Question
Is IQ based on knowledge?
Short answer
Partly. Most full IQ tests combine knowledge-based tasks, such as vocabulary, with reasoning tasks that need no prior knowledge, such as matrix puzzles. Psychologists call these crystallized and fluid intelligence. The KBIT-2, for example, reports a Crystallized (Verbal) score and a Fluid (Nonverbal) score alongside one IQ composite.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
Two kinds of ability on one test
Raymond Cattell distinguished fluid intelligence, reasoning with new material, from crystallized intelligence, the knowledge you have built up (Wikipedia: Fluid and crystallized intelligence). Clinical tests measure both. The WAIS-5's Verbal Comprehension index uses subtests such as Vocabulary and Similarities, while its Fluid Reasoning index uses Matrix Reasoning and Figure Weights (Pearson: WAIS-5 overview). The KBIT-2 makes the split explicit with Crystallized (Verbal) and Fluid (Nonverbal) scores (Pearson: KBIT-2).
Tests that lean away from knowledge
Some tests try to minimize knowledge. The Cattell Culture Fair Intelligence Test was designed to measure intelligence with minimal influence from verbal fluency and educational level (Buros: CFIT (store)). Matrix tests work the same way. They are useful when language or schooling would otherwise distort a score, though no test removes background entirely. See culture-fair IQ tests.
Try one · Logical Reasoning
Which tile completes the second pair?
Tap the option you think is right, or show the answer.
Show the answer
The missing panel shows a large hatched triangle pointing up, with small solid shapes: a diamond at the bottom-left corner (option 3).
How to solve it
- Compare the first two panels and name exactly what changed.
- The main shape and the small shapes swap forms: the main shape takes the form of the small ones, and the small ones take the form of the main shape.
- Nothing else changes.
- Apply the same change to the third panel: a large hatched diamond, with small solid shapes: a triangle at the bottom-left corner.
- So the missing panel shows a large hatched triangle pointing up, with small solid shapes: a diamond at the bottom-left corner.
That was 1 puzzle. The full test has 25.
Knowledge and reasoning feed each other
The line between them is not a wall. A 2018 meta-analysis found that each additional year of education raises cognitive abilities by about 1 to 5 IQ points, across all broad ability categories studied, including reasoning (Ritchie & Tucker-Drob, 2018). And the two follow different paths with age: vocabulary and knowledge keep rising into the sixties, while speed and some reasoning measures peak in the late teens and twenties (Hartshorne & Germine, 2015).
What the IQ Octopus test measures
Our test is reasoning-only: visual and number puzzles with no vocabulary or general knowledge items. That makes it a fluid reasoning estimate rather than a full profile. For more, read fluid vs crystallized intelligence, verbal vs nonverbal intelligence and how the test works.
Sources
- Fluid and crystallized intelligence. Wikipedia. en.wikipedia.org/wiki/Fluid_and_crystallized_intelligence
- Pearson. Kaufman Brief Intelligence Test, Second Edition (KBIT-2), product page. www.pearsonassessments.com/store/en/usd/p/100000390.html
- Pearson. WAIS-5 overview brochure (C12396). 2025. www.pearsonassessments.com/content/dam/school/global/clinical/us/assets/wais-5/wais-5-overview-brochure.pdf
- Buros Center for Testing. Culture Fair Intelligence Test, marketplace listing. marketplace.unl.edu/buros/culture-fair-intelligence-test.html
- Ritchie, S. J., & Tucker-Drob, E. M. (2018). How much does education improve intelligence? A meta-analysis. Psychological Science, 29(8), 1358-1369. doi.org/10.1177/0956797618774253
- Hartshorne, J. K., & Germine, L. T. (2015). Psychological Science, 26(4), 433-443. doi.org/10.1177/0956797614567339