Texts can be seen as having layers. From low to high these layers comprise
Upper layers can have emergent features absent from lower ones (and vice versa). For example
Interpretation is not a straightforward progression from lowest to highest level. A higher level interpretation can provoke a re-interpretation of a lower level. Often the lower levels (the choice of font, color, etc) is soon ignored. But lower levels can show through. Some examples:
This situation might better be described in terms of processes rather than layers, with feedback between the processes.
How can I bare it? My idle, My bridle partner Left me last weak For a made. What a waist Of ours And ours.
When the boundaries between layers are crossed by characters or other textual elements we have 'metalepsis ' - a term first used by Gérard Genette. In Coleman Dowell's novel "Island People" a low level framed story becomes the top level, taking over the narrative, creating a kind of Mobius band.
Sometimes, especially during reading, the concept of layers is ignored; layers are merged together. This is also done in Cartography, in painting (perspective), and in Photoshop (to save storage space). It's often done with a particular aim in mind, fixing from a particular viewpoint. The disadvantage is that the process is irreversable and makes alternative interpretations difficult. During reading some people resist the movement between layers. They become stuck in a layer, trying to read Finnegan's Wake as if it were a poorly spelt straight story. They lose the possibility of seeing how the 2 movements (forwards and backwards; up and down) interact. It's as if an archaeologist ignored the depth artifacts were found in.
We haven't yet mentioned the reader-time component. Within a layer each new element can suggest meanings or eliminate possibilities (for example, consider the effect of each new fact in a whodunit). There can be an association with other phrases in the same layer or with elements in other layers. E.g.
Reading often doesn't proceed linearly through the text. Even in prose there's typically 10% of saccades (eye-movements) backwards. In poetry this percentage is likely to be higher. In particular ambiguity and confusion will provoke backtracking. The amount of backtracking needed will influence the reading strategy. Options include
Chapter-ends and poetic line-breaks tend to force a decision/resolution. The sentence above in the 'layer confusion' section works better with line-breaks
love is a four letter world
Rather than just using the emergent meaning one can have a richer reading experience by retaining the lower-level meaning too, letting it show through, leaving that dimension open for traversal. End-rhymes force an awareness of the lower level of sound, though it's only one of many poetic effects that do this. In general, the path through the text is less linear for the poetry reader than for the prose reader. The following graphs illustrate the idealised differences one might expect to find.
Prose which forces a poetry-like reading strategy might encounter reader-resistance, reminding the reader of the extra dimension.
Hofstadter's strange loops, tangled hierarchies, and hierarchy violation.