Publications

@inproceedings{evolang11_119,
title = {The Emergence Of Rules And Exceptions In A Population Of Interacting Agents},
author = {Christine Cuskley and Vittorio Loreto},
editor = {S.G. Roberts and C. Cuskley and L. McCrohon and L. Barceló-Coblijn and O. Fehér and T. Verhoef},
url = {http://evolang.org/neworleans/papers/119.html},
year = {2016},
date = {2016-01-01},
booktitle = {The Evolution of Language: Proceedings of the 11th International Conference (EVOLANGX11)},
abstract = {Rules are an efficient feature of natural languages which allow speakers to use a finite set of instructions to generate a virtually infinite set of utterances. Yet, for many regular rules, there are irregular exceptions. There has been lively debate in cognitive science about how individual learners acquire rules and exceptions; for example, how they learn the past tense of preach is preached, but for teach it is taught. In this paper, we take a different perspective, examining the dynamics of regularity and irregularity across a population of interacting agents to investigate how inflectional rules are applied to verbs. We show that in the absence of biases towards either regularity or irregularity, the outcome is determined by the initial condition, irrespective of the frequency of usage of the given lemma. On the other hand, in presence of biases, rule systems exhibit frequency dependent patterns in regularity reminiscent of patterns in natural language corpora. We examine the case where individuals are biased towards linguistic regularity in two ways: either as child learners, or through a memory constraint wherein irregular forms can only be remembered by an individual agent for a finite time period. We provide theoretical arguments for the prediction of a critical frequency below which irregularity cannot persist in terms of the duration of the finite time period which constrains agent memory.},
keywords = {cuskley, kreyon, language_dynamics, language_games, loreto, modeling, rules},
pubstate = {published},
tppubtype = {inproceedings}
}

@article{PhysRevE.91.012808,
title = {General three-state model with biased population replacement: Analytical solution and application to language dynamics},
author = {Colaiori, Francesca and Castellano, Claudio and Cuskley, Christine F. and Loreto, Vittorio and Pugliese, Martina and Tria, Francesca},
url = {http://link.aps.org/doi/10.1103/PhysRevE.91.012808},
year = {2015},
date = {2015-01-01},
journal = {Phys. Rev. E},
volume = {91},
pages = {012808},
publisher = {American Physical Society},
keywords = {castellano, colaiori, cuskley, language_dynamics, loreto, pugliese, tria},
pubstate = {published},
tppubtype = {article}
}

@article{Cuskley2015205,
title = {The adoption of linguistic rules in native and non-native speakers: Evidence from a Wug task},
author = {Christine Cuskley and Francesca Colaiori and Claudio Castellano and Vittorio Loreto and Martina Pugliese and Francesca Tria},
url = {http://www.sciencedirect.com/science/article/pii/S0749596X15000790},
doi = {http://dx.doi.org/10.1016/j.jml.2015.06.005},
issn = {0749-596X},
year = {2015},
date = {2015-01-01},
journal = {Journal of Memory and Language},
volume = {84},
pages = {205 - 223},
abstract = {Several recent theories have suggested that an increase in the number of non-native speakers in a language can lead to changes in morphological rules. We examine this experimentally by contrasting the performance of native and non-native English speakers in a simple Wug-task, showing that non-native speakers are significantly more likely to provide non -ed (i.e., irregular) past-tense forms for novel verbs than native speakers. Both groups are sensitive to sound similarities between new words and existing words (i.e., are more likely to provide irregular forms for novel words which sound similar to existing irregulars). Among both natives and non-natives, irregularizations are non-random; that is, rather than presenting as truly irregular inflectional strategies, they follow identifiable sub-rules present in the highly frequent set of irregular English verbs. Our results shed new light on how native and non-native learners can affect language structure.},
keywords = {castellano, colaiori, cuskley, experiment, kreyon, language_dynamics, loreto, pugliese, rules, Sociolinguistics, tria},
pubstate = {published},
tppubtype = {article}
}

@article{PhysRevE.91.012808b,
title = {General three-state model with biased population replacement: Analytical solution and application to language dynamics},
author = {Francesca Colaiori and Claudio Castellano and Christine F. Cuskley and Vittorio Loreto and Martina Pugliese and Francesca Tria},
url = {http://link.aps.org/doi/10.1103/PhysRevE.91.012808},
doi = {10.1103/PhysRevE.91.012808},
year = {2015},
date = {2015-01-01},
journal = {Phys. Rev. E},
volume = {91},
pages = {012808},
publisher = {American Physical Society},
abstract = {Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent-based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularise irrespective of their frequency, or a continuous transition occurs between a low-frequency state, where the lemma becomes fully regular, and a high-frequency one, where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behaviour may emerge, namely, a discontinuous transition in frequency. We introduce and solve analytically a very general class of three-state models that allows us to fully understand these behaviours in a unified framework. Realistic sets of interaction rules, including the well-known naming game (NG) model, result in a discontinuous transition, in agreement with recent empirical findings. We also point out that the distinction between speaker and hearer in the interaction has no effect on the collective behaviour. The results for the general three-state model, although discussed in terms of
language dynamics, are widely applicable.},
keywords = {castellano, colaiori, cuskley, kreyon, language_dynamics, language_games, loreto, modeling, naming_game, pugliese, tria},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Internal and External Dynamics in Language: Evidence from Verb Regularity in a Historical Corpus of English},
author = {Christine F. Cuskley and Martina Pugliese and Claudio Castellano and Francesca Colaiori and Vittorio Loreto and Francesca Tria},
url = {http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0102882},
year = {2014},
date = {2014-01-01},
journal = {PLoS ONE},
volume = {9},
publisher = {Public Library of Science},
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. © 2014 Cuskley et al.},
keywords = {castellano, colaiori, cuskley, language_dynamics, loreto, pugliese, tria},
pubstate = {published},
tppubtype = {article}
}