Addictive or Subtractive?

Yakushima: the way we count
 

What body parts do you use for counting?

In western societies its common to count using primary hand, thumb first, then fingers before repeating the process on the next hand.

In Japan the digits are counted out of the primary hand and then counted back – addictive then subtractive.

Whilst both methods work well up to ten, I can’t help thinking that the Japanese+ method is more scaleable in that the user is conditioned to think beyond what is physically present. If this is the case then what would be the cultural driver for counting to larger sums?

Yakushima: the way we count