Thinking ahead: some FC7 ideas - Initial concept

Máirín Duffy duffy at redhat.com
Thu Oct 19 14:11:01 UTC 2006


Nicu Buculei wrote:
> Luya Tshimbalanga wrote:
>> I decided to take some initiative to do a mockup for future Fedora
>> desktop. Description available on :
>> http://fedoraproject.org/wiki/LuyaTshimbalanga/mockups
> 
> This is not the first mockup I see where the menu in anchored to the 
> right. I wonder about its usability: Fitts' law states the points closer 
> to the corner are easier to reach, so in this case "Help" is the easiest 
> to reach menu option and the position of "File", which arguably is the 
> most used for some applications, is unpredictable.
> Can we have input from an usability expert?

Actually, (so here's where my MS in HCI comes in lol), I am not a big 
fan of applying Fitts' law to the desktop. I've read the original Fitts 
paper. Fitts' law was developed to basically figure out mathematically 
bomb 'target acquisition' (I believe for WWII), I kid you not. It 
basically says this:

The *bigger* a target is (the 'W' in the formula)
The *closer* a target is to you (the 'D' in the formula)
The more quickly you will hit the mark. The further away and smaller a 
target, the more time you have to spend aiming to get an accurate shot. 
So the time is actually aiming time.

Where this applies to computer desktop usage - specifically the corners 
of the screen is the following: Basically, any 'target' along the edge 
of the monitor is easier to acquire. This is because you can slam your 
mouse pointer towards any edge of the screen and it will stop for you - 
it won't go beyond the boundaries of the screen. The corners are 
supposedly the easiest points on the screen to reach with your mouse 
because you slam the mouse pointer towards a corner and *both* edges 
will 'stop' the pointer.

(The corner is easier as a single point to hit than a single point along 
the edge because you have left-right jitter to worry about in your 
aiming along the edge. With the corner you dont have that jitter because 
you have two edges stopping the cursor. If a target along the edge is 
large enough, though, it really isn't an issue.)

 From all this, the hardest point on the screen to hit at any given 
point is relative to the starting mouse cursor position. This can be 
applied in thinking about the placement of different menu items/buttons 
used in a single task, but in general isn't really applicable.

So! To get back to the point - Fitts' law isn't really a good argument 
against the placement of the menu items in Luya's mockup, but convention 
is a good argument against it. People are used to that menu being in the 
upper left. I'm sure over time they'll get used to using it but the more 
we stray from established conventions the harder Fedora is going to be 
to adopt.

~m




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