Scroll direction, touch screens, trackpads

When we interact with a touch screen, we expect a certain “directness”; that is, if I grab something and push up, I expect that thing to move up.  Like dragging a web page up or down.  However, did you ever notice that on a track pad (like on a laptop), the direction is reversed?

  • Trackpad:  fingers move DOWN, position indicator goes DOWN, web page goes UP
  • Touchscreen:  fingers move DOWN on surface, position indicator (on far right) goes UP, web page goes DOWN

It’s so subtle, perhaps you’ve never noticed it so I made a video:

I sometimes use this inconsistency (position indicator goes down, fingers go down, but screen moves up) in my class as an example of a violation of an old display design guideline called the principle of the moving part.  It suggests that when you have an indicator on a display, it should move in the same direction as the thing it’s indicating.  The touchscreen/trackpad issue is more complicated because you also have an input incompatibility (fingers and display moving in opposition).

The difference between the touchscreen and trackpad is in what the fingers are “controlling”: the screen or the position indicator?

Am I obsessing over a trivial issue?  Probably; this is something that you just get used to.  But I seem to not be alone in noticing this issue.  Apple, in their next version of their operating system, will make trackpad navigation consistent with touchscreen navigation (fingers move DOWN on surface, position indicator (on far right) goes UP, web page goes DOWN).  Fortunately for some users, it is a user-selectable feature:


5 thoughts on “Scroll direction, touch screens, trackpads”

  1. I would find this more informative if it included a discussion of the distinctions between a touch screen interface and a window on a desktop. Namely, the scrollbar. I agree with the principle mentioned, but moving fingers on a trackpad isn’t really moving the screen, it is moving the scrollbar. If you click and drag a scrollbar with a mouse, the mouse moves down, screen moves up. Same with fingers moving the scrollbar. If you reverse this, it would obey the principle, but would be opposite your expectation based on years of using a mouse. On a touchscreen, you are not controlling the scrollbar, you are controlling the screen, although the scrollbar is often shown as a derived visual reference of document position. I’m not saying we should rely on mouse habits forever, but the current system is not completely counter intuitive.

  2. Good post. This is a topic I’ve thought quite a bit about (working at Synaptics where we make touchpads)…

    As you say, on direct-touch touchscreens there’s an inherent metaphor that you’re grasping and moving the content directly, whereas on indirect-touch touchpads the metaphor is more like you’re moving a viewport or the scrollbar. Those seem like the most natural metaphors for most users, at least up until recently.

    I think several factors are causing the change: people are getting more used to direct-touch interfaces, OS’s are becoming more about manipulating content rather than windows (as Apple is clearly doing), and touchpads are getting larger and richer with gestures.

    It’s interesting that Apple’s new option for this controls both the scrolling and the swiping direction. I’m guessing that the option for swiping is more important for users, but once they decided to offer that option then it became apparent that scrolling needed the option also.

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