According to Jim: the flawed normal curve of intelligence.

An old philosopher once opined that "It is not the things we don't know that cause us so much trouble, it is the things we know that ain't so." So it is with the normal curve of intelligence. It is likely that on your bookshelf there are volumes of educational psychology or developmental psychology that contain a neat drawing of the normal curve of intelligence; large in the middle with diminishing numbers at the extremes and, above all, symmetrical in nature. Generations have learned this in school and college. Only one problem, as the philosopher said: "It ain't true."

For one thing, where the average is theoretically 100, the lowest IQ score you can get in a normally developing child is 70 without involving serious neurological or physiological damage to the child. The highest score you can get is over 200 or as high as your test will allow you to score. The curve is clearly tilted to the positive end. Also, there are many more youngsters found at the very top end than would be expected by the normal curve distribution (Robinson, Zigler, & Gallagher, 2000; Silverman, 1998).

We always face a "so what" in such a discussion, but the truth of the matter is that we have drawn some very wrong conclusions based on this spurious normal curve. For example:

1. Intelligence is a biological property and is relatively unchangeable. Some social scientists who have looked at performance across generations (e.g., Flynn, 1999) point out that populations regularly gain in IQ scores across generations in ways not explainable through biology.

2. Racial and ethnic differences. Starting from the assumption that IQ is genetically based, entire books (see The Bell Curve by Herrnstein & Murray, 1994) have been written with their authors maintaining that some ethnic and racial groups are clearly superior to others based on obtained IQ scores. But these scores are clearly influenced by environmental factors, so the argument is flawed.

3. We are limited in the number of gifted individuals we have. In the past, some persons in gifted education have spent a lot of time seeking the 3% of pure gifted students (based on the normal curve statistics) instead of trying to expand the pool of gifted and talented students. Based on what we know in 2008, what are the apparent truths of the matter?

THE IMPORTANCE OF EARLY YEARS

We have come to realize the extreme importance of the early years of birth through 5 to the full development of the individual's potential. Language provides a key vehicle for advanced thinking to ride upon. Failure to stimulate language early or to provide a healthy environment will limit the intellectual potential of children. This realization has fueled the growth of prekindergarten programs.

THERE ARE MANY MORE TALENTED AND GIFTED STUDENTS THAN WE THOUGHT

As we realize this, we also can carry the thought that we can make even more gifted and talented students with judicious stimulation of the educational programs and preschool environments.

Does this mean that everyone can be gifted? Not a chance! The human organism is not that pliable. But if you are in gifted education, the future looks very promising.

SO ARE WE ALL EQUAL--CHINESE, IRISH, IRANIANS, ETC.?

Does our evidence prove that there are no differences between races or ethnic groups in mental abilities? No, it only means that the IQ data are flawed and can't be used for that purpose. We do know that the highest levels of measured mental ability have been attained by members of every racial and ethnic group, so perhaps the search for superiority in mental ability is not so much a scientific search than a misguided political one.

REFERENCES

Flynn, J. (1999). Searching for justice: The discovery of IQ gains over time. American Psychologist, 54(1), 29-51.

Herrnstein, R. J., & Murray, C. (1994). The bell curve: Intelligence and class structure in American life. New York: Free Press.

Robinson, N., Zigler, E., & Gallagher, J. (2000). Two tails of the normal curve: Similarities and differences in the study of mental retardation and differences in the study of mental retardation and giftedness. American Psychologist, 55, 1413-1424.

Silverman, L. (1998). The highly gifted. In J. Van Tassel-Baska (Ed.), Excellence in educating gifted and talented learners (pp. 115-128). Denver, CO: Love Publishing.