Bouma shapes and readability: How word shape impacts accessible design

When you’re creating content for social media or your website, it’s easy to focus on how it looks. Fonts, colours, layout — we all want our content to reflect our brand. But when it comes to accessibility, there’s a deeper layer than visual style. It’s about how the brain reads.

Let’s talk about bouma shapes — and why they’re key to creating clear, inclusive content.

What are bouma shapes?

The term bouma shape comes from psychologist Herman Bouma, who studied how we recognise words while reading. A bouma is the overall visual outline a word forms — a kind of silhouette that allows us to recognise it quickly.

Rather than reading letter-by-letter, our brains scan the familiar shape of the word. That’s why we can often read jumbled sentences, as long as the first and last letters are intact — the word’s bouma is still recognisable.

Take the word readability. In sentence case, it forms a long, distinct shape with a mix of ascenders and descenders. But write it in ALL CAPS or use a decorative font, and that shape disappears — slowing the reader down.

Why bouma shapes matter in accessible content design

Bouma shapes are especially important in the fast-paced world of online reading. When word shapes are distorted by poor font choices — like all caps, overly tight spacing, or script fonts — reading becomes harder.

This creates unnecessary cognitive load for everyone, but it’s particularly challenging for:

– People with dyslexia

– Readers with visual processing differences

– Mobile users scanning content quickly

Preserving bouma shapes makes your content easier to scan and understand — which is essential for both accessibility and engagement.

What research tells us: The Rayner study on word recognition

In 2001, psychologist Keith Rayner published a paper titled “How Psychological Science Informs the Teaching of Reading.” The research found that:

– We don’t read by decoding one letter at a time

– Readers process words more efficiently when word shape is preserved

– Disrupting this shape — with unusual casing or irregular formatting — slows reading and reduces comprehension

The takeaway from the study? Design choices that distort word shape can unintentionally exclude or frustrate your audience.

Bouma shapes vs parallel letter recognition: what’s the difference?

While bouma theory explains how we scan for word shapes, it’s important to mention the more modern theory: parallel letter recognition.

This model suggests we recognise all the letters in a word at the same time, then use that information — along with context — to identify the word. It’s supported by cognitive science and is now considered more accurate than the word shape model alone.

But here’s the key point:

Even with parallel processing, familiar word shapes still support faster, more fluent reading. Disrupting those shapes with stylised fonts or inconsistent casing slows us down — especially for readers with accessibility needs.

So from a content design perspective, both theories lead us to the same conclusion:

Clarity matters. Shape matters. Font choice matters.

How to design for better readability

Here are some quick, practical ways to preserve word shapes and improve accessibility in your content:

– Use sentence case instead of all caps for body text

– Choose clean, sans serif fonts with balanced spacing

– Avoid decorative or script fonts for captions, carousels, or large blocks of text

– Test your text on mobile to ensure shape and legibility hold up across screen sizes

– Keep spacing generous and consistent to support scanning

Good accessible design starts with readability — and preserving word shape is a huge part of that.

Final thoughts: design with the brain in mind

Whether your audience reads every word or skims your content on the go, their experience is shaped by how words look. Designing with bouma shapes in mind supports better accessibility, better comprehension — and better connection with your audience.

Next up in the series: Parallel letter recognition

We’ll dig into how this model updates the bouma theory — and what it means for how we design accessible content today.