As we age we all experience a natural decline in intelligence, but our IQs stay very much the same(unless something like dementia occurs). This is because you are compared to others of the same age, as to how you rank with them.
Most online tests are non-verbal(fluid).Even if data is taken and used, it’s usually not to the extent that scores are adjusted for age. Those of us of a semi advanced age(euphemistically speaking) are going to have a significantly lower score compared to what our age adjusted score would be. That is because the average age of people taking such tests is probably <35-40.
Fluid intelligence drops much more quickly. Kaufman reveals that it “peaks at ages 20–24 (100), drops gradually to 99 (25–34) and 96 (35–44) before starting a rollercoaster plunge to 91 (45–54), 86 (55–64), 83 (65–69), 79 (70–74), and 72 (75+).”
It seems weird to me. If you score lower on the same tasks as someone who is 20 years younger, how can you be said to be as intelligent? The next step seems to me to correct the IQ for variation in test scores in everyone. We will all get a medal with 100 on it.
As my thread title suggests there is a natural cognitive decline that we all experience. I don’t in any way believe the 66 year old is as mentally sharp as a 46 year old me was. A 46 year old less intelligent than I was at that age will become a person less intelligent than I am when he/she/non binary reaches 66.
In summary, age adjustment in IQ scoring is a standard practice designed to provide a fair and accurate measure of an individual’s cognitive abilities relative to others in their age group. It’s not about being ‘smarter’ than someone of a different age5.