If you've spent time in AAC circles, you've heard the term "core vocabulary." It comes up constantly in therapy sessions, AAC trainings, and parent groups. But what does the research actually say about it? Is the emphasis on core words justified, or is it just a trend?
The short answer: it's well justified. The research on core vocabulary is some of the most consistent and practically applicable evidence in the entire AAC field. Here's what it shows.
Defining Core vs. Fringe Vocabulary
Core vocabulary refers to a small set of high-frequency words that appear across all contexts, speakers, and situations. These are mostly pronouns, verbs, adjectives, and prepositions: words like "I," "want," "more," "go," "not," "that," "it," "on," "big."
Fringe vocabulary refers to context-specific words that appear less frequently but carry topical meaning. These are mostly nouns: "cookie," "dinosaur," "playground," "grandma."
The distinction matters because of how dramatically their usage frequencies differ.
The Numbers
The foundational research on core vocabulary in AAC comes from frequency analyses of natural language. Several key studies have established the same basic pattern:
Banajee, DiCarlo, and Stricklin (2003) analyzed the language of toddlers aged 2 to 3 years in daycare settings. They found that a set of approximately 250 words accounted for the vast majority of words used in conversation. Most of these were core words, not nouns.
Yorkston, Dowden, Honsinger, Marriner, and Smith (1988) conducted one of the earlier frequency analyses for AAC purposes. They found that the 100 most frequently occurring words covered approximately 60% of all words spoken in their samples. The top 500 covered roughly 80%.
Cross, Baker, Klotz, and Badman (1997) studied vocabulary use across adults and children with and without disabilities. Their findings confirmed that a small core set is remarkably stable across ages, contexts, and ability levels.
The pattern is consistent: a small number of words do most of the work. And those words are overwhelmingly core, not fringe.
Why Core Words Are More Powerful Than Nouns
The frequency data is compelling, but the real argument for core vocabulary goes deeper than how often words appear.
Generativity
Core words are generative. They combine with each other and with fringe words to produce an almost unlimited number of messages. "Want" + any noun = a request. "Not" + any word = a negation. "More" + any activity = a continuation request.
A child who knows 10 core words and 5 nouns can produce dozens of unique messages. A child who knows 15 nouns can label 15 things.
Baker, Hill, and Devylder (2000) demonstrated this in their analysis of AAC vocabulary systems. They argued that core vocabulary gives AAC users the ability to generate novel utterances across contexts, while fringe-only approaches limit users to pre-programmed messages.
Context independence
Nouns are tied to contexts. "Cookie" is relevant at snack time but useless on the playground. "Swing" is relevant at the park but useless at dinner.
Core words work everywhere. "More" is useful during meals, play, reading, music, bath time, and every other activity. "Stop" applies to any unwanted stimulus. "Help" works in any situation where the child is struggling.
This means core words give your child communication tools that travel with them from setting to setting, while nouns need to be constantly expanded to cover new environments.
Motor planning efficiency
This point is especially relevant for AAC users. On a communication device, each word lives at a specific screen location. With consistent placement, users develop motor plans (muscle memory patterns) that let them navigate quickly without visually searching for each word.
Core words are used so frequently that motor plans develop rapidly. A child who uses "more" 20 times a day will develop a fast, automatic motor plan for that word within weeks. A noun used once a day may never develop that automaticity.
AAC systems like SabiKo that keep core words in consistent positions support this motor planning benefit.
What the Research Says About Teaching Core Words
Knowing that core words are important is one thing. The question for families and therapists is: does explicitly teaching core words lead to better outcomes?
Boenisch and Soto (2015)
Boenisch and Soto analyzed the oral vocabulary of typically developing English-speaking school-age children. They confirmed that a small set of core words dominated everyday speech across all the children studied. This matters for AAC because it shows that the core vocabulary pattern is not an artifact of simplified communication systems. It reflects how natural language actually works. The same high-frequency words that drive spoken communication should drive AAC vocabulary design.
This finding reinforces a key point: AAC systems built around core words aren't limiting. They're mirroring the structure of natural language.
