I Q as high as 80. Some of the border-line cases, with even less
intelligence, may be so well endowed in other mental traits that they
are capable of becoming dependable unskilled laborers, and of supporting
a family after a fashion.

_Examples of border-line deficiency_

_S. F. Girl, age 17; mental age 11-6; I Q approximately 72
(disregarding age above 16 years)._ Father intelligent; mother
probably high-grade defective. Lives in a good home with aunt,
who is a woman of good sense and skillful in her management of
the girl. S. F. has attended excellent schools for eleven years
and has recently been promoted to the seventh grade. The teacher
admits, however, that she cannot do the work of that grade, but
says, "I haven't the heart to let her fail in the sixth grade
for the third time." She studies very hard and says she wants to
become a teacher! At the time the test was made she was actually
studying her books from two to three hours daily at home. The
aunt, who is very intelligent, had never thought of this girl as
feeble-minded, and had suffered much concern and humiliation
because of her inability to teach her to conduct herself
properly toward men and not to appropriate other people's
property.

[Illustration: FIG. 9. BALL AND FIELD TEST S. F., AGE 17; MENTAL
AGE 11-6]

S. F. is ordinarily docile, but is subject to fits of anger and
obstinacy. She finally determined to leave her home, threatening
to take up with a man unless allowed to work elsewhere. Since
then she has been tried out in several families, but after a
little while in a place she flies into a rage and leaves. She is
a fairly capable houseworker when she tries.

This young woman is feeble-minded and should be classed as such.
She is listed here with the border-line cases simply for the
reason that she belongs to a group whose mental deficiency is
almost never recognized without the aid of a psychological test.
Probably no physician could be found who would diagnose the
case, on the basis of a medical examination alone, as one of
feeble-mindedness.

_F. H. Boy, age 16-6; mental age 11-5; I Q approximately 72
(disregarding age above 16 years)._ Tested for three successive
years without change of more than four points in I Q. Father a
laborer, dull, subject to fits of rage, and beats the boy.
Mothe