Guiding Principles In Choice And Arrangement Of Tests

In choosing his tests Binet was guided by the conception of intelligence which we have

set forth above. Tests were devised which would presumably bring

into play the various mental processes thought to be concerned in

intelligence, and then these tests were tried out on normal children of

different ages. If the percentage of passes for a given test increased

but little or not at all in going from younger to older children this

test was discarded. On the other hand, if the proportion of passes

increased rapidly with age, and if children of a given age, who on other

grounds were known to be bright, passed more frequently than children of

the same age who were known to be dull, then the test was judged a

satisfactory test of intelligence. As we have shown elsewhere,[13]

practically all of Binet's tests fulfill these requirements reasonably

well, a fact which bears eloquent testimony to the keen psychological

insight of their author.

In arranging the tests into a system Binet's guiding principle was to

find an arrangement of the tests which would cause an average child of

any given age to test "at age"; that is, the average 5-year-old must

show a mental age of 5 years, the average 8-year-old a mental age of

8 years, etc. In order to secure this result Binet found that his data

seemed to require the location of an individual test in that year where

it was passed by about two thirds to three fourths of unselected


It was in the assembling of the tests that the most serious faults of

the scale had their origin. Further investigation has shown that a great

many of the tests were misplaced as much as one year, and several of

them two years. On the whole, the scale as Binet left it was decidedly

too easy in the lower ranges, and too difficult in the upper. As a

result, the average child of 5 years was caused to test at not far from

6 years, the average child of 12 years not far from 11. In the Stanford

revision an effort has been made to correct this fault, along with

certain other generally recognized imperfections.