204	^THE  FACTORS  OF THE MIND
laboratory type, or on assessments of character-qualities and
traits of personality. Whipple's well-known manual, for
example, presents all the more familiar mental tests classified
according to the functions which they were presumably
intended to measure—sensory discrimination, motor capa-
city, attention, memory, and the like. And the various
questionnaires issued year after year for recording children's
behaviour nearly always presuppose some tacit or explicit
classification of the actions to be observed—some hypo-
thetical scheme of ^c propensities,^3 ^£ attitudes/ or ^c unitary
traits.' Evidently, if such classifications are to have any
genuine value, they themselves require first to be sub-
stantiated. And in either case this can only be achieved by
a comprehensive factorial analysis.
Factors specify Relations.—The view to which we have
been led becomes almost unavoidable, when we reflect on
the very different constructions that may be put on the
results of correlating persons : here, as we have seen,
investigators find it much more difficult to agree over what
precisely they have been analysing. Correlations between
traits or tests are almost universally assumed to yield an
analysis of the mind into its component ^c abilities ' : cor-
relations between persons, on the other hand, may be inter-
preted in two seemingly inconsistent ways.
Consider once again the type of inquiry I have been
describing—for example, one of the many experiments in
which a number of persons are asked to rank a series of
English compositions in order of merit, and the rankings are
correlated by persons. What do the results reveal ? Do
they indicate the literary appreciation of the judges, or the
literary merits of the compositions judged ? If the com-
positions are children's essays, and the judges school
examiners, then we shall probably regard the figures as
grading or classifying the compositions judged. If, however,
the judges are children and the compositions extracts from
authors differing widely in literary skill, then we may use
the figures to grade or classify the judges according to their
powers of appreciation. The truth is that with both
experiments what our measurements really express are in
the first instance neither the qualities of the judges by