il or paper and is requested to give his
solution orally as he works it out. It is then possible to make a
complete record of the method employed.

The subject is likely to resort to some such method as to "fill the
3-pint vessel two thirds full," or, "I would mark the inside of the
5-pint vessel so as to show where 4 pints come to," etc. We inform the
subject that such a method is not allowable; that this would be
guessing, since he could not be sure when the 3-pint vessel was two
thirds full (or whether he had marked off his 5-pint vessel accurately).
Tell him he must _measure_ out the water without any guesswork. Explain
also, that it is a fair problem, not a "catch."

Say nothing about pouring from one vessel to another, but if the subject
asks whether this is permissible the answer is "yes."

The time limit for each problem is 5 minutes. If the subject fails on
the first problem, we explain the solution in full and then proceed to
the next.

The second problem is like the first, except that a 5-pint vessel and a
7-pint vessel are given, to get 8 pints, the subject being told to begin
by filling the 5-pint vessel.

In the third problem 4 and 9 are given, to get 7, the instruction being
to "begin by filling the 4-pint vessel."

Note that in each problem we instruct the subject how to begin. This is
necessary in order to secure uniformity of conditions. It is possible to
solve all of the problems by beginning with either of the two vessels,
but the solution is made very much more difficult if we begin in the
direction opposite from that recommended.

Give no further aid. It is necessary to refrain from comment of every
kind.

SCORING. _Two of the three_ problems must be solved correctly within the
5 minutes allotted to each.

REMARKS. We have called this a test of ingenuity. The subject who is
given the problem finds himself involved in a difficulty from which he
must extricate himself. Means must be found to overcome an obstacle.
This requires practical judgement and a certain amount of inventive
ingenuity. Various possibilities must be explored and either accepted
for trial or rejected. If the amount of invention called for seems to
the reader inconsiderable, let it be remembered that the important
inventions of history have not as a rule had a Minerva birth, but
instead have developed by successive stages, each involving but a small
step in advance.

It is unnecessary to emphasize at length the functio