Carroll’s Three-Stratum Theory of Intelligence
By the late twentieth century, intelligence research had accumulated an awkward abundance of results. Spearman had identified general covariance.
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Cattell-Horn Theory: What Are Fluid and Crystallized Intelligence?
Knowing that intelligence contains broad abilities creates a new question: **what kind of abilities are they, and why do they develop differently?
Thurstone’s Primary Mental Abilities: Is Intelligence Made of Several Abilities?
Once psychologists began taking general intelligence seriously, another problem became harder to ignore.
Spearman’s Two-Factor Theory of Intelligence: What Are g and s?
At the beginning of the twentieth century, psychologists faced an intriguing pattern. Measures that seemed to test quite different mental abilities tended to correlate.
What Is the Positive Manifold — and Why Do Intelligence Tests Correlate?
Give a large group of people a sufficiently varied set of cognitive tests: reasoning, vocabulary, memory, spatial problems, processing speed.
What Does a Standard Score Mean?
A standard score turns raw performance into a common scale so that a result can be interpreted relative to a reference distribution.
What Do IQ Percentiles Mean?
An IQ percentile describes relative standing in a norm group. It is not the percentage of questions answered correctly and not the percentage of intelligence a person possesses.
What Does Average Intelligence Mean?
“Average” is not a kind of person. It is a position within a reference distribution created by comparing performance with an appropriate norm group.
How Stable Is Intelligence Across Life?
People can change substantially while their relative standing compared with others becomes increasingly stable. Those are not contradictory facts.
Intelligence vs Wisdom: What Is the Difference?
Intelligence can help a person reason well. Wisdom asks a different question: how well is judgment used when values, uncertainty, other people and the consequences of action matter?