What is sign language?

Signed language is a language articulated in visual-spatial modality. Primarily developed and used by culturally Deaf people, the language is as sophisticated and complex as any speech (vocal-aural) language.

Brain controls language development

Myth: Speech is correlated with language development.

Fact: Research studies show that language acquisition (L1) milestones in sign language are on a similar timeline as found in speech from babbling to the two-word stage and beyond (Petitto). This shows evidence that the brain controls maturational language development regardless of the modality (signing or speech).

Brain doesn't tell the difference

Studies show that processing ASL (or another signed language) activates the same linguistic regions of the left brain as spoken languages. As renowned neuroscientist Dr. Petitto famously noted, the brain does not differentiate between hands and lips, which is evidence that speech isn't central to language.

Signed language isn't a version of spoken language

A signed language is a language of its own, independent from spoken languages. For examples, Ameslan (American Sign Language) and Auslan (Australian Sign Language) are not signed versions of English and they aren't based on the English language.

Similar to spoken languages, signed languages have their own grammatical rules, syntax, phonology, morphology, other linguistic features and unique complexities.

Sign language isn't a substitute for speech language

Sign language and speech language are amodal, which means language is independent from modality. Language is brain-based.

Sign language is not gestural nor pictorial

Sign language doesn't comprise a standardized system of manual gestures. Otherwise, wouldn't it be a bit weird to say speech language comprises a standardized system of vocal gestures, eh?

Language comprises symbols (words), grammar, and sentence structure. Despite some iconicity — which does not differ from speech with some iconic sounds or "onomatopoeia" — ASL signs/words are as abstract as those of any spoken languages.

Sign language isn't universal

While it's a common sense to Deaf people, hearing people aren't aware of. Contrary to common belief among hearing speakers, sign language isn't universal nor international — similar to speech language. Signed languages worldwide are as distinct as, for example, the English and Japanese spoken languages.

Signing and speech are visual-spatial and vocal-aural modalities, respectively. Language is brain-based.

Oh yeah, by the way, ASL has a writing system.


Basically, signed language is a language articulated in visual-spatial modality, whereas spoken language is a language articulated in vocal-aural modality.

Signed and spoken languages process in the same linguistic regions of the brain, including a similar timeline of language acquisition, according to linguistics and neuroscience studies. As for modalities, they process in different parts of the brain.

Languages in signed and spoken versions are not the same. They are independent. E.g. ASL is not English.

Posted 2012, updated 2022.

Related posts

What is ASL (American Sign Language? Is sign language even a language?

How do hearing people think of sign language?

New to sign language? "Where do I start?" or "How do I start learning sign language?" This ASL Rookie guide lists some selected links to the tutorials for ASL beginners to get started and keep rolling. It may be a useful review for intermediate-level learners and ASL students as well.

Some tutorial pages are a mix of free and premium versions. Access to premium content and links below are available in the PatronPlus subscription. More links/posts will be added from time to time.

Expressing needs and wants

  1. Making commands or requests

Talking about activities

  1. Frequency of time: how often?

Are you able to carry everyday conversations in ASL? Are you a student in the intermediate levels and beyond, who wishes to boost up your signing skills? You've come to the selected tutorial series. (Some premium content are available to PatronPlus membership.)

Stories, poems, performance arts, etc. in sign language.

This documentation project follows a child's language acquisition, literacy development, and phonological acquisition in sign language, specifically ASL, from newborn to age five in a natural native-ASL environment and visual culture.