Despite their widespread use, there is a large body of evidence which suggest that IQ tests are not a valid measure of intelligence, because abstract reasoning is only one facet of the full range of mental abilities. …

IQ tests measure a variety of skills like working memory, fluid reasoning, verbal comprehension and more. But he notes the science suggests IQ tests are still not well equipped to provide meaningful scores for these separate abilities, and should be interpreted only as measuring someone’s overall general intelligence.

The most commonly used tests of intelligence are the Wechsler Adult Intelligence Scale, 4th Edition, (WAIS-IV) for adults and the Wechsler Intelligence Scale for Children, 4th Edition, (WISC-IV) for children.

For the highest IQ participants, the drop in performance with age was precipitous– from about 75% correct to about 65% to close to 50% (floor), for college age, 60-74 year old, and 75-90 year old participants, respectively. For the lowest IQ participants, performance was near floor for all three age groups.

Raven’s Advanced Progressive Matrices (RAPM) were used to measure fluid intelligence, Digit Span Sequencing (DSS) was used to measure working memory, Trail Making Test (TMT) was used to measure cognitive flexibility, Design Fluency Test (DFT) was used to measure creativity, and Tower Test (TT) was used to measure …

General intelligence, also known as g factor, refers to the existence of a broad mental capacity that influences performance on cognitive ability measures.

Most studies of the relation between intelligence and mathematics achievement have used a composite measure (e.g., standardized IQ test) that technically does not provide a direct assessment of fluid intelligence but will be highly correlated with it (Walberg, 1984).

But the MIT study showed that educational practices designed to raise knowledge and boost test scores do not improve ‘fluid intelligence,’ which is the ability to think logically and analyse abstract problems – clearly a rather important skill for learners to develop.

Fluid intelligence is trainable to a significant and meaningful degree. Jaeggi et al.’s article (10) is important to the field of intelligence because it shows that training can improve fluid intelligence, can do so across intelligence levels, and can do so in a theory-based way.

These findings suggest that the age-related decline in fluid intelligence is due to general slowing and frontal decline, as well as other unidentified factors.

IQ was originally computed by taking the ratio of mental age to chronological (physical) age and multiplying by 100. Thus, if a 10-year-old child had a mental age of 12 (that is, performed on the test at the level of an average 12-year-old), the child was assigned an IQ of 12/10 × 100, or 120.

Price, a professor at the Wellcome Trust Centre for Neuroimaging at University College London, and colleagues, tested 33 “healthy and neurologically normal” adolescents aged 12 to 16. Their IQ scores ranged from 77 to 135, with an average score of 112.

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Most people (about 68 percent) have an IQ between 85 and 115. Only a small fraction of people have a very low IQ (below 70) or a very high IQ (above 130). The average IQ in the United States is 98.

An IQ score over 140 indicates that you’re a genius or nearly a genius, while 120 – 140 is classed as “very superior intelligence”. 110 – 119 is “superior intelligence”, while 90 – 109 is “normal or average intelligence”.