Language Evolution and Computation Bibliography

[From SWAP.] The most common word length in the lexicon lies in the middle of the total range. The shortest words -- light V or CV monosyllables -- are necessarily few because a cross-product of the consonantal and vocalic phonemes generates only a small number of combinations. As length increases, the number of possible forms explodes, but fewer and fewer are actually used in any given language. Experimental and computational studies relate the sparsity of long forms to the fact that the likelihood of forms as determined by a stochastic parse decreases with length. This effect occurs because long forms have more subparts than short ones, and the likelihood of any given subpart is always less than 1.0. (Coleman and Pierrehumbert 1997, Frisch et al in press). The disadvantage that long forms have in achieving a high well-formedness score is a distinct phenomenon from the tendency of individual long words to have low token frequencies (though there may of course be some deep relationship between these characteristcs). In English, a morphologically impoverished language, the most common type of word is the disyllable.

[Notes.] This is a Monte Carlo simulation on the learnability of phonological constraints, based on the idea that the phonological grammar needs to be shared even if individuals have different words in their vocabularies.

We present a connectionist model that demonstrates how propositional structure can emerge from the interactions among the members of a community of simple cognitive agents. We first describe a process in which agents coordinating their actions and verbal productions with each other in a shared world leads to the development of propositional structures. We then present a simulation model which implements this process for generating propositions from scratch. We report and discuss the behaviour of the model in terms of its ability to produce three properties of propositions: (1) a coherent lexicon characterised by shared form-meaning mappings; (2) conventional structure in the sequences of forms; (3) the prediction of spatial facts. We show that these properties do not emerge when a single individual learns the task alone and conclude that the properties emerge from the demands of the communication task rather than from anything inside the individual agents. We then show that the shared structural principles can be described as a grammar, and discuss the implications of this demonstration for theories concerning the origins of the structure of language.