Abstract

A defining characteristic of human language is hierarchical recursion. Recursive loops (e.g. relative clauses) in sentences can either be embedded in the center of a sentence or cross each other. It is still unknown why in Indo-European languages the possibility for  center-embedded (CE) recursion seems ubiquitous  as in The boy A₁ the dog A₂ chases B₂ falls B₁ (A₁A₂B₂B₁), whereas crossed-dependent (CD) orderings of recursion hardly ever occur (A₁A₂B₁B₂). In both structures, serially encoded words (e.g. boy and dog) must be retrieved and bound to later upcoming words (chases and falls). The exceptional rarity of CD as compared to CE grammars is surprising considering that the latter produce dependent elements at longer distances than the former. We propose that the preponderance of CE can be explained by item retention and retrieval mechanisms of serial recall combined with word binding operations (e.g. A_i is Subject Noun of B_i) specific for language comprehension. Our account explains that backward retrieval (retrieving dog (A₂) first, and boy (A₁) next, as in CE) optimizes memory performance as compared to forward retrieval. We design two Retrieval and Binding Performance (RBP) functions, for CE and CD, and show by numeric comparison that RBP for CE is larger than for CD for a given sentence. Moreover, independent serial recall data support this difference in efficacy between the two strategies, under conditions that mimic sentence processing. We propose that CE is better molded to human memory than CD, which might explain why CE has prevailed during language evolution.

About the speaker

Fenna Poletiek, visiting fellow, AIAS, Aarhus University

Free of charge - All are welcome