A predictability-distinctiveness trade-off in the historical emergence of word forms

It has been proposed that language evolves under the joint constraints of communicative expressivity and cognitive ease. We explore this idea in the historical emergence of word forms. We hypothesize that new word forms that enter the lexicon should reflect a trade-off between predictability and distinctiveness. An emergent word form can be highly predictable if it efficiently reuses elements from the existing word forms, resulting in low cognitive load. An emergent word form should also be sufficiently distinctive from the existing lexicon, facilitating communicative expressivity. We test our hypothesis by examining the properties of 34,478 emergent word forms over the past 200 years of Modern English. We show how word forms at future time t + 1 are bounded statistically between n-gram generated word forms (highly predictable) and slang words that are outside the standard lexicon (highly distinctive) at time t. Our work supports the view of cognitive economy in lexical emergence.