[zedadex]

> The reason we don't see our own typos is because what we see on the screen is competing with the version that exists in our heads

Which is why reading text backwards can help to find typos, or so I've heard. (Typos tend to jump out at me, even in my own writing.)

[kmschaal]

I can second this; from my experience reading text backwards greatly helps with finding typos. The reason for this is presumably that in this way it is easier to force our brain to look at every single word in isolation. In normal (forward) reading we process more than one word at a time.