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The Anti-Mac: Violating the Macintosh Human Interface Guidelines

CHI'95 Controversial Encounter:
Moderator: Stuart Card, Xerox PARC
Anti-Mac Team: Don Gentner and Jakob Nielsen, SunSoft
Defenders: Austin Henderson and Don Norman, Apple Computer

Note: This abstract summarizes the Anti-Mac position and was written by Gentner and Nielsen based on their Anti-Mac project. The debate at the conference will include opposing views.

© ACM

Abstract of the anti-mac position:

Graphical computer interfaces have become the norm. They are based on a number of principles such as metaphor, see-and-point, direct manipulation, user control, and WYSIWIG. The Anti-Mac project explored alternative interfaces that might result from violating the principles behind conventional graphical interfaces. What emerges is a human-computer interface based on language, a richer representation of objects, expert users, skilled agents, and shared control.

Keywords:

Computer-human interface, Macintosh human interface, metaphor, direct manipulation, user control, WYSIWYG, user interface design, WIMP interface, language, computer agents, objects, attributes, futurism.

Beyond Macintosh

Physicists and mathematicians often stretch their imagination by considering what the world would be like if some of their basic assumptions and principles were violated (for example, see [1]). This has led to new concepts such as non-Euclidean geometry, positrons, anti-matter, and anti-gravity. At the least, violating basic assumptions is a useful mental exercise, but a surprising number of the resulting concepts have ended up as useful descriptions of the real world.

In the Anti-Mac project, Gentner and Nielsen explored the types of interfaces that could result if we violated each of the Macintosh human interface design principles. The primary reason for focusing on the principles behind the Macintosh interface is that the Macintosh is commonly thought to be a good example of the current interface paradigm and Apple Computer has published an explicit list of Macintosh human interface design principles [2]. These principles have not significantly changed since the introduction of the Macintosh; style guides for other popular graphical interfaces, such as Motif, OPEN LOOK, and Windows, list a very similar set of principles as the basis for their interfaces.

We should state at the outset that we are devoted fans of the Macintosh human interface and frequent users of Macintosh computers. Our purpose is not to argue that the Macintosh human interface guidelines are bad principles, but rather to explore alternative approaches to computer interfaces. The Anti-Mac interface is not intended to be hostile to the Mac, only different. In fact, human interface designers at Apple and elsewhere have already incorporated some of the Anti-Mac features into the Macintosh desktop and applications. The Macintosh was designed to be "the computer for the rest of us" and succeeded well enough that it became "the first personal computer good enough to be criticized" as Alan Kay once said. The Anti-Mac project should be taken in the same spirit.

The Macintosh human interface design principles

According to Macintosh Human Interface Guidelines [2], the design of human interfaces for Macintosh system software and applications is based on a number of basic principles of human-computer interaction. These principles are: metaphors, direct manipulation, see-and-point, consistency, WYSIWYG, user control, feedback and dialog, forgiveness, perceived stability, aesthetic integrity, and modelessness. These principles have led to excellent graphical interfaces, but we wished to ask two questions. First, how do these principles limit the computer-human interface? Second, what types of interfaces would result from violating these principles?

The Anti-Mac interface

Just as the Macintosh design principles are interrelated and give a resulting coherence to the Macintosh interface, violation of those principles also points to a coherent interface design that we call the Anti-Mac interface. The basic principles of the Anti-Mac interface are: a) a richer internal representation of objects, b) a more expressive interface, c) expert users, d) skilled agents, e) the central role of language, and f) mixed locus of control. It probably should be admitted here that although we attempted to violate all of the Macintosh human interface design principles for the Anti-Mac interface, in the case of forgiveness and aesthetic integrity we had to be content with merely reinterpreting the existing principles.

For a document, a richer representation could include its authors, topic matter, keywords, importance, whether there are other copies, what other documents it is related to, and so forth. The list of attributes is similar to those that would be needed by a good secretary who was expected to handle the documents intelligently. It is not necessary for the secretary to fully understand the document contents, but they must have a general sense of what it is about and its significance. Richer representation of objects will allow more intelligent interpretation of user commands, but it will also be reflected in a more expressive interface. Notice on a bookshelf how books have an endless variety of appearances and yet are all recognizable as books. This variety adds visual interest and helps us quickly locate a particular book. We should think about the trade-offs between ease of learning and power in computer-human interfaces. If there were a compensating return in increased power, it would not be unreasonable to expect a person to spend several years learning to communicate with computers, just as we now expect children to spend twenty years mastering their native language. Language lets us refer to things that are not immediately present, reason about potential actions, and use conditionals and other concepts that are not available with a see-and-point interface. Another important property of language missing in graphical interfaces is the ability to encapsulate complex groups of objects or actions and refer to them with a single name. Finally, natural languages can cope with ambiguity and fuzzy categories.

Conclusions

The following table compares some of the characteristics of the original Macintosh and Anti-Mac user interfaces:

Bruce Tognazzini's "Starfire" film [3] was a recent attempt to show how a high-end workstation might look in the year 2004. The interface visualized in the film has several similarities to our Anti-Mac design. Despite its Anti-Mac aspects, Starfire is still a very recognizable computer with many similarities to current user interfaces and research systems. Indeed, it should be since it will not be realistic to assume anything else to be able to reach the market in only ten years. Conversely, we can even argue that there are some Anti-Mac features in evidence in current commercial products. For example, products like On Location and SearchIt show autonomy in taking the initiative to index the user's file system when needed and allow users to retrieve email objects by content and other rich attributes even though each email message may be part of a large text file when viewed through the standard system interface.

To realize the full benefits from the Anti-Mac approach we would argue that it will not be sufficient to retrofit its features one at a time to systems that basically follow current user interface architectures. We believe that an integrated design that builds a new user interface from the bottom up will be more coherent and will have a better potential for increasing user productivity by at least an order of magnitude. A full Anti-Mac system will likely have to be based on deep object structures in an architecture that supports network-distributed objects and detailed attributes that are sufficiently standardized to be shared among multiple functionality modules. Realistically speaking, such a complete redesign will take some time to appear. Even if the full system were not to appear for several years to come, it is necessary for detailed research to begin now to develop the needed features and to collect usability data as to how the Anti-Mac characteristics should be shaped to truly meet users' needs.

References

1. Alfven, H. Worlds-Antiworlds. W. H. Freeman, San Francisco, 1966.
2. Apple Computer. Macintosh Human Interface Guidelines. Addison-Wesley, Reading, MA, 1992.
3. Tognazzini, B. "The ‘Starfire' video prototype project: A case history." In Proceedings ACM CHI'94 Conference Human Factors in Computing Systems (Boston, MA, 24-28 April 1994), 99- 105.