from Hacker News

Visualizing Fitts's Law (2007)

by kevin on 3/18/18, 7:51 PM with 35 comments

  • by oneplane on 3/18/18, 12:10 PM

    IIRC this is one of the reasons the UI on the Mac opted for a fixed context-dependant menu bar at the top of the screen instead of the per-window one used by Windows (and Java).

    It's basically 'fling your pointing device at the top' and 'go left or right to get the button you want'. Due to the lack of borders/stops, this would be harder if it was sandwiched between a titlebar and window content.

  • by kurthr on 3/18/18, 3:30 PM

    The engineers way of thinking about Fitt's Law is as a human control system. We motion control our hands by using feedback (visual, tactile, proprioceptive). The servo time response to a step function (new location to click) of that feedback loop depends on the required accuracy and allowed overshoot. The larger the target, the higher a velocity/acceleration you can use to hit it without missing. You learn very quickly that large objects (like edge of screen) allow much more gross movements than single pixel target... and the farther you have to go the larger the time at a given tracking velocity.

    What is at least as interesting is the cognitive load of tracking/pointing, clicking/chording . Mental load and apparent time appear to be the reason why typing can be slower than a menu system, but it feels faster. Similarly, people will report a feeling like a trackpoint (IBM keyboard nipple) takes longer than a mouse even when they're actually faster in hitting targets. Presumably, this is because they have to track the cursor to know velocity and position, while a mouse or touchpad uses your body's knowledge of hand position/velocity that is missing from a force based input.

    What you're used to feels right in any case.

  • by ProxCoques on 3/18/18, 10:54 AM

    And after you've read that, give yourself The Quiz!

    http://www.asktog.com/columns/022DesignedToGiveFitts.html

  • by deventis on 3/18/18, 11:05 AM

    Laws of UX has a nice overview of the different laws that exist in user experience! Fitt's law: https://lawsofux.com/fittss-law

  • by todd8 on 3/18/18, 8:41 PM

    On some early graphical computer user interface, I can’t remember which one, one could specify that the mouse cursor would “wrap” to the opposite edge. It was like the ultimate non-Fitt’s law configuration. I hated it when I tried it, I would lose the cursor and not be able to find it.

  • by macqm on 3/19/18, 5:21 PM

    Windows 8 Start UI was designed to take advantage of this. Theoretically it was great: when you open start menu the mouse pointer is in the bottom left corner, tiles close to you are wide and tall, tiles far from the pointer are smaller, wider at the bottom, narrower at the top. Hot corners were supposed to be easily accessible (infinite distance). Yet is was a failure, because uses were not familiar with it, it broke their habits.

  • by simula67 on 3/18/18, 2:57 PM

    Previous discussion : https://news.ycombinator.com/item?id=11208463

    I posted this in previous discussion too, a much simpler explanation : https://www.youtube.com/watch?v=E3gS9tjACwU

  • by rwmj on 3/18/18, 11:03 AM

    Clicks edge of screen above NetworkManager icon ... Confirms it's still broken in XFCE 4.

  • by walterbell on 3/18/18, 12:35 PM

    How does this work with radial menus and touch interfaces?

  • by dang on 3/18/18, 8:21 PM

    We merged the earlier discussion (https://news.ycombinator.com/item?id=16610903) into this one.

    I invited Kevin to repost his old article that was posted in 2007 but never got any discussion on Hacker News: https://hn.algolia.com/?query=Visualizing%20Fitts%27s%20Law&....