Processing Speed: The Ability That Explains the Others
Processing speed peaks before any other cognitive ability. Salthouse's theory of cognitive ageing, inspection time and IQ, and why a low speed score is not a low ability.
6 min read
IQ Insights
In-depth, expert-reviewed guides on IQ scores, intelligence testing, demographics and how to take a test — from the IQCognify editorial team.
Latest articles
Raven's Progressive Matrices: What It Measures & What It Doesn't
Raven's measures eductive ability — half of Spearman's g. Why it is not an IQ test, why it is culture-reduced rather than culture-fair, and where to take the real thing.
6 min read
Stanford–Binet Test: Structure, Scores & the SD-16 Confusion
The SB5's five factors, its adaptive routing, and the standard-deviation change from 16 to 15 that makes old Stanford–Binet scores incomparable with new ones.
6 min read
The Highest IQ Ever Recorded: Why There Is No Answer
Guinness retired the highest-IQ record in 1990. Where the famous 228 came from, why the test's own manual capped at 170, and why no IQ above 200 is measured.
7 min read
Is Intelligence Genetic? What Heritability Really Means
Heritability rises from 20% in infancy to 80% in later adulthood — and means almost nothing people think it means. Why it depends on the society doing the measuring.
7 min read
Do Brain Training Games Work? What the Evidence Shows
11,430 people trained for six weeks and transferred nothing. Near vs far transfer, the n-back replication failure, and why the FTC fined Lumosity $2 million.
6 min read
Does IQ Predict Success? The Numbers Changed in 2022
The canonical .51 validity for cognitive ability was inflated by a flawed correction. The corrected figure is .31 — behind structured interviews and biodata.
6 min read
The WISC-V: How the Children's IQ Test Actually Works
The WISC-V Full Scale IQ comes from seven subtests, not ten — and independent factor analysis of 16 models does not support its five-factor structure.
6 min read
Spatial Reasoning: The Ability Most Tests Ignore
Spatial ability predicts STEM achievement beyond maths and verbal — and no admissions test measures it. The 217-study meta-analysis showing it can be trained.
6 min read