In Steven Pinker's book The Sense of Style, he talks about the 'given-before-new' principle (most notably on pages 131–138). He states, '... people learn by integrating new information into their existing web of knowledge.' He also says this is a significant contributor to coherence in writing.
In his examples of good adherence to the 'given-before-new' principle, he often highlights the subject as the 'given' information, the object as the 'new' information. See this example from the book ('given' information highlighted in bold):
A man arrives from Corinth with the message that Oedipus's father has died .... It emerges that this messenger was formerly a shepherd on Mount Cithaeron, and that he was given a baby .... The baby, he says, was given to him by another shepherd from the Laius household, who had been told to get rid of the child.
I question what 'given' information really is. These, in my opinion, are obvious examples; the 'given' subjects refer back to information from the previous (or the same) sentences. There is little room for argument. But what happens when the examples aren't so cut and dried?
This resource states that 'given' information is anything that we assume to be familiar. This resource, on the other hand, says that 'given' information is anything that 'has already been mentioned in the text.'
Which is it? Is it both? If so, how do we define what is assumed to be familiar? How far does this stretch, and must 'given' information take the position of subject?
See these examples:
(1) Jake entered the room. At the far end of the room was a piano.
(2) Jake entered the room. Floorboards creaked with every step.
In Example 1, we'll say that 'the far end of the room' is 'given' information. The 'piano' is new information. The principle, I think, has been adhered to by fronting and inversion. The preposition containing 'the far end of the room' is at the front of the sentence. However, this is not a subject, so is it correctly following the principle? The limited examples provided by almost every resource I have read are not clear on this.
In Example 2, we use 'floorboards' as the subject of the second sentence. This subject has not been explicitly introduced before this, but we could say that the reader might assume a room has floorboards.
Looking at fiction novels, the principle is seemingly ignored quite often. Subjects with indefinite articles are common. Then again, it could be argued that the scope of 'given' information is expanded and we simply expect the reader to accept the information on the basis that they are immersing themselves in a narrative. The goal of the text is not always perfect cohesion.
This isn't surprising; to maintain perfect cohesion with such unclear rules would result in a book without style, restricted by sentences beginning with 'they,' 'he,' 'she,' 'it,' and so on.