title: Internal and external dynamics in language: evidence from verb regularity in a historical corpus of English.
abstract: Human languages are rule governed, but almost invariably these rules have exceptions in the form of irregularities. Since rules in language are efficient and productive, the persistence of irregularity is an anomaly. How does irregularity linger in the face of internal (endogenous) and external (exogenous) pressures to conform to a rule? Here we address this problem by taking a detailed look at simple past tense verbs in the Corpus of Historical American English. The data show that the language is open, with many new verbs entering. At the same time, existing verbs might tend to regularize or irregularize as a consequence of internal dynamics, but overall, the amount of irregularity sustained by the language stays roughly constant over time. Despite continuous vocabulary growth, and presumably, an attendant increase in expressive power, there is no corresponding growth in irregularity. We analyze the set of irregulars, showing they may adhere to a set of minority rules, allowing for increased stability of irregularity over time. These findings contribute to the debate on how language systems become rule governed, and how and why they sustain exceptions to rules, providing insight into the interplay between the emergence and maintenance of rules and exceptions in language.
authors.affiliation: Institute for Complex Systems (ISC-CNR), Roma, Italy.
authors.forename: Christine F
authors.initials: CF
authors.lastname: Cuskley
authors.affiliation: Sapienza University of Rome, Physics Department, Roma, Italy; Institute for Complex Systems (ISC-CNR), Roma, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Pugliese
authors.affiliation: Institute for Complex Systems (ISC-CNR), Roma, Italy; Sapienza University of Rome, Physics Department, Roma, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Castellano
authors.affiliation: Institute for Complex Systems (ISC-CNR), Roma, Italy; Sapienza University of Rome, Physics Department, Roma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Colaiori
authors.affiliation: Sapienza University of Rome, Physics Department, Roma, Italy; Institute for Scientific Interchange (ISI), Torino, Italy; Institute for Complex Systems (ISC-CNR), Roma, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Loreto
authors.affiliation: Institute for Scientific Interchange (ISI), Torino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tria
mesh_terms: D006801:Humans; D007802:Language; D014825:Vocabulary
references.citation: Nature. 2007 Oct 11;449(7163):713-6
references.pmid: 17928859
references.citation: Trends Cogn Sci. 2002 Nov 1;6(11):464-465
references.pmid: 12457896
references.citation: J R Soc Interface. 2012 Dec 7;9(77):3323-8
references.pmid: 22832364
references.citation: Trends Cogn Sci. 2002 Nov 1;6(11):456-463
references.pmid: 12457895
references.citation: PLoS One. 2010 Jan 20;5(1):e8559
references.pmid: 20098492
references.citation: Sci Rep. 2012;2:313
references.pmid: 22423321
references.citation: Proc Natl Acad Sci U S A. 2008 Aug 5;105(31):10681-6
references.pmid: 18667697
references.citation: Sci Rep. 2012;2:943
references.pmid: 23230508
references.citation: Science. 2011 Jan 14;331(6014):176-82
references.pmid: 21163965
references.citation: Cognition. 2003 Dec;90(2):119-61
references.pmid: 14599751