Is Structure Dependence Shaped for Efficient Communication?: A Case Study on Coordination

TL;DR

This study investigates whether the structure dependence property in language arises from the need for efficient communication, demonstrating that languages with structure-dependent operations are more communicatively efficient.

Contribution

It provides evidence that structure dependence can be explained by communicative efficiency, challenging the view that it is solely domain-specific and irreducible.

Findings

Languages with structure-dependent reduction are more efficient.

Structure dependence enhances communicative efficiency.

Linear reduction languages are less efficient.

Abstract

Natural language exhibits various universal properties. But why do these universals exist? One explanation is that they arise from functional pressures to achieve efficient communication, a view which attributes cross-linguistic properties to domain-general cognitive abilities. This hypothesis has successfully addressed some syntactic universal properties such as compositionality and Greenbergian word order universals. However, more abstract syntactic universals have not been explored from the perspective of efficient communication. Among such universals, the most notable one is structure dependence, that is, the existence of grammar-internal operations that crucially depend on hierarchical representations. This property has traditionally been taken to be central to natural language and to involve domain-specific knowledge irreducible to communicative efficiency. In this paper, we challenge the conventional view by investigating whether structure dependence realizes efficient communication, focusing on coordinate structures. We design three types of artificial languages: (i) one with a structure-dependent reduction operation, which is similar to natural language, (ii) one without any reduction operations, and (iii) one with a linear (rather than structure-dependent) reduction operation. We quantify the communicative efficiency of these languages. The results demonstrate that the language with the structure-dependent reduction operation is significantly more communicatively efficient than the counterfactual languages. This suggests that the existence of structure-dependent properties can be explained from the perspective of efficient communication.