This article is unfinished - you have been warned!
The mouse hover behaviour has long been a favorite of interface designers. It allows for definitions and explanations to take up zero screen real estate until actually needed. For screen elements to take on a reactive, often almost ‘eager’ personality. And of course, for things on a screen to look and behave like (at least some rendition of) things from the meatspace.
Naturally, the hover state can easily be misused. Vincent Flanders coined ‘mystery meat navigation’ as a term for a site’s menu which is rendered frustratingly opaque through a lack of meaningful labels. In a fundamentally utilitarian situation this is a blatant design sin. However, I would cautiously counter that some judicial use of mystery meat is fine, as long as it is applied to non-primary elements and for a good reason. Or in a project where utilitarian function is not the primary goal. That’s a whole other discussion though.
In recent research on application iconography, I came across many anecdotal examples of people cursing a change in a simple ‘save’ icon and lamenting the impossibility of tooltips in touchscreen interfaces. One of note is of an iPad Gmail user having to load up the same site on their PC in order to decipher the opaque meaning of the freshly updated button icons. Mouse hover as saviour.
Keystrokes have always been discrete. Continuous motion is possible but only in a discrete direction. Curves are not a keyboard’s strong suit. The motion of the mouse however, by its very nature, translates the intensely non-discrete nature of our
meatspace digits, twitches and proprioception into a beautiful arc across the disparate binaries of the digital interface.
By replacing the mouse with a trackpad, stylus or finger, we arguably also remove the sense of place within the screen, the feeling of persistent presence. With this goes the perpetual, (unnecessary?) space between destinations.
Which is great. We can close the gap as fast as we can move our hand, rely more on our natural proprioception and settle into Fitt’s Law a little more. We still have drag-and-drop, swipe, pinch and multi-touch to retain some affordance, allowing these interfaces to be at least as easy to grok as our aging mouse-driven ones.