If I had to advocate for just one aesthetic (which is silly on its face), I suppose restrained skeuomorphism would be the one.
I've got to say, I don't understand why people keep mentioning drop shadows, though. Drop shadows seem fairly uncommon. Even Google only uses them for mouseover.
And mouseover is, in my opinion, too late to indicate what's clickable and what isn't. It's a nice confirmation, but the user should already know before they even move their mouse. If you've got a user aimlessly moving their mouse over things trying to determine what's clickable, you've failed at design.
Put your cursor in the search field. More shadowy goodness there. Click on your avatar in the upper right, the popover has a prominent (too prominent IMO) drop shadow. It's everywhere.
As to mouseover, I agree it's for confirmation. But if we need to confirm functionality with drop shadows and gradients - what message does that send about usability?
One thought is that perhaps we should have the drop shadows and gradients there to begin with.
I should have been clearer. I was referring to drop shadows on buttons.
I have to say, though, I think the search box picking up a drop shadow is the perfect example of gratuitous affordance. Putting the focus on the search box turns the border blue. Does anyone actually need the drop shadow? Alternatively, if users need the drop shadow, do they need the blue border. Do they need either one, given that the cursor appears?
> As to mouseover, I agree it's for confirmation. But if we need to confirm functionality with drop shadows and gradients - what message does that send about usability?
Tells me that they aren't really needed in the first place. And given the increasing prevalence of touch devices, I'd say that making your UI clear without resorting to mouseover effects has become a requirement.
> One thought is that perhaps we should have the drop shadows and gradients there to begin with.
If they were there to start with, the designers would no doubt have added some other hover indicator. People have grown to expect hover changes (especially with web UIs), and indeed UIs seem awkward without them. However they should still not be necessary to indicate that something is clickable.
I agree with this so hard I think I hurt my back.
From Wikipedia: a skeuomorph is "an element of design or structure that serves little or no purpose in the artifact fashioned from the new material, but was essential to the object made from the original material"
The gradient and shadow on buttons are not just ornamental, they serve the purpose of conveying depth, and consequently that they afford being pushed (also, real-world buttons are usually a solid color).
The reason why I use the term skeuomorphic in this context is because there are those who believe that what you and I believe is affordance is actually superfluous and ornamental.
What else is flatland design if not a complete rejection of the value of drop shadows and gradients as affordance?
