ON MENTAL AND PHYSICAL FACTORS INVOLVED IN EDUCATION. 529% 
have been developed for the purpose in question, and that a vast mass. 
of data has been collected in various countries. On the whole, 
although many amendments in detail have been suggested, competent 
judges seem unanimous in reporting the tests to be of great value. 
A comprehensive summary of them will be found in Whipple’s 
“Manual of Mental and Physical Tests,’ and they have.been referred 
to in Appendix III. to the last report of this Committee. 
At present the most systematic series of tests appears to be that of 
Binet, whose latest developments are given in the ‘ Bulletin de la 
société libre pour ]’étude de l’enfant,’ April 1911. Among the mosi 
striking instances of their application is that of Goddard. But the tests 
appear to be still far from finality, and it would be unwise to use 
them without regard to the fact that many investigators are gradually 
evolving the general principles which should govern their usage. 
The first of these principles concerns the reliability of the tests. It 
has been shown that, in order to obtain consistent results, a test 
must be of a certain thoroughness, the minimum time required varying 
largely according to the particular test. This aspect has been greatly 
neglected in the past, and some of the tests now currently recom- 
mended appear to be so unreliable as to be of little real use. Research 
is beginning to determine the reliability of different tests, so that much 
more information on the subject will soon be available. 
Another principle generally admitted by competent investigators 
is the absolute need of diversity. The person who is not versed in 
psychological method is inclined to pronounce a confident opinion about a 
child on the strength of one single manifestation—-as he believes—of 
conspicuous intelligence. Experiment has shown, on the contrary, 
that the performances of any person, normal or abnormal, are very 
unequal; unquestionably defective children haye proved themselves 
occasionally capable of performances astonishing even to those in regular 
charge of them. These two principles of reliability and diversity are 
in direct opposition, for instance, to the formation of a definite verdict 
as to the child's normality on the sole basis of two or three summary 
fests (such as asking him ‘ What is a cat?’ or making him count his 
fingers). 
The third principle concerns the relative value of the different tests. 
It is generally agreed that this varies greatly in the case of normal 
persons, some tests giving much better information than others; 
operations of a ‘ higher’ kind (such as reasoning, &c.) incline to give 
more valuable results than sensory or motor tests. But in the case 
of defective children it has been reported that many of the lower 
(and particularly the motor) tests give information as good as any 
others, and are more convenient. Here again further investigation is 
wanted. 
The next principle refers to the significance of the results of the 
tests. Opinions are less unanimous, but at least one point may be 
regarded as definitely settled. It has been found that failure to 
succeed in any particular performance by no means proved incapacity 
for all performances of the same general form; for instance, failure 
* See Pedagogical Seminary, June 1911; also the T'raining School, 1910, vol. 
vi,, No. 11. 
