The white space around a poem is the silence that surrounds the sound of the lines of that poem. It can be used as a contemplative space where you begin to analyze and dissect the poem's meaning. It is like the space around a sculpture in that same way. It is the area that becomes your surroundings and therefore begins your relationship with it. You become part of that space and so part of that particular work.
Presentation is a first glance at a subject manner.
Representation is a replica, a reflection of that subject manner. It is a second hand account. A presentation of the subject in its pure from that is true to itself. A representation can take on a different form or perspective giving new light or different meaning. Cognition is how you or the artist sees and values a work.