# Memory limitations are hidden in grammar

## TL;DR

This paper investigates how memory limitations influence grammatical structures in human language, revealing that syntactic dependencies are optimized to reduce memory load, challenging the assumption of independence between grammar and cognitive constraints.

## Contribution

It demonstrates that memory constraints are embedded in grammatical descriptions, highlighting the importance of cognitive factors in linguistic theory.

## Key findings

- Average dependency distance is less than chance expectations.
- Memory limitations influence syntactic dependency structures.
- Grammatical models should incorporate cognitive constraints.

## Abstract

The ability to produce and understand an unlimited number of different sentences is a hallmark of human language. Linguists have sought to define the essence of this generative capacity using formal grammars that describe the syntactic dependencies between constituents, independent of the computational limitations of the human brain. Here, we evaluate this independence assumption by sampling sentences uniformly from the space of possible syntactic structures. We find that the average dependency distance between syntactically related words, a proxy for memory limitations, is less than expected by chance in a collection of state-of-the-art classes of dependency grammars. Our findings indicate that memory limitations have permeated grammatical descriptions, suggesting that it may be impossible to build a parsimonious theory of human linguistic productivity independent of non-linguistic cognitive constraints.