This is the Secret to speed reading.
Speed reading is based on this concept - Phrase Reading.
After years of reading, the human mind doesn't need to read every letter, but can read the word as a whole.
Due to years of reading, your mind recognizes entire words as a single entities.
In speed reading, realizing that the mind recognizes words as single entities unto themselves, and does not require one to focus on every individual letter, they came to the realization that with just a small amount of practice, one can train themselves to read phrases.
By phrases, they are referring to groups of 3 to 5 sequential words.
The mind can focus on those phrases in much the same way you recognize (focus on) the words with out analyzing each letter.
You focus on a 3 to 5 word group, and interpret / recognize the phrase, much the way you recognize individual words,
with out individually focusing on each of the letters.
In other words, you recognize phrases, with out focusing on each of the individual words. (with out individually interpreting each word).
You focus instead, on a small group of words at a time.
Instead of recognizing groups of letters as words, you recognize groups of words as phrases.
One can practice phrase reading by reading the news paper, or pretty much any publication.
After a while recognizing phrases, becomes natural and easy.
The claim is that because reading phrases has fewer pauses, you retain more.
As opposed to reading each individual word, in which you stop to interpret each word, on a word by word basis, you only interpret on a phrase by phrase basis.
This results in 3 to 5 times fewer pauses, and interpretation processes taking place.
The claim is that fewer pauses to interpret, increases retention, and comprehension.
This also, in theory, increases speed by up to 3 to 5 times. (300 to 500 percent)

Phrase Reading Example:

A sentence like this:

In the event you get this letter, preheat the oven to 450 at 5PM.

Gets broken in to phrases like this:

In the event         you get this letter          preheat the oven         to 450 at 5PM.

Instead of reading / interpreting 14 words, you read / interpret 4 phrases.
These phrases can be read / interpreted (with practice) at the speed you would have read only the same number of individual words.
Eventually the mind interprets phrases, much the same way, and with the same degree of efficiency, that it already interprets words during reading.