Yes, sign language is a form of AAC. The American Speech-Language-Hearing Association (ASHA) classifies manual signs as an “unaided” mode of augmentative and alternative communication, meaning they require only the body and no external tools or devices. That said, how sign language gets used in AAC practice often looks quite different from the full linguistic systems used by Deaf communities.
How Sign Language Fits Into the AAC Framework
AAC is an umbrella term for any communication method that supplements or replaces speech for people with severe expressive communication difficulties. It breaks down into two broad categories: unaided systems that use only the body, and aided systems that rely on external tools. Unaided AAC includes gestures, facial expressions, and manual signs. Aided AAC ranges from low-tech picture boards to high-tech speech-generating devices on tablets.
Sign language lands squarely in the unaided category. The American Academy of Pediatrics lists manual signs alongside gestures and body posture as AAC supports “that require nothing but your own body.” ASHA’s clinical guidelines specifically recommend signs or gestures as one AAC option for nonspeaking children on the autism spectrum.
Full Sign Language vs. Key Word Signing
There’s an important distinction between learning a complete sign language like ASL and using individual signs as a communication tool. When speech-language pathologists recommend “sign” as AAC, they often mean something closer to key word signing (KWS): using manual signs for the most important words in a sentence while speaking aloud at the same time. This is fundamentally different from ASL or other sign languages, which have their own grammar, syntax, and linguistic rules.
Key word signing systems sometimes borrow vocabulary from the local sign language, but some use a separate set of signs chosen specifically because they’re easier to recognize and remember. Research comparing these distinct sign sets to full sign language vocabulary found that the simplified versions tend to be more iconic, meaning the sign visually resembles what it represents. That higher recognizability can make the signs more accessible for people with intellectual disabilities or young children just beginning to communicate.
For children with conditions like childhood apraxia of speech, signs are typically used as a bridge. A child pairs a sign with a verbal attempt, and as their spoken language becomes clearer, most children naturally drop the signs on their own. In this context, signing acts as a prompt for speech rather than a replacement for it.
Who Benefits From Sign-Based AAC
Children and adults across a wide range of conditions use manual signs as part of their communication toolkit. The American Academy of Pediatrics identifies autism spectrum disorder, cerebral palsy, deafness, childhood apraxia of speech, developmental language disorder, dysarthria, stroke, traumatic brain injury, and voice disorders as diagnoses where AAC, including signing, can help. In practice, many people use signs alongside other modes. Studies of deaf children with additional learning disabilities found that most who used signs were communicating through single-word manual signs combined with gestures, body language, and low-tech AAC systems like picture boards.
For autistic children specifically, AAC use (whether signs, picture systems, or devices) has been linked to improved communication skills, fewer challenging behaviors, greater social participation, and stronger language development overall. Parents and caregivers report better relationships with their children and increased independence as additional benefits.
Does Signing Delay Speech?
A common worry is that teaching a child to sign will discourage them from learning to talk. The research points in the opposite direction. A study of deaf and hard-of-hearing children learning both ASL and spoken English found that ASL vocabulary size positively correlated with spoken English vocabulary size. Children with large ASL vocabularies were actually more likely to have spoken English vocabularies in the typical range for hearing children. The researchers found no evidence to support the recommendation that families avoid sign language, and noted that if a causal relationship exists between signing and spoken language, the effect appears to be positive rather than harmful.
Practical Limitations of Sign-Based AAC
Despite its benefits, signing as AAC comes with real-world challenges. The most obvious: the person you’re communicating with needs to understand the signs. A child who signs at home with trained family members may struggle to be understood by peers, teachers, or strangers. Aided systems like speech-generating devices produce audible output that anyone can understand, which gives them an advantage in public settings.
Motor demands are another consideration. Forming signs requires fine motor control that some children and adults with physical disabilities may not have. Conditions affecting hand coordination, muscle tone, or movement planning can make signing difficult or impractical.
There’s also the broader issue of AAC abandonment. Research estimates that 30% to 50% of AAC users eventually abandon or significantly underuse their systems. The main barriers aren’t about the tools themselves but about the environment: attitudes of professionals, family members, and society, as well as personal factors like socioeconomic status and cultural context. For unaided systems like signing, fewer families and professionals report direct experience compared to high-tech options like tablet-based speech apps, which may reflect both shifting preferences and gaps in training.
How Signing Compares to Other AAC Options
No single AAC method works best for everyone, and many people use a combination. Here’s how signing stacks up against the main alternatives:
- Sign-based AAC (unaided): Always available, no equipment to charge or carry, supports language development. Limited by the listener’s knowledge of signs and the user’s motor abilities.
- Picture-based systems (low-tech aided): Visual symbols on boards or in binders that a user points to. Understandable without special training, portable, and inexpensive. Can be slow for complex messages and requires carrying physical materials.
- Speech-generating devices (high-tech aided): Apps or dedicated devices that produce spoken output. Universally understood, capable of generating complex language. Requires charging, can be expensive, and may be unavailable if the device breaks or is forgotten.
Many speech-language pathologists recommend a “total communication” approach, combining multiple methods so a person always has a way to express themselves regardless of the situation. A child might use signs at home, a picture board at school, and a tablet app in the community. The goal is communication access, not loyalty to a single system.