Participants made fewer errors and responded faster for small Chinese numerals than small Arabic numerals, especially for the numerals one, two and three (Fig. 2).
Second, even though the monkeys did not show increasing inaccuracy with increasing numeral magnitude, they did show slower reaction times for smaller numerical differences, as do humans (Moyer and Landauer 1967).
As shown in Fig. 2, participants made fewer errors and responded faster for small Chinese numerals (Error rates: Mean = 13.26%; RTs: Mean = 600.01 msec) than small Arabic numerals (Error rates: Mean = 32.23%; RTs: Mean = 640.22 msec) when they were presented at the parafoveal location, especially for the numerals one, two and three.
Small Chinese numerals showed smaller N400 (M = 4.92 µV) than that of Arabic small numerals (M = 3.85 µV); whereas large Chinese (M = 4.36 µV) and Arabic (M = 4.54 µV) numerals did not show such a difference (Fig. 4 A).
Nonetheless, such differences were not found between large Chinese and Arabic numerals, nor when small numerals were presented at the foveal location.
The upper limits of these Australian numeral systems most often varied between three, four, and five, the team reports this month in the Proceedings of the Royal Society B. Over time, even small numeral systems sometimes lost a numeral or two, but they mainly gained numerals yet not by plodding up the number line, one numeral after another.
We predict that participants' performances could be better for those multi-representational small Chinese numerals than single-representational Arabic numerals in the parafoveal condition.
The monkeys' equal choice behavior fell along the dots = digits identity line (dotted line) for small numbers, but at higher numerosities the monkeys tended to undervalue the dots compared to the numerals, as predicted by our calculation (Fig. 4b) based on their dots-vs-dots and numeral-vs-numeral choices.
In the current study, we will use this paradigm again to explore the possible behavioral and ERP differences between multi-representational small Chinese numerals and single-representational Arabic numerals, as well as their underlying mechanism.
