes and jot down the things that attract your
attention. Classify the stimuli under the several "factors of
advantage".

4. Mention some stimulus to which you have a habit of attention,
and one to which you have a habit of inattention.

5. Close the eyes, and direct attention to the field of cutaneous
and kinesthetic sensations. Do sensations emerge of which you are
ordinarily only dimly conscious? Does shifting occur?

6. Of the several factors of advantage, which would be most effective
in catching another person's attention, and which in holding his
attention?

7. How does attention, in a blind person, probably differ from that
of a seeing person?

8. Doing two things at once. Prepare several columns of one-place
numbers, ten digits in a column. Try to add these columns, at the
same time reciting a familiar poem, and notice how you manage it,
and how accurate your work is.

9. Consider what would be the best way to secure sustained
attention to some sort of work from which your mind is apt to wander.

REFERENCES

Walter B. Pillsbury gives a full treatment of the subject in his book
on _Attention_, 1908, and a condensed account of the matter in Chapter
V of his _Essentials of Psycholo