French psychologist Alfred Binet developed the intelligent quotient method in 1904. The French government commissioned him to discover a procedure for making distinctions between students who were of "normal" intelligence and students who were mentally inferior. The idea was to place the less-intelligent students in separate schools where they could receive special attention. Using Binet's IQ method, a child at the normal level of intelligence for her age would have an IQ of 100.
Most of the attributes measured by Binet's intelligent quotient level out at around the age of 16, which means his method cannot work for adults. Instead, modern tests utilize a deviation intelligence quotient: They compare test takers to others within their age group rather than all age groups.
Most IQ tests are a series of subtests that measure particular mental attributes such as memory, reasoning and factual knowledge. Cumulatively, these determine a person's score. Each subtest focuses on specific intellectual attributes, including comprehension, digit span (being able to repeat strings of numbers), similarities (determining the likenesses between objects), vocabulary and arithmetic. IQ tests also contain performance activities, which include block design, object assembly, symbols and coding, picture completion and matrix reasoning.
IQ scores of around 55 or below are considered to be indications of some form of mental retardation. Scores of 70 to below 100 could be considered borderline to low average. A score of 115 is labeled high average, while scores of 130 or above are considered genius-level.
It is often argued that intelligence can only be measured relative to a specific culture, and intelligence tests can never be universal or free of this cultural bond. While IQ tests may perform well in predicting success in academia, they do little to measure creativity or interpersonal skills. In addition to causing problems for students with learning disabilities (who may score low because of a deficiency in motor skills or language), IQ tests have proven to be unreliable by a number of researchers. Scores can vary as much as 15 points from one time a person takes the test to another.
Free IQ tests are offered online at http://www.quickiqtest.net/, http://www.intelligencetest.com/ and http://www.aceviper.net/.