I’ve always heard that the brain sees words as a whole, and as long the first and last letters match and the word is the same length, it will be read correctly. The company French Connection – United Kingdom that uses the abbreviation FCUK capitalizes on this. I came across a great example this week:

“i cdnuolt blveiee taht I cluod aulaclty
uesdnatnrd waht I was rdgnieg.
The phaonmneal pweor of the hmuan mnid.
Aoccdrnig to a rscheearch at Cmabrigde
Uinervtisy, it deosn’t mttaer in waht oredr the
ltteers in a wrod a re, the olny iprmoatnt tihng is
taht the frist and Isat ltteer be in the rghit pclae.
The rset can be a taotl mses and you can
sitll raed it wouthit a porbelm.
Tihs is bcuseae the huamn mnid deos not raed
ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh?
yaeh and I awlyas thought slpeling was ipmorantt”