Question
Does IQ decline with age?
Short answer
Not by itself. IQ is scored against people your own age, so the normal slowing that comes with age does not lower the score. Underneath, abilities do shift: processing speed peaks in the late teens and twenties, while vocabulary and knowledge keep rising into the sixties.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
Why the score holds steady
Modern IQ tests report a deviation IQ: your result is standardized against a sample of people your own age, with a mean of 100 and a standard deviation of 15 (Wikipedia: Intelligence quotient). If everyone in your age group answers a little more slowly than they did twenty years ago, the comparison moves with them. That is why a typical decline in raw speed does not, on its own, lower anyone's IQ score.
This is the whole point of age norms. Without them, a test would mostly measure how old you are.
Try one · Abstract Reasoning
Which tile completes the grid?
Tap the option you think is right, or show the answer.
Show the answer
The missing tile has a large outlined square (option 3).
How to solve it
- Start with the first column and name what changes from tile to tile.
- Every row and every column contains each shape (triangle, square and cross) exactly once.
- Every row and every column contains each fill (outline, solid and hatched) exactly once.
- The size (large) stays the same in every tile.
- Check the rules on the second column, then apply them to the third.
- So the missing tile has a large outlined square.
That was 1 puzzle. The full test has 25.
What does change underneath
Different abilities peak at different ages. In a large study, Hartshorne and Germine found that processing speed and some reasoning measures peak in the late teens and twenties, while vocabulary and accumulated knowledge keep rising into the sixties (Hartshorne & Germine, 2015). Salthouse reported a similar split (Salthouse, 2009).
So a 60-year-old may be slower on a timed puzzle and stronger on a vocabulary item than they were at 25. Both changes are real. Neither shows up as a falling IQ, because the score asks how you compare with your peers, not with your younger self. The guide on fluid and crystallized intelligence explains why these two kinds of ability follow different paths.
What can make a score drop
A lower score on a second test usually has a plain cause: tiredness, distraction, a small screen, an unfamiliar format or ordinary measurement error, which on clinical tests is often around plus or minus 5 points at 95% (Wechsler, 2008). If you notice a real change in memory or thinking in daily life, that is a question for a doctor, not for an online test.
For the full picture, read IQ and age or at what age intelligence peaks.
Sources
- Intelligence quotient. Wikipedia. en.wikipedia.org/wiki/Intelligence_quotient
- Hartshorne, J. K., & Germine, L. T. (2015). Psychological Science, 26(4), 433-443. doi.org/10.1177/0956797614567339
- Salthouse, T. A. (2009). Neurobiology of Aging, 30(4), 507-514.
- Wechsler, D. (2008). WAIS-IV Technical and Interpretive Manual. Pearson.