Bringing Design to Software
© Addison-Wesley, 1996
Profile 4. Macintosh Human Interface Guidelines
Profile Author: Terry Winograd
The greatest reason for the early success of the Macintosh was the perception by potential buyers that it was easy to use. This perception was not an accident; it was the result of Apple's conscious strategy in creating "the computer for the rest of us."
What was different about Macintosh applications? Most visibly, they were among the first consumer software to make use of the graphic user interface (GUI) that was pioneered by the Xerox Star (Profile 2), with its windows, icons, menus, and pointing device (leading to another commonly used acronym: WIMP). There has been much debate over the benefits and limitations of such interfaces, yet it is clear that, in the large, GUIs enhance usability for many applications, especially for novice users.
Ease of use comes from more than what you see on a single screen. A more subtle, but critical, aspect of the original Macintosh interface was consistency across applications. Applications for different purposes, built by different developers, all followed a common style of providing GUI elements and using those elements to communicate with users. This commonality was the result of a concerted campaign by Apple evangelists, such as Bruce Tognazzini (see Tognazzini, 1992). The job of an evangelist was to convince applications developers to structure their interface in the Macintosh way, rather than in their own way, even if they thought their own way was prettier or better. The evangelists carried their bible, later published as the Human Interface Guidelines (Apple, 1987), illustrated in Figure 4.3.
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Figure 4.3 Macintosh Human Interface Guidelines These guidelines specify how each design element (in this case, a document window) should look, and what behavior it should exhibit. The correspondence of look and behavior is the key to a working design language. (Source: Reprinted by permission from Apple Computer. Human Interface Guidelines: The Apple Desktop Interface. Reading, MA: Addison-Wesley, 1987, p. 43.)
The evangelists' achievement was that any user who was familiar with a few Macintosh applications could approach a new application with a reasonable sense of what it could do and how to make it perform. This sense of familiarity led to the feeling that the Macintosh was easy to use. The guidelines defined a comprehensive design language, as described by Rheinfrank and Evenson in Chapter 4, and were supported by the availability of a programmers' toolbox, which facilitated developers writing programs that followed the guidelines. In many cases, extra programming was required if the developer wanted to violate a guideline.
The Macintosh interface design language included visual and syntactic details, such as the names of standard menu items, and deeper functional elements, such as the use of a clipboard with universal cut, copy, and paste commands to be provided in a standard way in every application. In the early days of the Star, the Lisa (Macintosh's predecessor), and the Macintosh, there was a raging debate about whether the moving and copying of documents, text, and drawings should be done via cut and paste from a clipboard, or via move, copy, and delete, commands, which were dedicated keyboard buttons on the Star. The differences were not just in the names, but also in the underlying conceptual model. The Macintosh designers may have chosen a less functional alternative (there are many people who still argue that they did so), but they did choose, and that choice led to consistency. Every application provided the same clipboard commands, making it possible for users to move text and drawings from one application to the other, regardless of the application. It was many years before this seemingly elementary form of consistency was available in either PC systems or Unix workstations.
A quick browse through Apple's Human Interface Guidelines reveals dozens of language elements, such as the organization of commands into menus; consistent use of dialog boxes for parameters, warnings, and errors; and standard ways of organizing and managing windows. Equivalent style guides now exist for every major interface. It is interesting to see the variations that have emerged from what is fundamentally the same interface, as illustrated in Figure 4.4. The differences are reminiscent of the correspondences among simple corresponding vocabulary words from French, Spanish, and Italian. The common Latin origins lead to a basic similarity, but each language has its own consistency. Also, as is true of natural languages, there is little room for argument about which communicates more effectively. There are minor variations, but, for the most part, what is important is that, within any one language, there is a consistent way of using words that is understood by everyone who speaks that language.
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Figure 4.4 A Cross-Linguistic Comparison Each of the common GUI interfaces has its own variant of the GUI design language, expressed in a style guide. All the widely used interface styles are similar in functionality, and each offers a coordinated set of conventions for representing functions visually. (Source: Reprinted by permission from Aaron Marcus. Graphic Design for Electronic Documents and User Interfaces. New York: ACM/Addison-Wesley, 1992, p. 153.)
In all human languages, rules are made to be brokencreative innovation violates previous conventions. Design languages continue to change and evolve, just as natural languages do. The language of the Macintosh was a replacement for a long-standing and well-known language based on character-terminal interfaces, such as the IBM 3270, for mainframe applications, such as airline reservation and forms entry systems. As Liddle describes in Chapter 2, the designers of new GUI applications had to break loose from the tacit assumptions that had been effective for their design of screen fields, layout, and interaction sequences. The designers of interfaces yet to come will have the same difficulty in breaking away from the WIMP language in which they are now so fluent. The WIMP GUI is not the ultimate user-interface design, any more than Latin was the ultimate language. It has been hardy and useful, but it is tied to the hardware and systems tradeoffs that prevailed in the 1980s.
Lauralee Alben, Jim Faris, and Harry Saddler. Making it Macintosh. interactions 1:1 (January, 1994), 1120.
Apple Computer. Human Interface Guidelines: The Apple Desktop Interface. Reading, MA: Addison-Wesley, 1987.
Apple Computer. Making it Macintosh: The Macintosh Human Interface Guidelines Companion (CD ROM). Cupertino, CA: Apple Computer, 1993.
Aaron Marcus. Graphic Design for Electronic Documents and User Interfaces. New York: ACM/Addison-Wesley, 1992.
Microsoft Corporation, The Windows Interface: Guidelines for Software Design, Microsoft Press, 1995.
Bruce Tognazzini, Tog on Interface, Reading, MA: Addison-Wesley, 1992.