dc.contributor.advisor | Smith, Kenny | en |
dc.contributor.advisor | Truswell, Robert | en |
dc.contributor.advisor | Culbertson, Jennifer | en |
dc.contributor.advisor | Kirby, Simon | en |
dc.contributor.author | Saldana, Carmen Catalina | en |
dc.date.accessioned | 2018-07-23T10:09:00Z | |
dc.date.available | 2018-07-23T10:09:00Z | |
dc.date.issued | 2018-11-28 | |
dc.identifier.uri | http://hdl.handle.net/1842/31395 | |
dc.description.abstract | Languages are culturally transmitted through a repeated cycle of learning and communicative
interaction. These two aspects of cultural transmission impose (at least) three interacting pressures
that can shape the evolution of linguistic structure: a pressure for learnability, a pressure
for expressivity, and a pressure for coordination amongst users in a linguistic community. This
thesis considers how these sometimes competing pressures impact linguistic complexity across
cultural time. Using artificial language and iterated learning experimental paradigms, I investigate
the conditions under which complexity in morphological and syntactic systems emerges,
spreads, and reduces. These experiments illustrate the interaction of transmission, learning and
use in hitherto understudied domains—morphosyntax and word order.
In a first study (Chapter 2), I report the first iterated learning experiments to investigate the
evolution of complexity in compositional structure at the word and sentence level. I demonstrate
that a complex meaning space paired with pressures for learnability and communication
can result in compositional hierarchical constituent structure, including fixed combinatorial
rules of word formation and word order. This structure grants a productive and productively
interpretable language and only requires learners to acquire a finite lexicon and a finite set of
combinatorial rules (i.e., a grammar). In Chapter 3, I address the unique effect of communicative
interaction on linguistic complexity, by removing language learning completely. Speakers
use their native language to express novel meanings either in isolation or during communicative
interaction. I demonstrate that even in this case, communicative interaction leads to more
efficient and overall simpler linguistic systems.
These first two studies provide support for the claim that morphological and syntactic complexity
are shaped by an overarching drive towards simplicity (or learnability) in language
learning and communication. Chapter 4 reports a series of experiments assessing the possibility
that the simplicity bias found in the first two studies operates at a different strength depending
on the linguistic level. Studies in natural language learning and in pidgin/creole genesis suggest
that while morphological variation seems to be highly susceptible to regularisation, variation
in other syntactic features, like word order, appears more likely to be reproduced. I test this
experimentally by comparing regularisation of unconditioned variation across morphology and
word order in the context of artificial language learning. I show that language users in fact
regularise unconditioned variation in a similar way across linguistic levels, suggesting that the
simplicity bias may be driven by a single, non-level-specific mechanism.
Taken together, the experimental evidence presented in this thesis supports the hypothesis
that the cultural and cognitive pressures acting on language users during learning and communicative
interaction—for learnability, expressivity and coordination—are at least partially
responsible for the evolution of linguistic complexity. Specifically, they are responsible for
the emergence of linguistic complexity which maximises learnability and communicative efficiency,
and for the reduction of complexity which does not. More generally, the approach
taken in this thesis promotes a view of complexity in linguistic systems as an evolving variable
determined by the biases of language learners and users as languages are culturally transmitted. | en |
dc.contributor.sponsor | other | en |
dc.language.iso | en | |
dc.publisher | The University of Edinburgh | en |
dc.relation.hasversion | Saldana, C. (2017). Data from ”Simplifying linguistic complexity: Culture and cognition in language evolution”, PhD dissertation, 2014-2017 [dataset]. The University of Edinburgh. Centre for Language Evolution. doi: 10.7488/ds/2235 | en |
dc.relation.hasversion | Saldana, Smith, Kirby & Culbertson (2017) Is the strength of regularisation uniform across linguistic levels? Proceedings of the 39th Annual Conference of the Cognitive Science Society. Austin, TX: Cognitive Science Society. | en |
dc.subject | language evolution | en |
dc.subject | linguistic complexity | en |
dc.subject | simplicity bias | en |
dc.subject | artificial language learning | en |
dc.subject | iterated learning | en |
dc.subject | interaction | en |
dc.subject | morphology | en |
dc.subject | syntax | en |
dc.title | Simplifying linguistic complexity: culture and cognition in language evolution | en |
dc.type | Thesis or Dissertation | en |
dc.type.qualificationlevel | Doctoral | en |
dc.type.qualificationname | PhD Doctor of Philosophy | en |