emperamental characteristics,
experience, and affective peculiarities of individuals.

The light which I have obtained on the general problem of ideation has
come, first, through a method which I have rather inaptly named the
multiple-choice method, and second, and more incidentally, through a
variety of supplementary methods which are described in Section IV of
this report. These supplementary methods are simple tests of ideation
rather than systematic modes of research. They differ from my chief
method, among other respects, in that they have been used by various
investigators during the past ten or fifteen years. It was not my aim to
repeat precisely the observations made by others, but instead to verify
some of them, and more especially, to throw additional light on my main
problem and to further the analysis of complex behavior.

What has been referred to as the multiple-choice method was devised by
me three years ago as a means of obtaining strictly comparable objective
data concerning the problem-solving ability of various types and
conditions of animals. The method was first tried with human subjects in
the Psychopathic Hospital, Boston, with a crude keyboard apparatus
which, however, proved wholly satisfactory as a means of demonstrating
its value. It has since been applied by means of mechanisms especially
adapted to the structure and activities of the organisms, to the study
of the behavior of the crow, pig, rat, and ringdove (Yerkes, 1914;
Coburn and Yerkes, 1915; Yerkes and Coburn, 1915). The method has also
been applied with most gratifying results to the study of the
characteristics of ideational behavior in human defectives,--children,
and adults,--and in subjects afflicted with various forms of mental
disease. It is at present being tried out as a practical test in
connection with vocational guidance and various forms of institutional
examination, such as psychopathic hospital and court examinations.

As no adequate description of the method has yet been published to which
I can here refer, it will be necessary to present its salient
characteristics along with a description of the special form of
apparatus which was found suitable for use with monkeys and apes.

The method is so planned as to enable the observer to present to any
type or condition of organism which he wishes to study any one or all of
a series of problems ranging from the extremely simple to the complex
and difficultly soluble. All o