Usually, Rands doesn’t post very frequently, but each time he does publish an article, it’s always a treat. Among other things, he is very good at analysing behaviour in general, and nerd behaviour in particular (see the seminal The Nerd Handbook, which is the way I was introduced to Rands’ writing back in 2007).

I was eager to know what were his thoughts about Mac OS X Lion’s interface, and I frankly did not expect a specific post about it, much less two posts. Yet, to my surprise, between July 29 and July 31 he posted The Desktop Transition and The One Rule, both highly recommended reading.

Rands has managed to convince me that Mission Control may be more effective than the previous combination of Exposé and Spaces. The only point I’m still unconvinced about and upon which I don’t agree with him is (you guessed right) when he talks about the new, ‘natural’ scrolling direction in Lion:

For those of you not familiar with the situation, in the latest release of Mac OS X, Apple reversed the scrolling action. Your scrolling wheel or your two-finger trackpad drag go in the opposite direction. Cruel joke, right? Did they swap the left and the right buttons on the mouse, too?

For an action I perform hundreds of times a day, I’m shocked that I’ve left natural scrolling on and now that I’ve become used to it, I’ll explain why old scrolling is actually wrong. That’s right. We’ve all been doing it wrong because it’s not how we think.

Try this. Go grab your closest iPhone or iPad, turn it on, and scroll… in any direction. Do it a couple of times, have some fun. Now stop. Before your next scroll, I want you to think what your brain would do if when you put your finger on the screen and slid to the right if the screen went to the left. Usability disaster, right? No way I’d ever convince you that was the right way because you would argue “that is the natural way for it to work”.

I agree.

It’s called natural scrolling because the scrolling works how your brain expects. I know this because each time I’ve scrolled and thought, “Whu…?” I remind myself: “Think as if your finger was on the screen” and then I’m content.

In usability terms, if you have to resort to thinking to correctly execute an action, something’s not exactly right. I’ve already expressed my thoughts regarding this particular gesture in Lion, but I’ll say that again: there isn’t a right or wrong way of scrolling. There are two different interfaces: in one you manipulate objects by directly interacting with them on the screen with multi-touch gestures. In the other you manipulate what’s on screen indirectly. No matter how intuitively (see Magic Trackpad): unless Apple starts introducing Macs with multi-touch displays, their interfaces will always be operated indirectly.

Gesturing on a trackpad seems a rather acceptable compromise to interact more directly with interface elements on a Mac, but there’s always some kind of abstraction involved: to scroll ‘naturally’ on a Mac you have to think as if the text you’re scrolling were on your trackpad or, as Rands puts it, as if your finger were on the screen. Put this way, this isn’t much different from the kind of abstraction that there is behind the scrolling on the classic Mac OS up to Snow Leopard — i.e. the reason why you scroll down to move text up is that you’re not operating on the text itself, but you’re grabbing the scrollbar and using it to move the text for you, so to speak.

This, up to now, has been considered an effective abstraction to scroll text on a mediate interface: you operated the scrollbar as a slider, as a counter-weight, so you scrolled in the direction you wanted the scrollbar/slider to go. With Lion, you have to change your target (not the scrollbar anymore, but the text) and think like you’re using another interface, iOS’s. I still question the effectiveness of this shift, since not everyone on a Mac uses the same input device (there are mice, trackpads, even graphic tablets), while everyone with an iDevice uses their fingers.