similarly tested, and comparatively negligible
differences have been found. In regard to the five senses,
their efficiency seems to be about equal in all the races of
mankind. The proverbial keenness of vision of the Indian, for
example, is found to be due to a superior training in its use, a
training made imperative by the conditions of Indian life. In
reaction time tests--that is, tests in the speed of simple mental
and motor performances--the time consumed in response
has been found to be about the same for all races tested. The
results have been similar with regard to certain simple processes
of judgment or inference:

There are a number of illusions and constant errors of judgment
which are well known in the psychological laboratory, and which
seem to depend, not on peculiarities of the sense organs, but on
quirks and twists in the process of judgment. A few of these have
been made the matter of comparative tests, with the result that
peoples of widely different cultures are subject to the same errors,
and in about the same degree. There is an illusion which occurs
when an object, which looks heavier than it is, is lifted by the hand;
it then feels, not only lighter than it looks, but even lighter than it
really is. The contrast between the look and the feel of the thing
plays havoc with the judgment. Women are, on the average, more
subject to this illusion than men. The amount of this illusion has
been measured in several peoples, and found to be, with one or two
exceptions, about the same in all. Certain visual illusions, in which
the apparent length or direction of a line is greatly altered by the
neighborhood of other lines, have similarly been found present in all
races tested, and to about the same degree. As far as they go, these
results tend to show that simple sorts of judgment, being subject
to the same disturbances, proceed in the same manner among various
peoples; so that the similarity of the races in mental processes
extends at least one step beyond sensation.[1]

[Footnote 1: Woodworth: "Racial Differences in Mental Traits,"
_Science_, New Series, vol. 31, pp. 179-81.]

Professor Woodworth also points out that these simple
tests are not adequate to measure general intelligence.

A good test for intelligence would be much appreciated by the
comparative psychologist, since, in spite of equal standing in such
rudimentary matters as the senses and bodily movement, attention
and the simpler sorts of