Fitts’ Law Misunderstood

Fitts’ Law is being thrown around quite often. Some people seem to think that it is all about how the edges of the screen and especially the corners are easy/fast to hit with the pointer. We have to thank Tog for that😉 This is at least not entirely wrong, but I also saw claims it would have to do with targets becoming harder to hit if you place other targets in close proximity.

It really only covers: The time to acquire a target is a function of the distance to and size of the target. It has to be noted that this does only refer to linear movement, so the size of the target has to be measured along the axis of movement.

Here’s a nice article with pictures (and the actual formula).

About thorwil
I'm a designer from Germany. My main interests are visual and interaction design, free/open-source software and (electronic) music.

13 Responses to Fitts’ Law Misunderstood

  1. Thank you.

    I’ll note that if you put in land mines next to the target (say, a destructive close action), the effective size of the target in the user’s mind will decrease, and they’ll slow down accordingly.

  2. I don’t need no law by no crazy Irish to tell me that putting a CLOSE next to something else is being a bad thing.

    Can I get some chips with that shake?

  3. Conscious User says:

    The fact that the formal definition of Fitt’s Law does not *directly* mentions the problem of close targets does not mean that it’s not related to it.

    The window buttons and the menubar items are small objects, both sets are distributed in the same way (horizontal), and typically the mouse will quickly come from the center of the window (e.g. in a diagonal direction).

    Therefore, as a direct consequence of Fitt’s Law formula, the diference of time needed to hit a window button or a menu item is negligible: the difference in distance is negligible because of the horizontal distribution of both rows and the the sizes are negligible. Specially considering that a lot of users tend to reduce the default font size.

    Two movements often repeated eventually become “automatic” for the user. In order not to confuse those two movements and execute one when you actually wanted to execute the other, there are two things that can be used to differentiate them: direction and time needed to complete the movement.

    The current placement of window buttons in Lucid effectively kills the direction difference, leaving only time. But, as stated above, Fitt’s Law effectively kills time as well as a tool for differentiating.

    So, in conclusion, Fitt’s Law *has*, in fact, “to do with targets becoming harder to hit if you place other targets in close proximity”. It’s just boring having to type all the words above every single time you mention it.🙂

    • thorwil says:

      I severely doubt that all that many of the people who use the term could write such an explanation and actually have that in mind.

      Furthermore, I was not referring to just the buttons issue, excessive and erroneous use happened long before.

      • Conscious User says:

        Thorsten, I understand, but my point was that your post gives a strong impression that “if you are using Fitts’ Law to justify separating targets, you are automatically wrong”, which is not true.

  4. Look, complaining about whether or not this meets Fitts Law is what is called a shaming tactic. It allows the person to ignore the ACTUAL complaint and distract to something else.

    STOP IT you nimrods. Understand no one gives two hoots about whether this is ACTUALLY a Fitt’s Law circumstance. All we care about is that you stop trying to muck up our OS with stupid childish changes that only a poopiehead would come up with.

    • thorwil says:

      Your comments are ugly and don’t speak well of your manners or cognitive abilities.

      I didn’t even mention the window button issue. I don’t defend the experiment or actual change it might become. So far neither Ivanka’s posts nor the flaming in opposition have been convincing.

      I’m not part of the design team.

  5. loneswimmer says:

    Isn’t this a Planet Ubuntu blog dancing around the real issue?

    Current Quotes on various Planet Ubuntu blogs right now:

    “What’s wrong with there being change for the sake of change?” – Brian Curtis.

    Seriously? How does one even answer that?

    “I for one am happy that Canonical has finally decided to make some decent UI changes to Ubuntu, because thats something that I get to look forward to on a constant basis as I test of the newest versions of Ubuntu. There are too many lazy users out there that just aren’t willing to accept the changes because IMO they have gotten into such a routine with their daily computer lifestyles that any and all changes are the straw that broke the camels back.” – also Brian Curtis.

    Hey, got forbid some real issues might get fixed. (Nautilus’ awful layout [from GNOME upstream},slow USB transfer rates, “Endless loading” in Nautilus, large dataset transfer hangs, etc, these are just the major bugs I have, most of them a few release old)

    If it wasn’t for Scott Ritchie, it seems Planet Ubuntu would be pretending there was no issue, that the users weren’t angry,

    “Having said what I have so far, I’m all in favour of making big, bold changes. If Canonical puts this much effort into the design of every release, and if they can find a way to involve the community as well” – Jonathon Carter

    Well, that’s exactly what they didn’t do. Involve the community on the button issue. 1 day before freeze they land this, then ignore it when there’s a storm.

    • thorwil says:

      No, this isn’t dancing around the real issue, it’s just about another issue.

      Must everything be solely about the window buttons now? You mention other things that would be more important yourself …

      • Mumbwa says:

        How Fitt’s law applies to what people have been talking about is that if you put something (anything) in the corner that effectively makes it a bigger Fitt’s Law target because you can overshoot.

        Other people think that at this point because screens have gotten bigger it’s better to put things next to each other on the left it’s better. Because Fitts law says that you’ll be able to click on them faster.

        Other people think that maybe if it’s too easy to click on the things you accidentally do it which might cause something you didn’t want to happen.

        Those things are buttons.

        • thorwil says:

          @Mumbwa:

          There are by default panels on top and bottom, not leaving any corner for the any part of any window. Left or right screen edge can only help with the outermost button of a maximized window (otherwise the outermost button doesn’t touch the edge and you get the resize handle on the side of the window).

          How about some research and thought before commenting?

  6. Alex says:

    What a bunch of friendly faces.

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