The Intelligence Of Retarded Children Usually Overestimated

One of the most common errors made by the teacher is to overestimate the

intelligence of the over-age pupil. This is because she fails to take

account of age differences and estimates intelligence on the basis of

the child's school performance in the grade where he happens to be

located. She tends to overlook the fact that quality of school work is

no index of intelligence unless age is taken into account. The question

should be, not, "Is this child doing his school work well?" but rather,

"In what school grade should a child of this age be able to do

satisfactory work?" A high-grade imbecile may do average work in the

first grade, and a high-grade moron average work in the third or fourth

grade, provided only they are sufficiently over-age for the grade in


Our experience in testing children for segregation in special classes

has time and again brought this fallacy of teachers to our attention. We

have often found one or more feeble-minded children in a class after

the teacher had confidently asserted that there was not a single

exceptionally dull child present. In every case where there has been

opportunity to follow the later school progress of such a child the

validity of the intelligence test has been fully confirmed.

The following are typical examples of the neglect of teachers to take

the age factor into account when estimating the intelligence of the

over-age child:--

_A. R. Girl, age 11; in low second grade._ She was able to do

the work of this grade, not well, but passably. The teacher's

judgment as to this child's intelligence was "dull but not

defective." What the teacher overlooked was the fact that she

had judged the child by a 7-year standard, and that, instead of

only being able to do the work of the second grade

indifferently, a child of this age should have been equal to the

work of the fifth grade. In reality, A. R. is definitely

feeble-minded. Although she is from a home of average culture,

is 11 years old, and has attended school five years, she has

barely the intelligence of the average child of six years.

_D. C. Boy, age 17; in fifth grade._ His teacher knew that he

was dull, but had not thought of him as belonging to the class

of feeble-minded. She had judged this boy by the 11-year

standard and had perhaps been further misled by his normal

appearance and exceptionally satisfactory behavior. The Binet

test quickly showed that he had a mental level of approximately

9 years. There is little probability that his comprehension will

ever surpass that of the average 10-year-old.

_R. A. Boy, age 17; mental age 11; sixth grade; school work

"nearly average"; teacher's estimate of intelligence "average."_

Test plainly shows this child to be a high-grade moron, or

border-liner at best. Had attended school regularly 11 years and

had made 6 grades. Teacher had compared child with his

12-year-old classmates.

_H. A. Boy, age 14; mental age 9-6; low fourth grade; school

work "inferior"; teacher's estimate of intelligence "average."_

The teacher blamed the inferior quality of school work to "bad

home environment." As a matter of fact, the boy's father is

feeble-minded and the normality of the mother is questionable.

An older brother is in a reform school. We are perfectly safe in

predicting that this boy will not complete the eighth grade even

if he attends school till he is 21 years of age.

_F. I. Boy, age 12-11; mental age 9-4; third grade; school work

"average"; teacher's estimate of intelligence "average"; social

environment "average"; health good and attendance regular._

Intelligence and school success are what we should expect of an

average 9-year-old.

_D. A. Boy, age 12; mental age 9-2; third grade; school work

"inferior"; teacher's estimate of intelligence "average."_

Teacher imputes inferior school work to "absence from school and

lack of interest in books"; we have yet to find a child with a

mental age 25 per cent below chronological age who _was_

particularly interested in books or enthusiastic about school.

_C. U. Girl, age 10; mental age 7-8; second grade; school work

"average"; teacher's estimate of intelligence "average."_

Teacher blames adenoids and bad teeth for retardation. No doubt

of child's mental deficiency.

_P. I. Girl, age 8-10; mental age 6-7; has been in first grade

21/2 years; school work "average"; teacher's estimate of

intelligence "average."_ The mother and one brother of this girl

are both feeble-minded.

_H. O. Girl, age 7-10; mental age 5-2; first grade for 2 years;

school work "inferior"; teacher's estimate of intelligence

"average."_ The teacher nevertheless adds, "This child is not

normal, but her ability to respond to drill shows that she has

intelligence." It is of course true that even feeble-minded

children of 5-year intelligence are able to profit a little from

drill. Their weakness comes to light in their inability to

perform higher types of mental activity.


already mentioned the frequent failure of teachers and parents to

recognize superior ability. The fallacy here is again largely due to

the neglect of the age factor, but the resulting error is in the

opposite direction from that set forth above. The superior child is

likely to be a year or two younger than the average child of his grade,

and is accordingly judged by a standard which is too high. The following

are illustrations:--

_M. L. Girl, age 11-2; mental age "average adult" (16); sixth

grade; school work "superior"; teacher's estimate of

intelligence "average."_ Teacher credits superior school work to

"unusual home advantages." Father a college professor. The

teacher considers the child accelerated in school. In reality

she ought to be in the second year of high school instead of in

the sixth grade.

_H. A. Boy, age 11; mental age 14; sixth grade; school work

"average"; teacher's estimate of intelligence "average."_

According to the supplementary information the boy is

"wonderfully attentive," "studious," and possessed of

"all-round ability." The estimate of "average intelligence" was

probably the result of comparing him with classmates who

averaged about a year older.

_K. R. Girl, age 6-1; mental age 8-5; second grade; school work

"average"; teacher's estimate of intelligence "superior"; social

environment "average."_ Is it not evident that a child from

ordinary social environment, who does work of average quality in

the second grade when barely 6 years of age, should be judged

"very superior" rather than merely "superior" in intelligence?

The intelligence quotient of this girl is 140, which is not

reached by more than one child in two hundred.

_S. A. Boy, age 8-10; mental age 10-9; fourth grade; school work

"average"; teacher's estimate of intelligence "average."_

Teacher attributed school acceleration to "studiousness" and

"delight in school work." It would be more reasonable to infer

that these traits are indications of unusually superior