Fresh eyes - why?

Writers are often told to put their work away (in a drawer, or similar) after writing the first draft, and return to it with 'fresh eyes'.  In 'On Writing', Steven King suggests that it should be months rather than weeks (King, 2001).

Pile of Papers 

by Biblioteekje

Does anyone know why this works? (assuming it does - surely all those millions of writers can't be wrong!)

I expect it is partly due to reading becoming more automatic with exposure, causing mistakes to be missed.  As mentioned in a previous post, the mind likes to take shortcuts.  An obvious shortcut is to read what you remember, rather than going to the trouble of looking at the words and letters on the page!

Another aspect is that when reading, the eyes do not actually take a text in one word at a time, letter by letter.  The saccades - quick eye movements - that a reader makes leads to some words being perceived in more detail than other.  This tends to be the 'content' words which contain the meaning of the sentence - verbs, nouns etc - rather than 'function' words such as pronouns (e.g. 'of' in the example below).

Eye movements across 2 lines of text

It can be clearly see why typos are going to be easy to miss, especially in function words such as one of my common mistakes - 'the' instead of 'they'.

But more important that proof reading, a writer needs to look at the ideas of a text, the meaning, the pace and the emotion.  All of these can be looked at anew.  I don't know of any research in this area, but I'd like to hear about it.  My own experience is that a lot of the raw, personal nature of a piece of writing goes with the passage of time, and it is much more like looking at someone else's work - something that you can look at and respond to objectively.

King, S. (2001).  On Writing: A Memoir of the Craft.  New English Library.