The electronic book

The result of integrating classical book structure, or rather the familiar concept of a book, with features which can be provided within an electronic environment, is referred to as an electronic book, which is interpreted as an interactive document which can be composed and read on a computer. From the conceptual side, it is an attempt to overcome the limitations of paper books by adding a series of useful features which are made possible through the nature of an electronic environment. The main features of electronic books are that they are dynamic, reactive and can be made available in different formats and/or editions in a short time. For this reason the translation from paper to electronic environment is not appropriate for every type of publication and for every type of reader; the process of reading and the tasks readers are attempting to complete have a central role in judging the suitability of this translation.

In addition, the cognitive overhead which results from the special environment chosen (i.e. the computer) represents a valid reason for carefully considering the appropriateness and the method of realizing this conversion. The fact that technology is able to represent documents on the screen is not a sufficient reason for translating every piece of paper into electronic format. It is important to consider the subject-matter and usage of the specific paper book in order to decide whether an electronic version will be useful or not. Observations of the behavior of the market for paper and electronic publications show that currently only a very small percentage of paper publications (up to a maximum of 10 per cent for extremely successful productions, such as encyclopedias and dictionaries) are sold in electronic format, and that users prefer to keep a paper version in addition to the electronic one (Saur, 1996; Pope, 1999).

For this purpose it is important to define different kinds of use corresponding to different types of document. These range from ancient manuscripts to modern examples of hyper-literature such as Afternoon (http://www.duke. edu/∼mshumate/mjoyce.html) by M. Joyce (http://sirrus.broder.com/affiliates/manho.html), a HyperCard stack by Manhole, which tells a children’s tale through pictures and invisible links. From the technological point of view electronic books need powerful processors, large amounts of storage and the capability of managing combinations of different types of data. It is the same kind of difference observable between a classic typewriter and a normal word processor which work with a static and a dynamic version of a document respectively.

4.1. The metaphor of the paper book applied to the electronic book

The metaphor is a rhetorical tool which provides a valid means for expressing difficult concepts by referring to simpler objects which have the same qualities. Introducing metaphors to computer system design and teaching presents opportunities to play an important role in augmenting people’s familiarity with the computer world. For this reason it is important to investigate more deeply the role and meaning a metaphor could assume in a specific field such as computer systems. Different experiences and choices can be found in this area from which it is possible to extract some guidelines for using metaphors while avoiding the risk of confusing the user with poor or inappropriate choices.

Two main aspects of the metaphor are its scope and its level of description. The first attribute defines how broad should be the range of objects belonging to the system reproduced by a metaphorical substitute. The second dimension suggests the existence of different levels of description when working with metaphors. For example, it is possible to distinguish between: activity metaphors, mode of interaction metaphors, and task domain metaphors. The first type supports users in expressing their intentions at a high level, the second suggests a model for user-computer communication, while the third helps users to understand the task being supported by the system.

One of the possible approaches for designing an electronic book is to follow the traditional book metaphor. This is intended to be an activity, mode of interaction, and task domain metaphor. Books are well-known repositories for information. Their structure has historical and functional value and this structure invokes a way to read and consult them that is familiar to readers. By maintaining the same model on screen, people’s access to electronic information can be facilitated. Readers can be presented with an electronic representation of books which can be browsed and used in a similar way to the original paper version.

This particular approach helps to overcome some of the limitations inherent in an electronic environment, such as the loss of the physical aspects of the book, e.g. its thickness, which can be used as orientation clues. Evaluations of the use of the book metaphor have proved that it represents a suitable basis for building good interfaces for a variety of electronic books (Barker et al., 1994). Nevertheless, there is another set of problems which are related to technological shortcomings, mainly the limited screen size and resolution, that makes reading an electronic book less pleasant than a paper book. The next section will discuss the results of experiments into the legibility of screen-based textual information. These results have played an important role in the design and implementation of the visual book.

4.2. Book legibility

One of the main problems encountered in designing an electronic book is concerned with its legibility (McDonald, 1994). Readers are used to reading from paper with well-defined features, such as page and character dimensions, the ratio between words and spaces, the contrast between characters and the white page, and many other typographical elements (Burt, 1959). Typography and good legibility are strongly related and it is held that “Comfortable legibility is an absolute benchmark for all typography” (Tschichold, 1991).

The transition from paper books to electronic books presents a set of problems which are specifically related to typographical features. In particular the attempt to maintain the same ratio between written text and white space requires the use of large screens (21 inches or more). The need to reproduce exactly the same character appearance requires a flexible text processing environment which can support the construction and use of new sets of symbols. Finally, screen resolution remains a heavy limitation which only technology can overcome.

Many experiments (Gould et al., 1987a; 1987b) have been conducted in order to establish the effective difference between reading from paper instead of reading from screen, even if it has not always been possible to identify which screen features were responsible for the difference. A possible reason for this is that different variables can interact to create this situation and, as there are so many parameters which contribute to the reading process, it is difficult to distinguish between them and to repeat the experiment with the same parameters. Technology is also important in determining display features as it can modify meaningfully the results of this type of experiment (Black and Boag, 1992).

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