Thursday, July 6, 2017

What's the relationship between language and thought? The Optimal Semantic Expressivity Hypothesis

(This post came directly out of a conversation with Alex Carstensen. I'm writing a synthesis of others' work, but the core hypotheses here are mostly not my own.)

What is the relationship between language and thought? Do we think in language? Do people who speak different languages think about the world differently? Since my first exposure to cognitive science in college, I've been fascinated with the relationship between language and thought. I recently wrote about my experiences teaching about this topic. Since then I've been thinking more about how to connect the Whorfian literature – which typically investigates whether cross-linguistic differences in grammar and vocabulary result in differences in cognition – with work in semantic typology, pragmatics, language evolution, and conceptual development.

Each of these fields investigates questions about language and thought in different ways. By mapping cross-linguistic variation, typologists provide insight into the range of possible representations of thought – for example, Berlin & Kay's classic study of color naming across languages. Research in pragmatics describes the relationship between our internal semantic organization and what we actually communicate to one another, a relationship that can in turn lead to language evolution (see e.g., Box 4 of a review I wrote with Noah Goodman). And work on children's conceptual development can reveal effects of language on the emergence of concepts (e.g., as in classic work by Bowerman & Choi on learning to describe motion events in Korean vs. English).

All of these literatures provide their own take on the issue of language and thought, and the issue is further complicated by the many different semantic domains under investigation. Language and thought research has taken color as a central case study for the past fifty years, and there is also an extensive tradition of research on spatial cognition and navigation. But there are also more recent investigations of object categorization, number, theory of mind, kinship terms, and a whole host of other domains. And different domains provide more or less support to different hypothesized relationships. Color categorization seems to suggest a simple model where it's faster to categorize different colors because the words help with encoding and memory. In contrast, exact number may require much more in the way of conceptual induction, where children bootstrap wholly new concepts.

The Optimal Semantic Expressivity Hypothesis. Recently, a synthesis has begun to emerge that cuts across a number of these fields. Lots of people have contributed to this synthesis, but I associate it most with work by Terry Regier and collaborators (including Alex!), Dedre Gentner, and to a certain extent the tradition of language evolution research from Kenny Smith and Simon Kirby (also with a great and under-cited paper by Baddeley and Attewell).* This synthesis posits that languages have evolved over historical time to provide relatively optimal, discrete representations of particular semantic domains like color, number, or kinship. Let's call this the optimal semantic expressivity (OSE) hypothesis.**