[titzer]

> it requires active attention to operate.

It just requires context. How that context is critically important. If it is a hierarchical menu, then the context is the navigation path (i.e. the sequence of previous button pushes, each of which transitions from one state to the next). Importantly, with a fixed hierarchical menu, the path to a button's functionality doesn't change and can be memorized. With some audio feedback, the current state can also be announced, so that a person's mental state matches the state the interface is in.

There are several problems with touchscreens, not the least of which is the context issue. The next issue is there is no tactile feedback, which requires you to look at where you are touching, often because interactive things can appear anywhere.

[andrewla]

Doesn't this assume that you're advancing a state machine from some known initial state? If you are in the middle of a navigation and you are interrupted, in order to figure out what to do next you need to recover context. The more your muscle memory remembers the sequence ( 1 -> 2 -> 2 -> 3/4 for raising/lowering the fan speed ) the less you'll be able to access it consciously and the more you'll have to look at the options to figure out what to do.

The lack of tactile feedback on touchscreens is an issue when using it, but I'm not convinced that it's any better or worse for partial-attention tasks. For full attention tasks (e.g. navigating a settings menu) it's far superior to a button-based approach.