setting pointer location

Richard Gaskin ambassador at fourthworld.com
Sat Dec 28 15:20:00 EST 2002


> I personally think the HIG guideline against moving the cursor should
> NOT be accepted at face value: if it makes sense to you in your
> design, do it and see how it turns out.

It's enough to give one Fitts (sorry to perpetuate one of the most tired
puns in the usability word).  :)

Fitts' Law says that the time to acquire a target with the mouse is a
function of the distance to and size of the control, with extra
consideration given to the natural "backstop" provided by the monitor
boundaries.

But none of the readings I could find on Fitts' Law discusses the fourth
factor described here: the time it takes the user to discover what happened
to their pointer.

The aim of moving the pointer away from where the user placed it is to
shorten Fitts' first factor (distance), which by itself makes rational
sense.

But given that this occurs in a context in which all other applications and
the OS itself regard the user's placement of the pointer as sacred, the
user's expectations may require re-learning how to use (or in this case not
use) the pointer.  All of the HIGs include "The user is in control" as a
core principle, and with such a pervasive convention of leaving the
pointer's location to the user it may not be a mistake to consider the
pointer as "belonging" to the user.  Without a good testing lab and some
time on our hands we can't know if this is a benefit or a detriment.

Admittedly conservative on such things, before diving into uncharted waters
I'd want to at least make sure the areas of known improvement are covered:

- Could the size of the controls be made larger?

- Does the workflow of the form follow the reading order order of the target
audience (left-to-right, top-to-bottom for Western users)?

- Can the form be traversed entirely from the keyboard?

This latter consideration is a cornerstone of the Win HIG, and given the
difficulty of moving from mouse to keyboard and back again may yield the
most significant improvement if not already covered.

More on Fitts' Law:

A Quiz Designed to Give You Fitts
<http://www.asktog.com/columns/022DesignedToGiveFitts.html>

KDE User Interface Guidelines: Fitts' Law
<http://developer.kde.org/documentation/design/ui/fittslaw.html>

More at Google:
<http://www.google.com/search?q=fitts%27+law>

If you find research on the affect of changing pointer location from the
user I'd love to read it.  Frankly I was surprised I could find nothing on
it.

-- 
 Richard Gaskin 
 Fourth World Media Corporation
 Developer of WebMerge 2.1: Publish any database on any site
 ___________________________________________________________
 Ambassador at FourthWorld.com       http://www.FourthWorld.com
 Tel: 323-225-3717                       AIM: FourthWorldInc




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