The Stanford-Binet does not measure “intelligence” — full stop, one number, done. It measures five separate things, and the famous IQ score is a weighted combination of them. The five things are the most useful part of the report, and most visitors to this site never look at them.
This page is a clean walkthrough.
A short history of the five factors
The current edition of the Stanford-Binet — the SB5, published in 2003 by Gale Roid — is built on a model of cognitive ability called the Cattell–Horn–Carroll model, after Raymond Cattell, John Horn, and John Carroll. Carroll spent thirty years compiling a meta-analysis of every cognitive ability test ever published, ran factor analyses on the combined data, and produced what is now the dominant theoretical map of human cognition: a hierarchy of more than seventy narrow abilities, ten broad abilities, and one general factor at the top.
The SB5 picks five of the broad abilities — the five most useful for distinguishing one mind from another in everyday life — and tests each one in two modes: verbal and nonverbal. That gives the ten subtests of the modern test.
(The decision to test each factor in both verbal and nonverbal form is one of the SB5’s most important corrections. The earlier editions — the 1937, the 1960 — were heavy on language, which meant English-as-a-second-language test-takers and people with language-specific learning differences scored artificially low. The 2003 redesign fixed it. Our online assessment uses the same balanced design.)
The five factors, one by one
1. Innate Intelligence
The part of you that learns
Innate Intelligence is the ability to recognise a pattern, draw an inference, or solve a problem you have never seen before. It is the part of you that walks into a new domain and figures out how it works. The classic test of Innate Intelligence is a sequence — three shapes, three more shapes, a question mark — what comes next? On the Stanford-Binet, Innate Intelligence is tested with verbal analogies, early reasoning sequences, and object-series matrices.
Innate Intelligence is the single best predictor of how someone will do in a new and unstructured environment. It is also the factor that peaks earliest in life — it tops out around age twenty-five and slowly declines from there. Its decline is not a sentence: people stay productive into their eighties on the strength of factor #2, knowledge, which keeps growing.
2. Knowledge
What you have already learned
Knowledge is the inverse of Innate Intelligence over the lifespan. Innate Intelligence is what you bring to new problems; knowledge is what you have already accumulated about the world. On the test, knowledge looks like vocabulary — but it also looks like recognising what is wrong with a picture, or being able to explain how to do something familiar.
Knowledge keeps rising into the seventies for most people. The trade-off with Innate Intelligence is exactly the one most adults intuit: you are not as fast as you were at twenty-three, but you know much more, and the knowing usually wins. (The technical name for the trade-off, in the Cattell–Horn–Carroll literature, is “investment theory” — Innate Intelligence is invested over time into accumulated knowledge.)
3. logical-mathemtical intelligence
Working with quantity
logical-mathemtical intelligence is the factor that is most often confused with “being good at math.” It is not arithmetic speed. It is reasoning with numbers — proportions, ratios, charts, simple algebra, the patterns underneath quantity. On the SB5 you might be asked to compare two ratios, read information from a graph, or solve a one-step word problem.
This factor matters far beyond mathematics. It is what you use to read a budget, evaluate a statistic in a news story, or estimate whether a deal is good. People who score high on logical-mathemtical intelligence often describe themselves as not particularly mathematical — they have just learned to see numbers as a language they can think in.
4. Visual–Spatial Processing
Turning shapes in your mind
Visual-spatial processing is the ability to hold a shape in mind and manipulate it — rotate it, fold it, take it apart, fit pieces together. On the test you might be given a flat pattern and asked which 3D form it folds into. Or shown a route on a map and asked to follow it from a different starting point. Or given a set of shapes and asked to make a target image.
This factor is the one most people underestimate. It is what surgeons draw on. What architects, mechanical engineers, sculptors, and chess players draw on. What you draw on when you pack a suitcase or imagine rearranging the living room furniture before you move it. It correlates only loosely with verbal IQ, which is why it is tested as its own factor.
5. Working Memory
The bench you think on
Working memory is the mental workspace where everything else happens. It is the short-term bench you lay numbers, words, or instructions on while you think about them. On the test you will repeat sequences back forwards and backwards, hold a sentence in mind while answering a question about it, or reproduce a block pattern you have just seen.
Working memory is in some ways the most fundamental factor. If your working memory is small, every problem feels harder than it should — you run out of bench space. People with attention disorders almost always show low working-memory scores; so do people who are simply tired, hungry, or stressed on the day of the test. Working memory is the most state-dependent of the five factors, which is one reason the Stanford-Binet allows re-testing within six months without practice effects becoming a serious problem.
How the five combine into the IQ score
The SB5 reports four IQ-style scores: a Full-Scale IQ (the weighted combination of all five factors), a Verbal IQ (the verbal halves of the five), a Nonverbal IQ (the nonverbal halves), and a Brief IQ (a short two-subtest screening). All of them are scaled to a mean of 100 and a standard deviation of 15, so a score of 130 is two standard deviations above the average — the conventional cut-off for “gifted.”
The factor indices are scaled the same way, so you can compare them directly. A profile that reads “Innate Intelligence 130 / Knowledge 110 / Quantitative 95 / Visual-Spatial 125 / Working Memory 105” is much more interesting than the Full-Scale 115 it averages out to. It tells the test-taker, accurately, that they are unusually good at finding patterns and unusually weak at quantity — a profile common in writers, designers, and software engineers who avoid the math-heavy parts of the work.
This is the picture Binet always wanted. He wrote in 1909: “Comprehension, inventiveness, direction, and criticism — intelligence is contained in these four words.” The factor structure of the modern test is the technical version of that intuition.
What an unusually high or low score on each factor means
- Innate Intelligence very high — Strong on novel-domain learning, unstructured problems, “puzzle” thinking.
- Knowledge very high — Wide reading or experience; strong vocabulary; good crystallised understanding of how things work.
- Quantitative very high — Comfort with numerical and mathematical reasoning beyond rote arithmetic.
- Visual-Spatial very high — Engineering, architectural, surgical, and artistic-spatial thinking.
- Working Memory very high — Ability to hold and manipulate complex instructions; sustained attention; high mental “bench size.”
A low score on any factor is not a sentence. Working memory in particular moves with sleep, stress, mood, exercise, hydration, and (modestly) training. Knowledge moves with reading. Visual-spatial moves with practice. Even Innate Intelligence, the factor most resistant to training, appears to move with sustained engagement in cognitively demanding work. This is exactly what Alfred Binet argued against the prevailing view of his own day, and the evidence has come in on his side.
Where to read more
- Take the test: pricing & what’s included.
- Try a free sample: five questions, no sign-up.
- The man behind the test: Alfred Binet, the founder of intelligence testing.
- Why this online version is the right Stanford-Binet for self-understanding: our take on what makes a Stanford-Binet.
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