Clendon and Andersen (2017)
Clendon and Andersen presented a case study of a literacy-based AAC intervention for a beginning communicator. The intervention incorporated core vocabulary within a literacy framework, and the participant showed increases in both the frequency and diversity of communication, using more words in more combinations across more contexts.
Trembath, Balandin, and Togher (2007)
Trembath and colleagues studied vocabulary selection for children using AAC across Australian English and Italian contexts. Their findings reinforced that a core vocabulary approach provides a stable foundation across different languages and cultural settings. The same high-frequency words appeared consistently, supporting the idea that core vocabulary is not language-specific but a universal feature of how people communicate.
The Counterargument: When Nouns Matter
The research strongly supports prioritizing core vocabulary, but that doesn't mean nouns are unimportant. There are legitimate reasons to include fringe vocabulary in an AAC system:
Personal relevance. A child's pet's name, their favorite character, their teacher's name. These words carry emotional significance and can motivate device use.
Specificity. "Want that" gets the message across, but "want pizza" is clearer and faster. Once core words are established, adding high-frequency nouns reduces ambiguity.
Academic participation. In school settings, children need topic-specific vocabulary to participate in lessons. A unit on weather requires "rain," "sun," "cloud," etc.
Cultural connection. Specific cultural foods, holidays, family terms, and traditions have no core word equivalent.
The research-supported approach isn't core words instead of nouns. It's core words first, nouns added strategically based on the individual's needs and interests.
Practical Implications
For families and therapists, the research on core vocabulary suggests several actionable guidelines:
1. Start with core words. When setting up a new AAC system, the first words on the board should be core: more, stop, want, go, help, not, yes, no, I, that.
2. Keep core words in consistent positions. Motor planning depends on spatial consistency. Don't rearrange the home screen.
3. Model core words across contexts. Use "more" during meals, play, reading, and bath time. The more contexts a child encounters a word in, the faster they'll generalize it.
4. Add nouns based on motivation. When you add fringe vocabulary, choose words the child is actually interested in. A list of "most common nouns" is less useful than a list of "things this specific child cares about."
5. Teach word combinations early. Once a child has 3 to 5 core words, start modeling two-word combinations. Core words combine naturally: "want more," "not that," "go out," "help me."
6. Measure communication functions, not just word count. A child who uses 5 core words to request, reject, comment, and greet is communicating more effectively than a child who uses 20 nouns only to label.
The Bottom Line
The research is clear and consistent: core vocabulary should be the foundation of any AAC system. A small set of high-frequency words provides more communication power than a large set of nouns. Core words generalize across contexts, support diverse communication functions, develop strong motor plans, and combine into novel messages.
This doesn't mean nouns don't matter. It means they should be layered on top of a solid core vocabulary foundation, not used as the starting point.
Download SabiKo free and give your child a communication system built on research-backed core vocabulary.
References
- Banajee, M., DiCarlo, C., & Stricklin, S.B. (2003). Core vocabulary determination for toddlers. Augmentative and Alternative Communication, 19(2), 67-73.
- Baker, B., Hill, K., & Devylder, R. (2000). Core vocabulary is the same across environments. Paper presented at the Technology and Persons with Disabilities Conference, CSUN.
- Yorkston, K.M., Dowden, P.A., Honsinger, M.J., Marriner, N., & Smith, K. (1988). A comparison of standard and user vocabulary lists. Augmentative and Alternative Communication, 4(4), 189-210.
- Cross, R.T., Baker, B., Klotz, L., & Badman, A.L. (1997). Static and dynamic vocabulary considerations for multi-level AAC systems. Paper presented at the ISAAC Conference.
- Boenisch, J., & Soto, G. (2015). The oral core vocabulary of typically developing English-speaking school-age children. Augmentative and Alternative Communication, 31(1), 51-64.
- Clendon, S.A., & Andersen, R.G. (2017). Literacy-based AAC intervention: A case study. Journal of Special Education Technology, 32(4), 199-210.
- Trembath, D., Balandin, S., & Togher, L. (2007). Vocabulary selection for Australian English and Italian children using augmentative and alternative communication. Journal of Intellectual & Developmental Disability, 32(4), 291-301.