The actual message of the text was that everyone can read it, not '55%'. I suppose what this may prove is that "only 55% of people read both the title and the text, and consider if they actually contradict each other".
Snopes says the origin of the whole thing seems uncertain, so all of it may just be made up. But I've seen this elsewhere, and have never seen a lot of people saying "I can't understand it!"
On edit: following through the Snopes links, it seems there was a bit of research, by a PhD candidate at Nottingham University, which may be where this came from, because he wrote a letter to New Scientist about it:
Reibadailty29 May 1999 by Graham Rawlinson, Aldershot, Hampshire
You report that reversing 50-millisecond segments of recorded sound does not greatly affect listeners' ability to understand speech (In Brief, 1 May, p 27).
This reminds me of my PhD at Nottingham University (1976), which showed that randomising letters in the middle of words had little or no effect on the ability of skilled readers to understand the text. Indeed one rapid reader noticed only four or five errors in an A4 page of muddled text.
This is easy to denmtrasote. In a puiltacibon of New Scnieitst you could ramdinose all the letetrs, keipeng the first two and last two the same, and reibadailty would hadrly be aftcfeed. My ansaylis did not come to much beucase the thoery at the time was for shape and senqeuce retigcionon. Saberi's work sugsegts we may have some pofrweul palrlael prsooscers at work.
The resaon for this is suerly that idnetiyfing coentnt by paarllel prseocsing speeds up regnicoiton. We only need the first and last two letetrs to spot chganes in meniang.
http://www.newscientist.com/article/mg1622... And, after the claim that Cambridge University was involved,
someone there did the snooping, and got a comment from Rawlinson:
...
My conclusions, and these are open to question of course, were that:
Letter features are processed through a route of letter classification/identification.
Middle letter identification proceeds largely independently of position.
Higher level units seem to be significant only for the beginnings and endings of words.
Information from the middle letters may operate via a sampling/probability system (rather than absolute accuracy). That is, you can have sufficient letters, even though in the wrong position, for the brain to 'recognise' the word.
http://www.mrc-cbu.cam.ac.uk/people/matt.d... 
