The "Globularization Hypothesis" of the Language-ready Brain as a Developmental Frame for Prosodic Bootstrapping Theories of Language Acquisition.

Aritz Irurtzun

doi:10.3389/fpsyg.2015.01817

Abstract

In recent research (Boeckx and Benítez-Burraco, 2014a,b) have advanced the hypothesis that our species-specific language-ready brain should be understood as the outcome of developmental changes that occurred in our species after the split from Neanderthals-Denisovans, which resulted in a more globular braincase configuration in comparison to our closest relatives, who had elongated endocasts. According to these authors, the development of a globular brain is an essential ingredient for the language faculty and in particular, it is the centrality occupied by the thalamus in a globular brain that allows its modulatory or regulatory role, essential for syntactico-semantic computations. Their hypothesis is that the syntactico-semantic capacities arise in humans as a consequence of a process of globularization, which significantly takes place postnatally (cf. Neubauer et al., 2010). In this paper, I show that Boeckx and Benítez-Burraco's hypothesis makes an interesting developmental prediction regarding the path of language acquisition: it teases apart the onset of phonological acquisition and the onset of syntactic acquisition (the latter starting significantly later, after globularization). I argue that this hypothesis provides a developmental rationale for the prosodic bootstrapping hypothesis of language acquisition (cf. i.a. Gleitman and Wanner, 1982; Mehler et al., 1988, et seq.; Gervain and Werker, 2013), which claim that prosodic cues are employed for syntactic parsing. The literature converges in the observation that a large amount of such prosodic cues (in particular, rhythmic cues) are already acquired before the completion of the globularization phase, which paves the way for the premises of the prosodic bootstrapping hypothesis, allowing babies to have a rich knowledge of the prosody of their target language before they can start parsing the primary linguistic data syntactically.

Highlights

THE GLOBULARIZATION HYPOTHESISAccording to a recent article in this journal by Boeckx and Benítez-Burraco (2014a), “much work in neurolinguistics has unintentionally emphasized the externalization component of language, since morpho-phonology is perhaps the easiest aspect to single out linguistic tasks, even if the word “syntax” was said to be the target of the relevant works
Boeckx and Benítez-Burraco (2014a,b) have advanced the hypothesis that our species-specific language-ready brain should be understood as the outcome of developmental changes that occurred in our species after the split from Neanderthals-Denisovans, and which resulted in a more globular braincase configuration in comparison to our closest relatives, who had elongated endocasts. They propose that even if factors like brain lateralization are important, the development of a globular brain is at the outset of our language faculty, and in particular, it is the centrality of the thalamus in a globular brain that allows its modulatory or regulatory role, essential for syntactico-semantic computations
As Boeckx and Benítez-Burraco (2014a) put it, “a proper characterization of the language-ready brain that does not recognize a central role to the thalamus is unlikely to be correct, for it would miss the critical engagement of the thalamus in regulating cortical activity

Summary

INTRODUCTION

According to a recent article in this journal by Boeckx and Benítez-Burraco (2014a), “much work in neurolinguistics has unintentionally emphasized the externalization component of language, since morpho-phonology is perhaps the easiest aspect to single out linguistic tasks, even if the word “syntax” was said to be the target of the relevant works. Boeckx and Benítez-Burraco (2014a,b) have advanced the hypothesis that our species-specific language-ready brain (a brain which is suited for acquiring natural languages) should be understood as the outcome of developmental changes that occurred in our species after the split from Neanderthals-Denisovans, and which resulted in a more globular braincase configuration in comparison to our closest relatives, who had elongated endocasts They propose that even if factors like brain lateralization are important, the development of a globular brain is at the outset of our language faculty, and in particular, it is the centrality of the thalamus in a globular brain that allows its modulatory or regulatory role, essential for syntactico-semantic computations In line with the prosodic bootstrapping hypothesis, languageacquiring babies will be able to use their early-acquired prosodic knowledge as a guiding principle for inferring the syntax of their target language the moment the syntactic ability develops

EARLY PHONOLOGICAL ABILITIES IN HUMAN INFANTS

THE “PROSODIC BOOTSTRAPPING” HYPOTHESIS

SYNTHESIS