This is a list of I.Q. ranges with for each a brief description of typical functioning and other features. The I.Q.s are expressed on a scale with a general population mean of 100 and standard deviation of 15. They refer to scores on adult tests only, by adult norms. The exact cut-offs for the ranges are arbitrary, and one should realize that functioning depends on more than I.Q. alone, particularly, for instance, on conscientiousness and associative horizon.
In addition it is known that I.Q. has the greatest significance to real-life functioning (and the highest correlation with "g", the general factor shared by all intelligence tests) at the lowest ranges, and becomes less important as you go higher; The more you have of it, the less important it gets, just as with money. It is unknown if I.Q.s beyond about 140 have any extra significance.
Usually multi-handicapped with obvious physical deformities and short life expectancy. Heavily dependent on others. Can learn no or only the very simplest tasks.
Basic intellectual tasks, including language, are difficult to learn. Can learn some self-care behaviour but remain dependent on others. There are usually motor problems and physical anomalies. Usually not employable.
Profound and severe retardation are typically caused by brain damage during pregnancy or early in life, and as such not genetic and not inherited.
Can learn simple life skills and employment tasks with special education. May be employed in special settings, and achieve some independence. Often socially immature. The most intelligent animals, such as some chimpanzees, parrots, and dolphins, are in this range. Chimpanzee I.Q. scores are sometimes even quoted as high as 80 or 90, but those are childhood age-peer scores that correspond to adult I.Q.s of only just over 40.
Educable, can learn to care for self, employable in routinized jobs but require supervision, might live alone but do best in supervised settings, immature but adequate social adjustment, usually no obvious physical anomalies.
Moderate and mild retardation, contrary to the more severe forms, are typically not caused by brain damage but part of the normal variance of intelligence, and therefore largely genetic and inherited. This is important with regard to the question whether or not retarded persons should have children; For especially the moderate and mild forms of retardation, wherewith it physically is possible to have children, are the most likely to be inherited.
Limited trainability. Have difficulty with everyday demands like using a phone book, reading bus or train schedules, banking, filling out forms, using appliances like a video recorder, microwave oven or computer, etcetera, and therefore require assistance from relatives or social agencies in the management of their affairs. Can be employed in simple tasks but require supervision.
Above the threshold for normal independent functioning. Can perform explicit routinized hands-on tasks without supervision as long as there are no moments of choice and it is always clear what has to be done. Assembler, food service.
This is also the I.Q. range most associated with violence. Most violent crime is committed by males from this range. This does obviously not imply that all males in this range are violent. But when the modal I.Q. of a group is in this range, one may expect trouble with with relatively many male members of that group. When the modal I.Q. of a society is raised upward of this range, violence decreases as fewer males fall in this range then. When the modal I.Q. of a society is below this range to begin with though, raising it will INCREASE violence.
And, this is the range into which men of average or just above average intelligence sink when under the influence of alcohol; Alcohol reduces I.Q. by 10 to 25 points while drunk (own observation), which explains why many drunk men are violent and aggressive (own hypothesis).
Able to learn a trade in a hands-on manner and perform tasks involving decisions. Craftsman, sales, police officer, clerk.
Able to learn from written materials. Employable in senior positions.
Able to learn in "college" format. Bachelor degrees. Manager, teacher, accountant. Just capable of taking high-range tests.
Capable of gathering and inferring own information. Master degrees. Attorney, chemist, executive. About 93 % of high-range candidates score I.Q. 120 or higher.
May be able to write a legible piece of text like an article or modest novel. Minor literary figures. Ph.D. in the "soft" sciences. In this range lies the mode of scores on high-range tests, and almost 80 % of high-range candidates score I.Q. 130 or higher. Regular psychology's I.Q. tests should not be trusted beyond this range as their correlation with "g" breaks down there, if such scores are given at all.
Capable of rational communication and scientific work. From this range on, only specific high-range tests should be considered. Important scientific discoveries and advancement are possible from the upper part of this range on.
We do not yet know if intelligence from about this range on is simply the extreme end of a normal distribution centered at 100 and largely formed by heredity, or if high intelligence may in some cases have other causes (non-inherited or non-genetic) which cause it to deviate from the normal curve centered at 100 and form a kind of "bump" in the far right tail, similar to the bump in the retarded range (which is caused by non-inherited and non-genetic effects).
About one in two high-range test candidates score I.Q. 140 or higher.
About one in four high-range test candidates score I.Q. 150 or higher. Otherwise under investigation.
About one in ten high-range test candidates score I.Q. 160 or higher. Otherwise under investigation.
About one in a hundred high-range test candidates score I.Q. 170 or higher. Otherwise under investigation; A report on this specific group is Statistics of the top scorers.
In this range one would expect the I.Q.s of the few most intelligent individuals alive. About one in a thousand high-range test candidates score I.Q. 180 or higher.
[I.Q. ranges in relation to stages of human evolution]
[I.Q. ranges in relation to stages of civilization]
[To High-Range Intelligence Tests]