Information Technology Reference
In-Depth Information
3.5 Model of Information
A model of Pen-and-Paper User Interfaces should not only cover paper-based inter-
actions, but also address how information is distributed between physical and digital
representations. We distinguish two orthogonal principles that model the relations
between printed and digital pieces of information on a semantic level: equivalence
and complementarity. Our model draws inspiration from research on multimodality
that formalizes the relationships between different modalities [19, 160].
Equivalence of Information
We refer to the first principle as equivalence. It is
illustrated in Figure 3.9 (left). This principle captures that the same piece of infor-
mation can be transformed between equivalent representations on different media.
The user can choose the representation which best fits her needs. As a matter of
course, this is only possible if the piece of information disposes of an equivalent
representation. For instance, a video document does not have an equivalent physi-
cal representation.
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In contrast, a book, a printed article, or a PDF document have
equivalent representations. Their contents can be transformed to a spatially fix, tem-
porally static and two-dimensional layout that can be either displayed on a screen or
printed on paper. No essential contents are lost and an unambiguous mapping from
the printed to the corresponding digital contents is possible.
On the level of information, both representations are equivalent, as they con-
tain the same contents. However, different representations can offer different affor-
dances. For example, the user could utilize a printer to transform a digital represen-
tation to a printed one because it is more convenient to read and annotate informa-
tion on paper. In the reverse direction, the user could transform a printed piece of
information to an equivalent digital representation that better affords searching for
specific terms.
Two or more equivalent representations of the same piece of information can
be used one after another, or they can be used in combination at the same point
of time. The latter combines the affordances of several representational media. For
example the printed representation of a document can be used to quickly navigate
between different pages of this document, while the digital representation better
affords editing, moving or deleting existing annotations, as it is updated in real-time.
Complementarity of Information
The second principle, called complementarity,
models the orthogonal dimension. It is illustrated in Figure 3.9 (right). The infor-
mation space consists of several, different pieces of information that are distributed
across different representations and complement each other. Each piece of informa-
tion is available in one fix representation. The distinctive features of both principles
are shown in a matrix in Figure 3.10. In practice, both dimensions appear together.
For example, one of the complementing pieces of information can in turn be trans-
formed to an equivalent representation.
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Also a video document can actually be represented on paper (e.g. as a token containing only the
tile or as a collection of printed key frames). However, this representation is significantly different
from how a video is represented in a digital representation.
