The research behind core vocabulary (and why 200 words matter)

When you first see an AAC board built around core vocabulary, it can feel counterintuitive. There are not many pictures of nouns. No grid full of foods, animals and toys. Instead there are small, plain-looking words: "go," "want," "more," "that," "not," "you." A parent could be forgiven for wondering why the app is not teaching their child the names of things first.

The answer is one of the more settled findings in the whole field of communication. A surprisingly small set of words does most of the talking, for all of us, all the time. This article explains what core vocabulary is, walks through the research behind it, and shows why starting with roughly 200 words is one of the most evidence-based decisions an AAC app can make.

AAC, for anyone new to the term, stands for Augmentative and Alternative Communication: the tools and strategies that give a voice to people who cannot rely on speech alone.

What "core vocabulary" actually means

Core vocabulary is the small set of high-frequency words we use constantly, no matter what we are talking about. Words like "want," "go," "stop," "more," "that," "you," "it," "not," "like" and "help." They are mostly not nouns. They are the verbs, pronouns, and little connecting words that hold sentences together.

The opposite is fringe vocabulary: the specific, topic-based words that change depending on the subject. "Dinosaur," "trampoline," "spaghetti," "Grandma." Fringe words are personal and important, but each one only comes up some of the time, when its particular topic does.

Here is the key insight. Core words are few in number but used over and over. Fringe words are vast in number but each used only occasionally. So if you want to give someone the most communication for the smallest amount of learning, you start with core.

The research: a small set of words, most of the talking

This is not a hunch or a fashion. It rests on language-sampling research that goes back decades.

Two pieces of work are cited most often. Vanderheiden and Kelso (1987) and Baker and Hill (2000) are foundational references for core vocabulary in AAC. The finding that emerges from this body of research is strikingly consistent: roughly 80 per cent of what we say is communicated using only the 200 or so most basic words, and a set of around 200 to 400 core words covers about 80 per cent of everyday communication across age, setting, gender and disability.

Read that last part again, because it is the remarkable bit. The same small core does most of the work regardless of who is speaking, how old they are, where they are, or whether they have a disability. The core is shared. It is one of the closest things communication research has to a universal pattern.

That is why "200 words" is not an arbitrary round number. It is roughly the point at which a vocabulary becomes powerful enough to express most of what a person needs to say across a whole day, while still being small enough to learn deeply.

Why this changes how you teach AAC

Once you accept the research, a lot of practical decisions follow.

Depth beats breadth at the start

If 200 core words do most of the talking, then teaching those 200 words really well is more valuable than teaching 2,000 nouns shallowly. A child who can reliably reach "want," "more," "stop" and "go" can act on their whole world. A child who only has nouns can label, but struggles to request, refuse, comment or direct.

Core words work across every situation

A noun like "biscuit" is useful at snack time. A core word like "more" is useful at snack time, in the park, during play, at bath time, and in the middle of a tantrum. Because core words are not tied to a topic, every minute spent learning one pays off across the entire day.

It supports real sentences, not just naming

Communication is not a list of nouns. It is requesting, refusing, questioning, joking, arguing and commenting. Those functions are built almost entirely from core words. Starting with core gives a child the building blocks of actual conversation, not just the ability to name what they see.

Where the buttons live matters as much as which words they are

There is a second, quieter finding alongside the vocabulary research, and it is just as important. For a core word to do its job, a person has to be able to find it fast, without searching. That speed comes from motor planning: the automatic, almost unconscious movements a person builds up through repetition, the same way an experienced typist no longer looks at the keyboard.

Motor planning only develops if the word stays in the same place. Every time a learned button moves, the automatic movement breaks and the person is back to searching with their eyes. So a research-based vocabulary is only half the answer. The other half is keeping it still.

This is exactly how Sayella is built. The app puts a research-based core vocabulary front and centre, and grows it through an approach called Progressive Language: new words are revealed inside a grid that stays put. The layout does not reflow, and a learned button never moves. New vocabulary fades in around the core words a child already knows, so the motor patterns they build on those high-frequency words are protected as the vocabulary expands.

In other words, Sayella respects both halves of the research. The right words, kept in the right place, for as long as the person uses them.

Putting the research to work at home

You do not need to be a therapist to use this. A few simple ideas, grounded in the same evidence:

• Model core words across the day. Press "more," "go" and "stop" yourself, in lots of different situations, so your child sees how flexible they are.
• Do not wait for perfect. Core words let a child communicate functions like requesting and refusing early, long before a big vocabulary is in place.
• Keep the layout stable. Resist the urge to reorganise the board. Consistency is doing real clinical work even when nothing visible is changing.
• Let fringe grow around core, not instead of it. Add the personal nouns your child loves, but keep core at the centre where it belongs.

Where you have a speech and language therapist involved, they can tailor all of this to your particular child.

Frequently asked questions

Isn't it strange to start with words like "go" instead of "Mummy"?

It feels strange, but it is well evidenced. Core words like "go," "want" and "more" can be used in almost any situation, so they unlock far more communication, far sooner, than a handful of nouns. Personal nouns absolutely matter, and they grow in around the core over time.

Where do the "200 words" and "80 per cent" figures come from?

From language-sampling research in AAC, with Vanderheiden and Kelso (1987) and Baker and Hill (2000) among the most-cited sources. The consistent finding is that around 200 to 400 core words account for roughly 80 per cent of everyday communication across age, setting and ability.

Does core vocabulary mean my child will only ever have a small vocabulary?

Not at all. Core is the starting point and the stable centre. Fringe vocabulary grows around it over time, and many communicators go on to spelling and text. The point of starting with core is to build the most communication, fastest, on the firmest foundation.

How does keeping buttons still relate to the research?

The vocabulary research tells you which words to prioritise. Motor planning research tells you to keep them in a consistent place so a person can find them automatically. Sayella honours both by keeping a learned button from ever moving as the vocabulary grows.

---

Sayella is in pre-launch and built around this evidence from the ground up. If you would like to start modelling core words with your child today, you can get our free printable core boards, designed around the same research-based, fixed-position approach, and join the early access list to be among the first families in when we open the doors.