Spell-check myth: typos fell to 0.03%, wrong words rose

A 2020 UK study found spell-check cut dyslexic students' misspellings from 4.35% to 0.03% of words. It ran in the Journal of Writing Research in June 2020.

That is close to zero. But the same study found that wrong real words went up when spell-check was on.

So if you clear every red line and still find "form" where you meant "from," the tool did its job. It just has a blind spot. This piece shows where the gap is and how to close it in two minutes.

The myth: a clean spell-check means a clean email

Most of us treat the red line as the final check. No red lines, so the email is safe to send. It feels like a pass mark.

Spell-check works by looking up each word on its own. If the word is in its dictionary, it stays quiet. So "their" for "there" sails through, and so does "mange" for "manage."

University of Iceland researchers put it plainly in a May 2020 workshop paper (LREC READI, May 2020). A simple dictionary lookup will not spot a real word used in the wrong place. They cite Rello and colleagues (2015), who found nearly 20% of dyslexic spelling errors are real-word errors.

So what for you: a clean spell-check only tells you the words exist. Checking they are the right words is a separate step.

What the 2020 spell-check study found

Researchers at Oxford Brookes University tested 18 dyslexic college students and 18 peers (Journal of Writing Research, June 2020). Each person wrote two short essays in Microsoft Word. One essay had spell-check on, and one had it off.

The essays were a little under 300 words each, about the size of a long work email. Here is what changed:

• Dyslexic students, spell-check off: 4.35% of words misspelled.
• Dyslexic students, spell-check on: 0.03% of words misspelled.
• Peers, spell-check off: 0.82% of words misspelled.
• Peers, spell-check on: 0.17% of words misspelled.

With spell-check on, the dyslexic group left fewer misspellings than their peers. Spelling skill also stopped predicting how many errors were left. And the quality of the writing did not change either way.

So what for you: keep spell-check on, always. For non-words, it closes the gap with your colleagues almost fully.

Spell-check can add wrong words

The same study found a catch. In it, real-word errors went up for dyslexic writers when spell-check was on. They rose to 0.98% of all words (Journal of Writing Research, June 2020).

In plain numbers, that was 2 to 3 wrong words per essay. In the other conditions, it was about 1 per essay. Without spell-check, both groups made about 1 real-word error in every 300 words.

The authors think the extra errors came from the suggestion list. A writer clicks a word that looks close but means something else.

One essay talked about "attempting mental arrhythmia." The authors say the writer likely meant arithmetic.

You have probably done this. You type a word you can't spell, right-click it, and pick the first option that looks about right. The red line goes away, so it feels fixed.

So what for you: the riskiest moment is the click on a suggestion. Slow down there, and nowhere else.

Older spell-checkers did worse

An earlier study by Pedler (2001) tested the spell-check in Word 97 on 577 misspellings. It could help fix 55% of them, as summed up in the June 2020 paper. Another 20% were real-word errors, which it never flagged.

That older study has limits. Only one of the writers in it was known to be dyslexic, and the texts were old.

The 2020 authors say newer Word versions show a short list of 3 words. Many come with synonyms next to them. That helps you check the meaning before you click.

So the tool has got better at spelling. The real-word gap is still there, because a dictionary can't know what you meant.

So what for you: trust spell-check for spelling. Use a second check for meaning.

A 2-minute check that catches wrong words

Your eyes fill in what you meant to write. Your ears are harder to fool. When a voice reads "mental arrhythmia" out loud, it sounds wrong right away.

Word has this built in. In Word, open the Review tab and pick Read Aloud (Microsoft Support, checked November 2026). On Windows, Ctrl+Alt+Space starts it too.

Ctrl+Space plays or pauses it. On a Mac, Read Aloud needs Office 2019, Office 2021 or Microsoft 365.

Use this short routine on anything that matters:

• Fix the red lines first, and read the synonym next to each suggestion before you click.
• Play the whole text back once at normal speed.
• Stop at any word that sounds odd, and fix it on the spot.
• Read the subject line and the first line twice. Those get read the most.

If you want a voice outside Word, our text-to-speech tools guide compares the options. If tone worries you as much as typos, try the email tone checker. It reads your draft and flags lines that may land badly.

So what for you: make the read-back your last step before send. It takes about as long as one more silent re-read.

When the re-reading never stops

Maybe you already do all of this. You still read each email three times and send it with a knot in your stomach. That habit has a cost, even when it stays hidden.

The masking cost calculator puts a number on it. Enter your salary and your workarounds, and it tells you what that time costs per year.

If you have never been assessed and this sounds familiar, an assessment can tell you what is going on. Only a formal assessment can give you that answer. It also gives you a report you can use to ask for support at work.

So what for you: if the checking eats an hour a day, find out why. A name for it opens the door to tools and support.

Does spell-check help dyslexia at work? The call

Yes, and by a lot. The 2020 study shows spell-check takes dyslexic misspellings close to zero. Turn it on everywhere you write, in email and in documents.

But stop using the red line as your final check. The words it misses are real words in the wrong place, and the suggestion list can add more. Add a 2-minute read-back with Read Aloud to catch them.

Here is what to do this week. Pick your next important email.

Clear the red lines, then play it back once before you send. Count how many wrong words you catch. That number tells you if the habit is worth keeping.

So what for you: keep spell-check on, and add one read-back before you send. Start with your next email.

Common questions

Does spell-check help people with dyslexia?

Yes, by a lot. In a 2020 UK study, dyslexic students' misspellings fell from 4.35% to 0.03% of words. The study ran in the Journal of Writing Research in June 2020.

Why does spell-check miss some of my mistakes?

It checks each word against a dictionary. If you type a real word in the wrong place, such as "form" for "from," it stays quiet. Nearly 20% of dyslexic spelling errors are real-word errors (Rello and colleagues 2015, cited May 2020).

Can spell-check make my writing worse?

It can add wrong words if you click the wrong suggestion. In the 2020 study, dyslexic writers made 2 to 3 real-word errors per essay with spell-check on. Without it, they made about 1 (Journal of Writing Research, June 2020).

What is the fastest way to catch wrong words?

Listen to your text. In Word, open the Review tab and pick Read Aloud. On Windows, Ctrl+Alt+Space also starts it (Microsoft Support, checked November 2026).