Definition:
Sign languages are complete, natural human languages expressed in the visual-spatial modality — using handshapes, hand movement, location relative to the body, non-manual features (facial expressions, mouth movements, head position), and spatial grammar to convey the full range of human linguistic meaning. Sign languages are not universal (each Deaf community has its own language — ASL, BSL, LSF, DGS, Libras, JSL, etc.); not manually coded English or any other spoken language; not mime or gesture systems. They are independent linguistic systems that arose spontaneously within Deaf communities and are fully as complex and expressive as any spoken language. A signer of ASL and a signer of BSL cannot understand each other, despite both living in English-dominant countries — because ASL and BSL are different languages, not dialects of the same thing.
Linguistic Structure of Sign Languages
Phonology (cherology): Like spoken languages, sign languages have a sublexical structure. The components of signs — handshape, location, movement, orientation, and non-manual features — function analogously to phonemes; altering any component changes the meaning (minimal pairs exist).
Morphology: Sign languages use spatial grammar productively. ASL uses signing space to establish referents and then refers back to them with directional verbs — a rich morphological system without word endings.
Syntax: Word order in sign languages varies (ASL has more flexibility than spoken English; topic-comment is prominent). Classifiers function as productive morphological units encoding size, shape, and movement of referents.
Non-manual grammar: Facial expressions, head position, and mouth morphemes are grammatical — not emotional decoration. Raised eyebrows mark yes/no questions; furrowed brows mark content questions; head forward marks topicalization.
Sign Languages and Spoken Languages Are Separate Systems
Signed Exact English (SEE) and other manually coded systems are educational inventions that encode the grammar of spoken English through signs — they are not sign languages and are not used naturally by Deaf communities. Conflating these with natural sign languages is a common misconception.
Sign Language Acquisition
Deaf children of Deaf parents who are exposed to sign language from birth acquire it on the same developmental timeline as hearing children acquiring spoken language: babbling stages (manual babbling), first signs, two-sign combinations, and full grammatical competence by age 5–6. This acquisition timeline provided key early evidence for the modularity of language as a system independent of modality.
Written Forms
Several sign languages have written representations (SignWriting, HamNoSys, si5s for ASL) that encode visual-spatial signs in written symbols, enabling literacy in sign language itself.
History
De l’Épée (1760s): First formal Deaf school in Paris; laid the foundation for French Sign Language, which influenced ASL.
Stokoe (1960): Sign Language Structure — the foundational linguistic analysis of ASL; first proof that sign languages are full linguistic systems, overturning decades of oralist denial.
Klima & Bellugi (1979): The Signs of Language — comprehensive linguistic description of ASL phonology, morphology, and syntax.
Groce (1985): Everyone Here Spoke Sign Language — documented the case of Martha’s Vineyard where a hereditary Deaf population led to widespread signing throughout the hearing community.
Practical Application
- Sign language learning is language learning — ASL, BSL, and other sign languages are full foreign languages and should be learned with the same intensity and immersion strategies as any spoken language: sustained input, interaction, and SRS vocabulary support.
- Deaf community access is essential — like all languages, sign languages are best acquired through community immersion, not classroom study alone. Seeking Deaf community events, Deaf signers as conversation partners, and authentic video content is essential.
Common Misconceptions
“Sign languages are just visual versions of spoken languages.”
Sign languages are independent natural languages with their own grammar, vocabulary, and syntax that differ fundamentally from the surrounding spoken languages. ASL is not a visual encoding of English — its grammar is more similar to Japanese in some respects (topic-comment structure, spatial grammar) than to English.
“There is one universal sign language.”
There are over 300 documented sign languages worldwide. American Sign Language (ASL), British Sign Language (BSL), and Japanese Sign Language (JSL) are mutually unintelligible. Sign languages evolved independently in deaf communities, not from spoken languages.
Criticisms
Sign language research has historically fought for recognition of sign languages as “real” languages. Current critiques focus on the under-representation of sign languages in linguistic typology, the ethical issues around cochlear implants vs. sign language education for deaf children, and the risk of sign language endangerment as mainstreaming education reduces signing deaf communities.
Social Media Sentiment
Sign languages appear in language learning communities when learners express interest in learning ASL or other sign languages. Discussions often address misconceptions (universality, simplicity) and debate whether sign language learning follows the same principles as spoken L2 acquisition. The intersection of deaf culture and language learning is discussed with increasing awareness of deafness as a cultural identity.
Last updated: 2026-04
Related Terms
See Also
- Bilingual — Hearing children of Deaf parents (CODAs) are often bimodal bilinguals (sign + spoken language)
- Language Acquisition — Sign language acquisition parallels spoken language acquisition developmentally
- Sakubo
Research
1. Sandler, W., & Lillo-Martin, D. (2006). Sign Language and Linguistic Universals. Cambridge University Press.
Demonstrates that sign languages exhibit the same fundamental linguistic properties as spoken languages — providing evidence for language universals that transcend modality.
2. Emmorey, K. (2002). Language, Cognition, and the Brain: Insights from Sign Language Research. Lawrence Erlbaum.
Examines what sign language reveals about language processing and the brain — demonstrates that signed and spoken languages are processed by the same neural networks, confirming the biological basis of language regardless of modality.