SLAVE TO THE MACHINE: "Surface Tension"

Science revels in the counter-intuitive. For example, take an ordinary glass of water: it's highly likely that some molecules of this water must have passed through Oliver Cromwell. The reasoning has less to do with common sense or intuition than with science and probabilities: basically there are more molecules in one glass of water than there are glasses of water in all the oceans of the world.

Science is full of topsy-turvey, counter-intuitive ideas, such as theories about what electrons actually do inside atoms. They aren't like snooker balls--they live in a strange world of waves and particles and quantum mechanics.

But computing has very different problems with counter-intuition, such as what happens behind a computer's 'GUI', or 'graphical user interface'. This thin curtain stands between a comfortable, metaphorical world and a more counter-intuitive, literal one. It's the space between an ordinary human user and the mysterious code behind the scenes. The interface turns ones and zeros--the very building blocks of all computing--into models and metaphors of things and places. And it turns computing from the mysterious activities of a small élite to the everyday stuff of ordinary people.

But when you 'drag' a document across your desktop to the Wastebasket/Recycle Bin, what's really happening? Do you really drag the file? Are you deleting it? What actually happens is that the PC deletes the file's address from a masterlist. The file itself still exists--it might still be recovered by certain software, until its particular tracks on the disk are finally overwritten by a new file.

But most users have a very different sense of what's happening. Their relationship with the machine is about these virtual surfaces. The metaphors turn a formulaic sphere--DOS-type operating systems, for example--into something far more tangible and tactile. Successful interfaces become so invisible, so subconscious and intuitive that you only notice them when the metaphors break down. For example, the first time you use a Mac, the idea that you eject a floppy disk by 'dragging' it to the wastebasket is incredibly counter-intuitive.

But thanks to the Web, general computer users are also increasingly authors, online publishers and interface designers. Questions of intuitive design pop up as soon as they try to design their first website. Does it have a 'central navigation system' across the site, so visitors don't get lost? At a microscopic level, what are a webpage's 'clickonomics'? What happens when you tweak its links and icons?

Tweaking itself involves a learning process, as you move into these more counter-intuitive terrains. And tweaking makes a lot of science and interface design wondrous, because you realise that intuition isn't fixed. You can collide your existing intuition with the evidence from tweaks and experiments, and actually change and educate it.

Mick Cunningham

Column reproduced from CIRCA 91, , p. 9

A good timeline of the history of GUI interfacs is available here .