Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
Aaclltuy, taht is not ture. It smees lkie it oghut to be, but taht is in lagre prat due to olny vrey sghilt mginnug dnoe to the txet. If you try haderr, and alppy a mroe aeggirssve taafimnoorrstn to the txet, you wlil fnid taht it is no legnor esay to raed the txet. Eaceillpsy ntoe how the legnor wdors in tihs salmpe are far haderr to raed tahn tsohe taht are sehortr; it is the oceeimnnprse of the salml, facinnotul wdors taht ldens ielstf to esay iaeeinoprrtttn, and legnor wdors (mroe haeilvy maeglnd) bcemoe ecdeegilnxy dcffiilut caeeghllns to pluzze out waht tehy wree oagiillnry ideenntd to reeenprst.
(I didn't opt to randomly choose the middle letters, but instead sorted them, using reverse alphabetical order when the word came out the same. This makes some words insanely difficult--functional and interpretation are impossible to pick out so mangled, and I wrote the entire paragraph before pasting it).
If you thought that was too hard to read, here's the original:
Actually, that is not true. It seems like it ought to be, but that is in large part due to only very slight munging done to the text. If you try harder, and apply a more aggressive transformation to the text, you will find that it is no longer easy to read the text. Especially note how the longer words in this sample are far harder to read than those that are shorter; it is the omnipresence of the small, functional words that lends itself to easy interpretation, and longer words (more heavily mangled) become exceedingly difficult challenges to puzzle out what they were originally intended to represent.
FWIW I still found the heavily mangled version fairly easy to read, maybe a 20-30% slowdown max and it got easier as I went.
I speedread though so maybe it's because I'm already used to not actually focusing on letters and taking in the gestalt instead. It's kind of like how it's easy to tell the equality of two sets written in different orders up to about size 4, and past that it gets tricky. This is why the classic tick mark system uses 4 ticks and then a slash for the fifth too.