Comment by roeles
In agile circles I have seen this exercise:
Have two people sit next to each other, each with a blank piece of paper and a pen.
Have them both simultaneously write down the numbers from 1 to 1: one time in decimal, one time in roman numbers and one time as letters of the alphabet (a=1, b=2...)
One person goes about it system by system (first decimal, then Roman... ). The other goes about it number by number (1,I,A,2,II,B...)
Time them both and compare their times.