Why research sign language?

Before the late 1970s, Nicaragua had no shared sign language. Deaf children and adults communicated at home through homesign — individual gesture systems created for everyday interaction — but there was no common language across families.

That began to change when new special-education programs brought deaf students together for the first time. In classrooms and schoolyards, young signers started combining and reshaping their homesigns to communicate with one another. Within just a few years, a new, shared system began to take form — one that grew more structured, more regular, and more expressive as children interacted.

By the end of the 1980s, these first signers were fluent in what had become a full-fledged language. The next generation of deaf children learned it naturally, as any child learns their native tongue. Today, Nicaraguan Sign Language (LSN) continues to evolve, providing an extraordinary record of a language’s birth — a living demonstration that linguistic structure can arise wherever human minds seek to connect.

Nicaraguan Sign Language (LSN) offers a rare opportunity to observe a language in the process of emerging. By studying LSN, researchers can track how linguistic structure develops over time: how individual gestures and homesigns evolve into shared vocabulary, consistent word order, and complex grammatical constructions.

LSN also lets scientists examine the roles of social interaction, peer learning, and intergenerational transmission in shaping language. It provides empirical evidence about the human capacity for language — including the cognitive biases and constraints that guide grammar formation — and informs broader questions about how languages originate, stabilize, and adapt in communities.

Before deaf children in Nicaragua or elsewhere meet other deaf peers, each may invent a private gesture system to communicate with family — a homesign system. These systems include consistent handshapes, word orders, and combinatorial patterns, going beyond simple pantomime. They are spontaneous creations, arising whenever a child lacks access to a conventional language.

Studying homesign allows researchers to observe what humans contribute to language independently of social input. It reveals innate tendencies, cognitive biases, and structural preferences that guide the formation of linguistic systems. By examining homesign, we can better understand the human capacity for language, the building blocks of grammar, and the conditions under which languages emerge.

American Sign Language is a rich, fully developed natural language used by Deaf communities across the U.S. and parts of Canada. It did not emerge from English, but from the blending of local village sign systems (Marthas Vineyard Sign Language) and homesign systems with French Sign Language (LSF) in early 19th-century schools for the Deaf (e.g., The American School for the Deaf in Connecticutt).

ASL has evolved through everyday use — shifting handshapes, regional variations, slang, and stylistic innovation. Its linguistic structure is remarkably systematic, with phonological features (handshape, movement, location, orientation) and its own syntax, morphology, and prosody.

Research on ASL has transformed linguistics itself: showing that human language does not depend on sound, but on the mind’s ability to encode meaning and structure, no matter the modality.

Studying ASL provides insight into the human capacity for language beyond the spoken modality. It shows that linguistic structure—phonology, grammar, and syntax—can emerge and operate in the visual-manual channel.

Research on ASL has broadened our understanding of universal properties of language and the ways modality influences grammar. Investigating ASL also informs questions about language acquisition, variation across communities, and the cognitive mechanisms that underlie structured communication.

Sign languages challenge — and confirm — many theories about what’s universal in human language. Despite being visual and spatial, sign languages display the same fundamental linguistic properties as spoken ones: hierarchical structure, recursion, and grammatical categories like noun and verb.

But the visual-manual modality also introduces new possibilities: simultaneous expression, iconic mapping, and spatial grammar. Studying these helps researchers refine what belongs to “language” itself versus what reflects its sensory channel.

The convergence of structure across modalities supports a central insight: the human capacity for language is flexible, but deeply constrained by our shared cognitive architecture.

Automatic recognition and translation fall short of human signing, which relies on space, facial expression, motion, and cultural context. Human interpreters also bring judgment, empathy, and adaptability that no algorithm can match.

Where AI shines is in research, resource building, and increasing visibility. Many sign languages lack datasets, dictionaries, or annotated corpora. Machine learning can organize visual data, analyze linguistic features, and accelerate documentation, while also bringing signed language into the spotlight and creating opportunities for wider exposure.

In this way, AI amplifies human expertise, supporting linguists, educators, and Deaf communities. The goal isn’t automation, but empowerment — expanding tools to understand, preserve, and celebrate the richness of signed communication.

Research on sign languages often begins with questions about the nature of human language itself—its structure, origins, and cognitive foundations. Yet the process of studying language is never neutral. The categories we build, the examples we highlight, and even the terms we use to describe linguistic systems shape how these languages and their communities are perceived.

Scientific inquiry depends on precision, but it also benefits from awareness—of how our theoretical frameworks interact with the lived realities of the people whose languages we study. Holding both in view allows research to remain empirically grounded while also attuned to the broader contexts in which linguistic knowledge circulates. In this way, the science of language remains both rigorous and responsive: advancing understanding while acknowledging its human dimensions.