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.91.012808b,
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}
}