Classification Of Intelligence Quotients

What do the above I Q's imply in such terms as feeble-mindedness, border-line

intelligence, dullness, normality, superior intelligence genius, etc.? When we use

these terms two facts must be borne in mind: (1) That the boundary lines between

such groups are absolutely arbitrary, a matter of definition only; and

(2) that the individuals comprising one of the groups do not make up a

homogeneous type.

theless, since terms like the above are convenient and will

probably continue to be used, it is desirable to give them as much

definiteness as possible. On the basis of the tests we have made,

including many cases of all grades of intelligence, the following

suggestions are offered for the classification of intelligence


_I Q_ _Classification_

Above 140 "Near" genius or genius.

120-140 Very superior intelligence.

110-120 Superior intelligence.

90-110 Normal, or average, intelligence.

80- 90 Dullness, rarely classifiable as feeble-mindedness.

70- 80 Border-line deficiency, sometimes classifiable as

dullness, often as feeble-mindedness.

Below 70 Definite feeble-mindedness.

Of the feeble-minded, those between 50 and 70 I Q include most of the

morons (high, middle, and low), those between 20 or 25 and 50 are

ordinarily to be classed as imbeciles, and those below 20 or 25 as

idiots. According to this classification the adult idiot would range up

to about 3-year intelligence as the limit, the adult imbecile would have

a mental level between 3 and 7 years, and the adult moron would range

from about 7-year to 11-year intelligence.

It should be added, however, that the classification of I Q's for the

various sub-grades of feeble-mindedness is not very secure, for the

reason that the exact curves of mental growth have not been worked out

for such grades. As far as the public schools are concerned this does

not greatly matter, as they never enroll idiots and very rarely even the

high-grade imbecile. School defectives are practically all of the moron

and border-line grades, and these it is important teachers should be

able to recognize. The following discussions and illustrative cases will

perhaps give a fairly definite idea of the significance of various

grades of intelligence.[28]

[28] The clinical descriptions to be given are not complete and are

designed merely to aid the examiner in understanding the significance of

intelligence quotients found.