Mixed Metaphors, Dead Metaphors and Magical Metaphor Elements

· Metaphors may become “dead”. In this case the mapping from the source domain is lost. The original metaphor becomes an integral part of the target domain. The English examples above are all dead metaphors.

· For the most part the Desktop metaphor is dead (but see later about the trashcan).

· Mixed metaphors occur when more than one source domain is mapped to a single target domain.

· A simple metaphor cannot me usefully mapped to an OS. Therefore HCI is rife with mixed metaphors.

· Example: In most OS GUIs we have “desktop” elements (folders, files, trashcan for deleting, etc), “menu” elements, elements from a “printing” domain (copy/paste), and elements from a “mechanical” domain (buttons). There are many source domains.

· However this does not seem ever to have been a problem. Besides which all these elements are essentially dead.

· [Rohrer] describes an interesting feature of HCI metaphors – Magical metaphor elements

· A magical metaphor element is one which takes on certain “magical properties”

· For example spreadsheets can automatically calculate sums of columns as you enter numbers. This is an example of “sympathetic” magic.

· The most notorious example of “unsympathetic” or baffling magic is the notorious Mac Trashcan. Here the “magic” lies in the fact that to eject a floppy disk you drag the disk icon onto the Trashcan icon.

· Why is the trashcan example so completely counter-intuitive? I can remember my own feelings when encountering the trashcan idiom for the first time – complete astonishment.

· [Rohrer] suggests that this is linked to natural human intuition – a false positive is safer than a false negative.

· The conclusion of this is that metaphoric interface design must take human intuition into account. Users gut feelings must be respected.

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