Structural and Functional Organizing Principles of Language: Evolving Theories

Abstract

1. Introduction The overall goal of this paper is to evaluate theories that attempt to address the organizing principles of language and review the development of these theories toward the integration of language within an interactive network of higher-level cognitive functions. Commencing with an overview of traditional concepts of lan-guage as modular, distinct, and innate, we focus firstly on areas that highlight the foundation of modularity theory including various module definitions and crite-ria, and applications of modularity in information processing and biological sys-tems. We also discuss challenges to the overall applicability of a modular system and limitations of modular models in dealing with adaptation, novelty, innate ver-sus learned, domain-general and domain-specific features, and developmental and age-related changes of cognitive organization. Prompted by the rapidly increasing amount of empirical data on the func-tional elements of the human brain, we then evaluate several major theories of cog-nition, including views that oppose modular organization and those that integrate modular and semi-modular views with topological modularity in simpler, and dy-namic integration in higher-level cognitive functions.Within this framework, mod-ular and non-modular components of linguistic knowledge, organizing principles of language viewed either as specific or derived from other systems, and concepts of language as one of the cognitive functions or the outcome of unique interactions among cognitive components are discussed. Emerging theories that integrate interactive network models support a cog-nitive architecture as a mosaic of domain-specific and domain-general processes involving both functional segregation and integration within a global neuronal workspace. Within this anatomically distributed workspace, the language func-tion represents unique interactions among cognitive components consistent with an organization that is task-dependent with a continuum between degrees of mod-ular and shared processing. As a higher-level, learning-based, and effortful cog-nitive process language transiently enlists a less modular organization for an effi-cient network configuration in interaction with several cognitive systems and the domain-general cognitive control/multiple-demand network. Traditional explanatory models considered the language faculty (FL) as an organ of the body determined by genetic endowment (Universal Grammar, UG), expe-rience, and possible design features, mainly centered around the concept of com-putational efficiency and conceptualized as third factor principles in subsequent theories. Some of these features, based on the initially assumed lack of difference in basic language capacity among contemporary humans, have also been consid-ered language (UG) and/or even organism (third factor principles) independent (Chomsky 2005, 2011). Earlier concepts also held language as different and distinct from other cognitive functions with considerations of UG as a specific language module or a modularized knowledge or element of the FL (Hauser et al. 2002). Modularity, originally an engineering notion of near-decomposability, refers to a system that is made of components whose workings are independent of each other and in which the modular structure allows parts to be modified without the whole system ceasing to function (Simon 1969). The concept of modularity includ-ing certain characteristic and/or necessary model features (Fodor 1983), and a mod-ular design was considered central in biology (Marr 1982) with a general modular theory also proposed for perception and cognition (Coltheart 1999). The modular organization hypothesis has been also linked historically to the claim that aspects of the human mind are innately specified (Fodor 1983, reviewed in Twyman & New-combe 2010). The integration of modular organization in certain biological areas such as development has high explanatory value. However, a strictly modular view is con-troversial in the cognitive sciences as it precludes complex processes such as asso-ciative learning, attention, working memory, or general intelligence that cut across domains (Shettleworth 2012). The assumption that much of the cognitive process-ing is modular was challenged early on by fMRI data of brain activation (Wojciulik et al. 1998), and studies of neurodevelopmental language disorders that proposed relative modularity that is only achieved after an extensive period of developmen-tal time (Bishop 1997, Karmiloff-Smith 2007). The widely different definitions of what constitutes a module remain controversial and the minimum criteria that are required for a system to be considered modular are unsettled (Twyman & New-combe 2010, Kaltenbach & Stelling 2012). Important theoretical challenges also re-main regarding function-centered decomposition of dynamic biological networks (Kaltenbach & Stelling 2012). The controversial issues include the integration of modular clusters in a larger-scale as modalities in the brain need to be both isolated and sufficiently connected for coherent functions (Gallos et al. 2012), questions as to how does a modular system deal with novelty (Anselme 2012), the innate and/or developmental nature of modularity (Thomas & Karmiloff-Smith 2002), the lack of one-to-one correspondence in function to structure mapping (Petersson et al. 2012), the relationship between domain-general and domain-specific cognitive processes (Meunier et al. 2010, Kitzbichler et al. 2011), the continuum between strictly mod-ular processing and degrees of task dependent shared processing (Borowsky et al. 2007), and functional specialization as a matter of discrete units or as a matter of degree (Kanwisher 2010).