Optimal categorisation: ​the nature of nominal classification systems

Effective categorisation should be simple, to minimise cognitive load, and informative, to maximise communicative efficiency. Nominal classification systems (gender, classifiers) are a functional means of categorisation that vary enormously across languages, revealing a trade-off between simplicity and informativeness. Closely related Oceanic languages of Melanesia show staggering variation in their number and type of classifiers. How does the Iaai language carve up nouns into 23 semantic groups whilst the Merei language uses only two; and what implications do these vastly different systems have for the cognitive representations of their related concepts? We combined typological enquiry and psycholinguistic experimentation (free listing, card sorting, video vignettes, possessive labelling, eye tracking, storyboards, category training) comparing nominal classification systems in six Oceanic languages of Vanuatu and New Caledonia. We discuss how these experiments uncover the nature of nominal classification systems, comparing objective data across languages and experimental contexts to reveal a model for optimal categorisation.