Information Technology Reference
In-Depth Information
similar, yet even more flexible patterns of organizing space [129]. They identified
personal territories, group territories and storage territories, which are used for plac-
ing documents that are of little relevance for the current task. These zones are not
clearly delimited; rather they form a continuum with smooth transitions. They can
grow larger and get smaller over time. Storage territories are mobile and move over
the table while the task progresses.
Summing up, spatial arrangements are important for expressing and gaining a
sense of the overall structure, for classifying documents and for referring to other
documents. The question is whether these spatial arrangements are specific for paper
or whether large horizontal displays, so-called interactive tabletops, can provide the
same advantages. Interactive tabletops [98] use the surface of tables as an interactive
display. The screen is typically large enough to display several documents side-by-
side. Direct touch interactions allow users to freely arrange digital documents on
the screen. A limiting factor of most current tabletops is their small resolution. The
XGA or HD resolution, which is typically available, in combination with the large
display size, results in a rather small pixel density. While this is acceptable for im-
ages, text is not readable in a size comparable to that of printed text. The future will
solve this issue. More important are aspects related to the haptic characteristics of
paper. Interweaving of activities, such as flipping through the pages of one document
for skimming and simultaneously writing on another document, is obviously more
difficult without haptic feedback. Terrenghi et al. [151] compared the manipulation
of physical versus digital objects on table surfaces. They found that even if digital
tabletop interfaces copy many of the characteristics of traditional tables, the result-
ing interaction is fundamentally different. With digital tabletops there is little of the
ease with which we manipulate physical objects. For instance, participants required
the double average amount of time for solving a puzzle task with digital objects
than when they used physical objects. Moreover, participants perceived the interac-
tion with physical objects as more convenient. Results of one of our own studies
[146] show that physical documents are used not only on the tabletop surface, but
to a large extent also above or in front of the surface, even when they are used in
conjunction with digital documents. Main reasons are first that documents are held
at an angle which is more comparable for reading than when placed flat on the sur-
face. Second, documents can be easily compared and sorted when they are held in
the user's hands. In summary, large interactive tabletops provide enough space for
flexibly arranging documents; however, current solutions lack the important haptic
aspects of paper.
Mobile Use
A further key affordance of paper is mobile use. Since paper is thin, flexible and
lightweight, pen and paper can be easily taken along and used in a huge variety of
situations and physical places. At least this is true for short documents. If it comes
to carrying several heavy topics or an entire archive, paper is not very mobile, of
course. As a further benefit, pen and paper is always-on, since no battery back must
be charged. Even in environments where only expensive specific computer hardware
