Question
Can your IQ change?
Short answer
Yes, a measured IQ can change. Retaking a test raises scores by about 4 points on average, every score carries a few points of measurement error, and average scores rose across the 20th century. Because IQ is scored against your own age group, getting older does not by itself lower it.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
Three things that move a measured score
Practice
A meta-analysis of retest studies found that taking a cognitive ability test again raises scores by about a quarter of a standard deviation on average, roughly 4 IQ points, and more when the same form is reused (Hausknecht et al., 2007). That gain mostly reflects knowing the format, not a change in underlying ability. See does retaking an IQ test raise your score.
Measurement error
No test measures perfectly. Clinical manuals report a confidence interval, often around plus or minus 5 points at 95%, rather than one exact value (Wechsler, 2008). Two careful tests a month apart can easily differ by a few points with nothing real having changed.
Generations
Average measured IQ rose through the 20th century. A 2015 meta-analysis of 271 samples estimated about 2.8 points per decade and found the gains slowing in recent decades (Pietschnig & Voracek, 2015). This is why tests are periodically renormed. It describes populations, not one person's change. The Flynn effect guide has the details.
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 solid triangle pointing up, with small solid shapes: a circle at the right side and a circle at the left side (option 5).
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 solid circle, with small solid shapes: a triangle at the right side and a triangle at the left side.
- So the missing panel shows a large solid triangle pointing up, with small solid shapes: a circle at the right side and a circle at the left side.
That was 1 puzzle. The full test has 25.
What age does and does not do
Modern tests compare you with people your own age (Wikipedia: Intelligence quotient). A 70-year-old who answers fewer speed items than they did at 30 can still score the same IQ, because their comparison group changed too. Some raw abilities, like processing speed, peak early, while vocabulary keeps rising for decades. Read does IQ decline with age for more.
What this means for your own score
Treat any single score as a range, not a fixed point. If you retest, expect some movement and do not read a few points either way as a real change. If you are curious about genes, heritability of intelligence rises from about 20% in infancy to perhaps 80% in later adulthood (Plomin & Deary, 2015), but that is a statistic about groups. The page on whether IQ is genetic explains what that number can and cannot say.
Sources
- Hausknecht, J. P., Halpert, J. A., Di Paolo, N. T., & Moriarty Gerrard, M. O. (2007). Journal of Applied Psychology, 92(2), 373-385. doi.org/10.1037/0021-9010.92.2.373
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.
- Pietschnig, J., & Voracek, M. (2015). One century of global IQ gains. Perspectives on Psychological Science, 10(3), 282-306. doi.org/10.1177/1745691615577701
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient
- Plomin, R., & Deary, I. J. (2015). Molecular Psychiatry, 20, 98-108. doi.org/10.1038/mp.2014.105