Typos, Swypos and Missspellings

How English is transcribed has moved from writing on stone tablets/papyrus/paper, to typing on a type writer/word processor/keyboard to our swiping on an iphone/android/hololens. With each of those transitions correcting for mistakes when reading the text has become harder and harder.


Even though English has a set way of spelling things (called orthography) misspellings don’t normally prevent us from understanding when someone misspells a word. In “He went through the boat’s hach” the misspelling of hatch doesn’t make the sentence significantly harder to understand for a native speaker. In fact I when choosing that sentence I had to double check that “hach” was not an alternative spelling of “hatch”.

Our brains instinctively come up with sounds (phonemes) to match the written letters (graphemes). “hatch”’s IPA (the standard on how to represent phonemes) is hætʃ. While “hach” does not have a IPA entry (since it’s a misspelling) a native speaker would also map “hach” to hætʃ. Since both “hatch” and “hach” map to the same pronunciation the native speaker knows what you mean i.e. a small door in a boat.

hatch mapping


Assuming we know how to correctly spell “hatch” we could still mistype the sentence and end up with a typo. “He went through the boat’s hatcg” Again though it’s normally easy for the reader to mentally correct for this. “hatcg” isn’t a word so our brain’s automatically try to think of words that are edit distance one from it. In addition ‘g’ is right next to ‘h’ on a QWERTY keyboard and most people have a good idea of what keys are close together. This doesn’t help the mistypist if they were using a DVORAK keyboard but if they’re using a DVORAK keyboard they have larger problems.

Our brain’s error correction fails however when the typo creates another real word. Without more context you don’t know that “He went through the boat’s catch” means he entered the boat and not he was looking at their fish.

catch mapping

These are called atomic typos because although they change a single letter they also completely change the meaning of the sentence which makes them much harder to catch.


With autocorrect software and swiping on mobile phone keyboards errors similar to atomic typos are even more common and difficult to correct. The software has to guess what word was actually meant. I call these swypos.

When I swiped out “He went through the boat’s hatch” I instead got “He went through the boat’s hastily” which is much further from the original meaning than the already confusing atomic typo is.

There’s a concept called Levenshtein Distance which is a measure of how far apart 2 words are. The atomic typo of hatch->catch only has an Levenshtein Distance of 1 since you only have to change a single letter. hatch->hastily has a distance of 4 since you have to add 2 letters and change 2 letters.

What makes this even worse is that since this sentence isn’t grammatically correct a grammar checker will tell you to fix it. But the smallest change that fixes the grammar is “He went through the boats hastily” which gives the sentence a completely different meaning.

To sum up English misspellings are usually sound very similar to the intended word which makes them easy native speakers to correct for. Typos are harder but still understandable since most people use a QWERTY keyboard. Swypos, when people swiping at their phone’s screens have their text autocorrected to something completely different can be impossible to guess because they always form a real word and require guessing at the autocorrect algorithm which are customized to each phone and user.