A report from the Supervisory Psychologist
Reprinted from the American Mensa, Ltd. Website
American Mensa is often considered an "expert" source of information on intelligence and IQ testing. Dr. Abbie Salny, Mensa's supervisory psychologist, is the organization's spokesperson on these matters. The following paragraphs are Dr. Salny's answers to some of the most frequently asked questions as excerpted from a recent article published in the Mensa Bulletin, Mensa's monthly member publication.
The French government had commissioned a man named Binet to devise a test that would enable the school authorities to determine which students "could but wouldn't" and which "just couldn't." Thus, the first intelligence test was born. In the 1920s, Lewis Terman tested hundreds of children in the California public schools. He was a professor at Stanford University and had worked on the American version of the Binet test, which became the Stanford-Binet. At the time, tests were established for each age level. The IQ was determined by dividing mental age by chronological age, moving the decimal point two places to the right, and adding one or two zeros as necessary. This was truly a quotient. However, "IQ" is now a misnomer - the score has been read from a standardized table for the past 60 years. A percentile rank, which Mensa uses, is the correct designation.
It has been said that a 140 IQ is a "genius" score, however there is no definition, as such, in either of my psychological dictionaries about "genius." Neither is there an IQ score ranked as "genius." That 140 IQ is actually a misunderstanding. To continue Terman's story, he tested these hundreds of children, picked those with IQs above 140 (on the scale then in use) and proceeded to do a longitudinal study. From this beginning and subsequent publication of the books reporting on the study, the magic figure of IQ 140 came into play and current usage. The IQs of some well-known individuals have been called "genius," such as a book that claimed IQs of 180 and 200 for Alexander Pope and Charles Darwin. However, this is hardly likely, as they died long before the first intelligence test was produced.
For Mensa, an applicant must achieve a score at the 98th percentile on a standardized, supervised intelligence test or equivalent. The 98th percentile is two standard deviations* above the mean (rounded off). The Stanford-Binet and many school tests have a mean of 100 and a standard deviation of 16, so Mensa's qualifying score is 132. On the other hand, the Cattell IIIB and the Raven's Advanced Progressive Matrices (old form) have a mean of 100 and a standard deviation of 24. Mensa requires a score of 148 for these tests. The score of 148 represents exactly the same 98th percentile. An IQ score means nothing without the name of the test by which it was determined. I read of a woman who said that her son had an IQ of 178. Actually, he had taken the old Cattell IIIB, and that 178 IQ is equivalent to 152 IQ on the Stanford-Binet.
*Standard deviation is a mathematically determined figure to account for variances from the average.
Genius may be in the eye of the beholder. Furthermore, a true genius may not score particularly well on a standard group IQ test. We know a Nobel Prize winner who never scored at Mensa level on a school IQ test - he was too busy seeing all the alternate possibilities for each answer. At the present time, all IQ scores are read off of tables. Now there are almost no tests in use that will give extraordinary high IQs except those with very large standard deviations. And really, those who are what we may call a genius don't need a score to prove it.
Abbie F. Salny, Ed.D.
Supervisory Psychologist, American Mensa
Abbie F. Salny, Ed.D., a Mensa member since 1964, is the supervisory psychologist for both American Mensa and Mensa International. She is a retired professor and deputy chairman of the Psychology Department at Montclair (N.J.) State University, a diplomate of the American Board of Professional Psychology, and the author or co-author of several best-selling quiz and puzzle books including the Mensa Genius Quiz Book series. Dr. Salny is also the creator of the 1997, ´98, ´99, and 2000 Mensa Page-A-Day calendars published by Workman. Dr. Salny lives in New Jersey with her husband, Jerry, who is also a member of Mensa.