basis of tests, sense-impressions which are unfamiliar to all. The conditions of the tests should be
simple, easily intelligible, and, if possible, interesting, so as to induce on the part of the subject a
willing coöperation, a natural attitude and a desire to do his best. The tests must occupy as short a
time as possible, the apparatus be not easily disarranged by unskilled handling, not too expensive,
and, in brief, be practically efficient.
Passing to details the question of method is preëminent; this obviously differs essentially with the
various types of tests. For the limits of sense capacity-sensitiveness-as determined by the minimum
visible, the minimum audible, the minimum tangible, the question of method is substantially the
question of experimental conditions, choice of apparatus and material. For the powers of discerning
small differences between similar sense-impressions-sensibility-the methods are various and have
been the subject of considerable controversy, some of which has become of historical interest. The
question must be [p. 174] reconsidered in the light of popular, practical requirements, and, first of all,
the necessity of securing a definite, even if not precise, result in a brief time. The method of
reproducing a standard sense impression-involving in its calculation of results the determination of
the average error-may be highly recommended as satisfying the requirement; but it is unfortunately
not readily applicable to all the senses, being most naturally serviceable in the case of those senses
which receive impressions quickly and pass readily from one sense impression to another. Ingenuity
in arranging the apparatus may do much to minimize this disadvantage. The best substitute for the
method of reproduction is the method of selection, the subject selecting one of a given series of
sense-impressions arranged in orderly sequence as the equivalent of the standard impression. Of
the two other most frequently employed methods, commonly known as the method of right and
wrong cases, and of the just observable difference, the former occupies too much time and the latter
is too vague in its results. These methods may be variously modified to make them more suitable,
as, for instance, the method of arranging a group of sense-impressions in their true order of size or
degree, but the difficulty of interpreting the degree of error of the results thus obtained seems to
outweigh their other advantages. Sensory tests may involve distinctions of kind as well as of degree,
and in these the element of time as well as correctness may be profitably utilized as a criterion of
efficiency. This is particularly applicable to distinctions of form and color.
In regard to motor tests, method is again mainly a question of the choice of apparatus and of the
groups of muscles to be tested. The qualities of motor response of greatest importance in this
connection are strength, which may mean the maximum efficiency at a given moment, or may mean
endurance, rapidity of muscular contraction, steadiness or precise voluntary control, accuracy of
movement both in itself and in coordination with the eye. The muscle groups to be selected are
those which are frequently and familiarly used and easily subject to voluntary control.
The more complex mental tests form a somewhat heterogeneous group. Many of those which are
apt to be considered in a popular investigation will involve in various ways a series of more or less
complicated distinctions, and of appropriate responses to or modes of indicating the appreciation of
such distinctions; while another group arises to test certain phases of memory, or association, or
attention or imagination. The former group would be naturally termed reactions, [p.175] the time
element or alertness furnishing the main test. Typical simple reactions to show the quietness of
appreciations of the presence of a stimulus, and a sufficient variety of adaptive reactions to indicate
clearly the strength of the powers of distinction and of choice, should form a part of the test. Here,
perhaps, more than elsewhere, the adoption of suitable standards is essentially dependent upon
coöperative effort. Here, too, the question of apparatus and material is of unusual importance; first,
because apparatus for timing is apt to become elaborate, and, second, because the naturalness of
the mental processes involved in the test is a function of the details of arrangement. Little can be
said as yet of the tests of memory, attention, association, imagination and the like. They are
eminently desirable, but in part seem to involve more accurate conditions than it is usually
practicable to secure. The most hopeful plan is to have different investigations take up extensive
series of tests of special forms of the above powers and let actual experience decide as to their
merits.
These remarks are offered by way of a summary discussion of principles underlying the selection of
specific tests; their application to the problems of mental anthropometry, now at issue, is a task to
the solution of which, it is hoped, that the members of the committee, as well as others, will
contribute in the near future.
Professor Baldwin remarked upon the need of giving the tests as psychological a character as