Visual metaphor

The ambitious graphic designs of the Xerox Star/Alto and Apple Lisa/Macintosh were the first mass-market visual interfaces. They were marketed to office professionals, making the 'cover story' that they resembled an office desktop a convenient explanatory device. Of course, as was frequently noted at the time, these interfaces behaved nothing like a real desktop. The mnemonic symbol for file deletion (a wastebasket) was ridiculous if interpreted as an object placed on a desk. And nobody could explain why the desk had windows in it (the name was derived from the 'clipping window' of the graphics architecture used to implement them - it was at some later point that they began to be explained as resembling sheets of paper on a desk). There were immediate complaints from luminaries such as Alan Kay and Ted Nelson that strict analogical correspondence to physical objects would become obstructive rather than instructive. Nevertheless, for many years the marketing story behind the desktop metaphor was taken seriously, despite the fact that all attempts to improve the Macintosh design with more elaborate visual analogies, as in General Magic and Microsoft Bob, subsequently failed.

The 'desktop' can be far more profitably analysed (and extended) by understanding the representational conventions that it uses. The size and position of icons and windows on the desktop has no meaning, they are not connected, and there is no visual perspective, so it is neither a map, graph nor picture. The real value is the extent to which it allows secondary notation, with the user creating her own meaning by arranging items as she wishes. Window borders separate areas of the screen into different pictorial, text or symbolic contexts as in the typographic page design of a textbook or magazine. Icons use a large variety of conventions to indicate symbolic correspondence to software operations and/or company brands, but they are only occasionally or incidentally organised into more complex semiotic structures.

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Figure 5.24: Apple marketed the visual metaphor in 1983 as a key benefit of the Lisa computer. This advertisement said 'You can work with Lisa the same familiar way you work at your desk'. However a controlled study by Carroll and Mazur (1986) found that the claim for immediately familiar operation may have been exaggerated.

Copyright © Apple Computer, Inc and Computer History Museum, Mountain View, CA. All Rights Reserved. Reproduced with permission. See section "Exceptions" in the copyright terms below. Download or view full resolution (891 x 617 pixels. 50 KB)

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Figure 5.25: The Xerox Alto and Apple Lisa, early products in which bitmapped displays allowed pictorial icons to be used as mnemonic cues within the 'desktop metaphor'

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Figure 5.26: Apple Lisa.

Courtesy of Mschlindwein. Copyright: CC-Att-SA (Creative Commons Attribution-ShareAlike 3.0 Unported). Download or view full resolution (558 x 646 pixels. 99 KB)

Summary

Theories of visual representation, rather than theories of visual metaphor, are the best approach to explaining the conventional Macintosh/Windows 'desktop'. There is huge room for improvement.
Where to learn more:

Blackwell, Alan (2006): The reification of metaphor as a design tool. In ACM Transactions on Computer-Human Interaction, 13 (4) pp. 490-530

“ Despite causing many debates in human-computer interaction (HCI), the term "metaphor" remains a central element of design practice. This article investigates the history of ideas behind user-interface (UI) metaphor, not only technical developments, but also less familiar perspectives from education, philosophy, and the sociology of science. The historical analysis is complemented by a study of attitudes toward metaphor among HCI researchers 30 years later. Working from these two streams of evidence, we find new insights into the way that theories in HCI are related to interface design, and offer recommendations regarding approaches to future UI design research. ”

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