So why do we want to introduce these Communicative Devices? Well, we think that these Communicative Devices are something that pertains to every form of multimodal communication and can explain the role that every element plays when a presentation is generated.
This can allow us, as the system designers, to generate a presentation knowing exactly why we made any temporal, spatial, and/or stylistic decision.
The goal of the devices is to
What are they? Communicative Devices are a set of rules that if you are generating a presentation, they suggest how, where, when, and why you put elements into the presentation. If you are examining a presentation, they describe the communicative function of every element in the presentation. So, they are not attributes of an element, but describe the relation of any element to every other element in a presentation.
For example, one of these communicative devices is cohesion. An example of cohesion can be seen in this html document. We are using the same font and colour for every H2 element to create cohesion across the headings in the document. Cohesion can occur across a number of different elements, pages and a website as a whole.
Cohesion can also work over time. For example, in the current chiaroscuro presentation the labels that are grouped with the image break cohesion by not staying in the same place over time. The labels also disrupt temporal cohesion by not fading in and out with the images.
Formal Definition: Communicative Devices are the formal structures - the grammar and syntax - of multimodal hypermedia communication.
Comment by Stefano:
This concept of CD is independent from the context of the presentation, and infact these CD are more related to the way human beings perceive things (i.e. they look for similarities, symmetry, hierarchy, ordering in a document).
It is interesting to notice that while for ex. ordering is a common concept to human beings, different cultures might implement it differently, like left-right (western cultures) or right-left (eastern cultures). The rule ordering or hierarchy still holds, its implementation can change.
I also think these CD relate pretty well to the bookshelf CD because the latter is an implementation of several CD as presented in this document: the bookshelf might enforce Integration in requiring a certain symmetry while displaying objects, or implements a certain Rhythm of the presentation due to the padding between objects, or Framing giving all related objects "a place to be" (Integration, Rhythm and Framing are some of Marcos' CD's).
/Comment by Stefano.