Moving windows has always felt a bit odd on an unconscious level. You are moving a very stiff, pretty sizable thing, according to our eyes, but yet the effort on the mouse is no different than moving just the tiny pointer. On some systems, the shadow around each window makes it look even heavier since it makes us perceive it as something thicker than a sheet of paper. If you moved a perfectly rigid 20x25cm flat material that was 5mm thick, which is about what one of my browser windows looks like, it would have some inertia and air resistance to it, yet I feel no difference in my hand. I can easily feel it when moving a physical sheet of paper around in the physical world, yes this visably more massive sheet of paper on my screen has zero weight, inertia or air resistance.

The perception of touch in our hands is strongly tied to our visual perceptions of the things we see in our hands. When these two perceptions don’t match up, there is a feeling of numbness, perhaps unconscious but present nonetheless. At this point, we are so used to this feeling that we don’t really ever think about it.

I recently upgraded to Ubuntu Hardy, which has some Compiz effects enabled by default. Compiz is software that allows a wide range of visual manipulations of all sorts of elements of the GUI. The most common one is the “rubber” windows. Basically, it makes the normally stiff window into a rubbery thing. When I first saw this, I thought it was very nifty, but merely eye candy that I would shortly turn off once the effect became annoying. I was very much surprised to discover that instead of it becoming annoying, it was the stiff windows that bothered me. I started to find the errant few windows that were not rubbery where the annoying ones.

I think there is a similar thing going on with sound design for computers. When computers got sound, both Windows and Mac OS X were plastered with interface sounds. Almost everyone found them really annoying and quickly turned them off. So they were mostly removed as a default thing. But some sounds have crept back in. Like the mail-sending and trash-emptying sounds in Mac OS X. When such effects are carefully considered and used judiciously, they are actually quite useful.