Is Structure Dependence Shaped for Efficient Communication?: A Case Study on Coordination (2410.10556v1)

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.

• The paper demonstrates that structure-dependent syntactic reductions yield superior communicative efficiency by balancing surprisal and parsability.
• The study employs artificial probabilistic grammars and RNNGs to quantify efficiency through controlled experiments on predictability and parsability.
• The findings challenge traditional linguistic theories by linking structural features with functional pressures, offering new directions for language research.

Investigating Structure Dependence in Natural Language and Communication Efficiency

This paper presents a paper that posits the presence of structure-dependent syntactic properties in language as a consequence of communicative efficiency through an exploration focusing on coordinate structures. The primary question considered by the authors is whether these structure-dependent properties, typically integral to natural language, can indeed be aligned with the hypothesis of efficient communication—a hypothesis that suggests linguistic universals are shaped by functional pressures for communication efficiency.

Overview of the Study

The authors challenge the conventional wisdom that structure dependence is purely a domain-specific feature of human language divorced from communicative principles. They explore three artificial languages that vary based on syntactic reduction operations: (i) a structure-dependent reduction akin to natural languages, (ii) a language with no reduction operations, and (iii) a language featuring linear reduction operations. The communicative efficiency of these languages is quantified using Recurrent Neural Network Grammars (RNNGs), examining both predictability and parsability as measures of linguistic simplicity and informativeness, respectively.

Experiment Design and Methodology

The experiment employs artificial probabilistic context-free grammars to create controlled syntactic environments. The languages exhibit distinct word order patterns and reduction types. The approach to quantifying communicative efficiency involves examining the predictability, defined by word-by-word surprisal, and parsability, gauged through syntactic structure recovery. The objective function elegantly combines these two aspects, allowing the authors to gauge efficiency through various trade-off parameters.

The usage of RNNGs aligns with recent advances in cognitive modeling, offering an apparatus that captures both LLMing and syntactic parsing. RNNGs provide a robust framework for estimating the conditional entropy of sentence structures directly from configurations of the artificial languages.

Results and Discussion

A significant contribution of this paper is the empirical demonstration that languages with structure-dependent reductions are more communicatively efficient for a broad range of trade-off parameters. The results are clear: only when balancing simplicity and informativeness, as encapsulated by a communicative efficiency function, do structure-dependent languages stand out. Predictability and parsability, taken independently, favored the respective counterfactual languages; however, their combination highlighted the intrinsic advantage of structure dependence.

The authors offer meaningful discussion regarding why structure dependence reduces parsing ambiguity without overly complicating prediction tasks—an alignment that underscores an efficiency unseen in linear or no-reduction scenarios. The implications reach beyond immediate grammatical observations, prompting a reconsideration of long-held beliefs in linguistic theory that have historically prioritized computational efficiency over communicative function.

Implications and Future Directions

This paper opens paths for re-evaluating linguistic theories that have traditionally viewed structure-dependent features as domain-specific and separate from communication. It suggests a more intricate relationship where linguistics may be informed by communication-oriented, domain-general principles. While the paper uses artificial languages for controlled experiments, it sets the stage for further investigation using natural language corpora like Universal Dependencies, promising rich future explorations into agreement, movement, and other syntactic phenomena.

Conclusion

In sum, this paper deftly explores a nuanced inquiry into linguistic universals, bridging the gap between structural linguistic properties and communicative imperatives. It elucidates a compelling perspective that structure dependence in natural language can plausibly be explained through principles centered on communicative efficiency, adding a vital dimension to our understanding of language evolution and structure.