On favour of humans, people have usually seen the numbers thousands to millions of times in their lifetimes, while chimps would have seen them few dozens of times at best. So "training the same time" for humans and chimps is def misleading, would love to see this with an abstract or uncommon characters like Japanese (for a Western audience).
四,六,八 is "four, six, eight" in English. These are the names of the numbers, not the numbers themselves. In Japanese they write the numbers the same as in English ("4, 6, 8")
> In Japanese they write the numbers the same as in English ("4, 6, 8")
Modern Japanese has two numeral systems - Arabic and Chinese. The Arabic numerals were introduced to Japanese relatively recently (only in the modern period). In pre-modern Japanese, only the Chinese numerals existed. In contemporary Japanese, Arabic numerals are more common, but Chinese numerals are still used in some contexts (especially texts written vertically)
I don't know about you, but I write my 1 in just one stroke of the pen. Also I use a space as a thousands separator, and you need to write 一万 in Japanese for 10 000, not just 万 by itself. That makes for a closer game:
一 / 1 (one stroke vs one)
十 / 10 (two strokes vs two)
一万 / 10 000 (or 10K) (four strokes vs five)
When you get to numbers like 5462, there's no contest versus 五千四百六十二.
