In response to my recent interactive essay about interactions, Waider on Mastodon posted a great crystallization of a common problem:

There is nothing quite so frustrating as a persistent user interface papercut. You know it’s there, but you keep running into it because the moment you start thinking about what you’re doing instead of how you’re doing it, that knowledge slides away until BAM you run into it again.

I think this is really nicely put and highlights about why it’s very important to care about this kind of stuff.

If you forgo a standard interaction out of carelessness, a bug, bad systems thinking, or for other reasons, you’re not just making your users frustrated by something not working. You’re also at risk of making them frustrated at themselves, assuming they can change what their fingers do easily, not fully knowing that a) this is motor memory, not just regular conscious actions (and any memory is hard to “update” intentionally), and b) motor memory is separated from regular, declarative memory, and not possible to reason with using the same techniques.

(As an example, it’s very hard when keyboard shortcuts or mouse gestures disagree between apps, because while you consciously might know which app you’re in, that’s not necessarily true of your fingers.)

Waider continues with an example:

The canonical example of this, for me, is Microsoft apps on macOS: even now, decades after Microsoft started producing macOS versions of their apps, they insist on largely disregarding the native UI idioms in favour of their own. Current pet hate is that if I’m commenting on a document, the Ctrl-A/Ctrl-E actions do not work, and boy howdy do I use those constantly.

My recent example is that even though I wrote about Safari overriding the natural “scroll to top/bottom” tap gesture on their tabs – so I am aware of it in my declarative memory, I know Safari designers messed it up, and I know exactly what to do and not do – my fingers still occasionally tap to scroll in Safari anyway.