Editing Origin of language (section)

=== Number representation ===
In one particular study, rats and pigeons were required to press a button a certain number of times to get food. The animals showed very accurate distinction for numbers less than four, but as the numbers increased, the error rate increased.<ref name="Hauser2002" /> In another, the [[Primatology|primatologist]] [[Tetsuro Matsuzawa]] attempted to teach chimpanzees Arabic numerals.<ref>{{Cite journal |last=Matsuzawa |first=Tetsuro |date=1985 |title=Use of numbers by a chimpanzee |url=https://www.nature.com/articles/315057a0 |journal=[[Nature (journal)|Nature]] |volume=315 |issue=6014 |pages=57–59 |bibcode=1985Natur.315...57M |doi=10.1038/315057a0 |pmid=3990808 |s2cid=4361089}}</ref> The difference between primates and humans in this regard was very large, as it took the chimps thousands of trials to learn 1–9, with each number requiring a similar amount of training time; yet, after learning the meaning of 1, 2 and 3 (and sometimes 4), children (after the age of 5.5 to 6) easily comprehend the value of greater integers by using a [[successor function]] (i.e. 2 is 1 greater than 1, 3 is 1 greater than 2, 4 is 1 greater than 3; once 4 is reached it seems most children [[Eureka effect|suddenly understand]] that the value of any integer ''n'' is 1 greater than the previous integer).<ref>{{Cite journal |last1=Cheung |first1=Pierina |last2=Rubenson |first2=Miriam |last3=Barner |first3=David |date=February 2017 |title=To infinity and beyond: Children generalize the successor function to all possible numbers years after learning to count |url=https://www.sciencedirect.com/science/article/abs/pii/S0010028516302006 |journal=Cognitive Psychology |volume=92 |pages=22–36 |doi=10.1016/j.cogpsych.2016.11.002 |pmid=27889550 |s2cid=206867905 |via=Science Direct}}</ref> Put simply, other primates learn the meaning of numbers one by one, similar to their approach to other referential symbols, while children first learn an arbitrary list of symbols (1, 2, 3, 4...) and then later learn their precise meanings.<ref>{{Cite journal |last=Carey |first=Susan |year=2001 |title=Cognitive Foundations of Arithmetic: Evolution and Ontogenisis |url=http://www.wjh.harvard.edu/~lds/pdfs/carey2001c.pdf |url-status=dead |journal=Mind and Language |volume=16 |issue=1 |pages=37–55 |doi=10.1111/1468-0017.00155 |archive-url=https://web.archive.org/web/20130725071406/http://www.wjh.harvard.edu/%7Elds/pdfs/carey2001c.pdf |archive-date=25 July 2013 |access-date=13 January 2014}}</ref> These results can be seen as evidence for the application of the "open-ended generative property" of language in human numeral cognition.<ref name="Hauser2002" />