Google > Material Design > What is material? > Objects in 3D space:
Dynamic elevation offsets are the goal elevation for the component to move towards, relative to the componentâ€™s resting state. They also ensure that elevation changes are consistent across actions and component types. For example, all components that lift on press have the same elevation change relative to their resting elevation, and toolbars that lift to allow material to slide under them have consistent offsets.
I’m trying to get a good grasp of Google’s Material Design user experience language, but there’s a few quirkiness. Here’s one: “lift on press.” That sounds counter intuitive. I press a button and it lifts? Hmm. Shouldn’t it be the other way around? I press a button and it depresses. Doesn’t that make more sense? More intuitive? Press something, and it goes in.
Update: Under Animation > Responsive interaction in the Lift on touch section:
When a card or separable element is activated, the card should lift to indicate an active state.
This makes sense: I am trying to press, hold on to, and move around the card. The lifting of the card to show that I’ve got it is intuitive. Which is quite different than pressing a button: when I press a button it should not come out, but go in.