(In the study people were asked to close their eyes and mentally count the passing of 120 seconds. They all counted too quickly.
On average, men and women in the 15 to 29 age group counted down the 120 seconds in 115 seconds. In the 30 to 49 age group they took 96 seconds, but the over-50s took just 86 seconds. This meant the oldest group perceived time as passing 25 per cent more quickly than the youngest did.
The researchers believe it is possibly due to age-related changes in levels of brain chemicals involved in concentration and memory, both of which are involved in estimating the passage of time.
I think it’s more likely that at 50+ you simply have more to do, and feel you have less time to do it in.)
PS -If you want to be able to count in seconds more accurately, say the number plus the word elephants.