Fitt's law for mobile devices

14 Aug 2006 - 9:30am
8 years ago
10 replies
851 reads
Barbara Ballard
2005

I've been working on articulating some of the theory behind mobile UI
design, by examining current algorithms and heuristics from the entire
field. I'd like some feedback (blog post at [1]). I've got further
analysis with specific design recommendations at [2], but that is a
topic for a different message.

Mouse driven interfaces (software) – the "large" controls are the
edges of the screen, as they are really infinitely large in one
direction. Corners are larger still. Thus frequently used items should
go around the edges. The existence of a cursor gives a precise
definition of "close", so contextual menus can be truly context
driven.

Mouse driven web sites – when a link is activated, the screen changes,
possibly completely, and the edges of the screen are not accessible by
the web page. Thus "where the cursor is" is the largest target, and
cultural visual scanning practices are used to place most elements.
Consistency between pages helps the visual scanning process. Note:
modern web development techniques allow for an interaction style more
closely resembling software.

Stylus driven interfaces (small screens) – the concept of "distance"
is almost meaningless, as the entire screen is smaller than the hand
and there is no cursor. Thus size and predictability of location
become the key issues for speed of target acquisition.

Scroll-and-select interfaces (small screens) – the number of
keypresses to access a target is a good measure of distance, and size
is reasonably represented by whether the target is currently displayed
or not. As more devices display several font sizes, target size will
be a combination of visibility and target size.

[1] http://www.littlespringsdesign.com/blog/2006/08/07/fitts-law-and-softkey-optimization/
[2] http://www.littlespringsdesign.com/blog/2006/01/17/fitts-law-for-mobile-devices/

--
Barbara Ballard
barbara at littlespringsdesign.com 1-785-550-3650

Comments

14 Aug 2006 - 10:14am
Robert Hoekman, Jr.
2005

> Stylus driven interfaces (small screens) – the concept of "distance"
> is almost meaningless, as the entire screen is smaller than the hand
> and there is no cursor. Thus size and predictability of location
> become the key issues for speed of target acquisition.

I'd say Fitts' Law also applies to distance from start to finish. As in, the
fewer clicks it takes to get through a task, the better.

-r-

15 Aug 2006 - 3:16am
Bruce Esrig
2006

Fitts' law seems to be designed to model targeted navigation, in which the
issue is proper aim and coordination.

This scenario seems to involve some exploratory navigation, in which there
is a need to locate an item that is off-screen or hidden in a menu system.

The total time required to navigate might be the sum of these: the
exploration time plus any remaining time to touch the target.

Best wishes,

Bruce Esrig

At 11:30 AM 8/14/2006, Barbara Ballard wrote:
>[Please voluntarily trim replies to include only relevant quoted material.]
>
>Scroll-and-select interfaces (small screens) ­ the number of
>keypresses to access a target is a good measure of distance, and size
>is reasonably represented by whether the target is currently displayed
>or not. As more devices display several font sizes, target size will
>be a combination of visibility and target size.
>
>[1]
>http://www.littlespringsdesign.com/blog/2006/08/07/fitts-law-and-softkey-optimization/
>[2]
>http://www.littlespringsdesign.com/blog/2006/01/17/fitts-law-for-mobile-devices/
>
>--
>Barbara Ballard
>barbara at littlespringsdesign.com 1-785-550-3650

15 Aug 2006 - 4:51am
Peter Bagnall
2003

On 14 Aug 2006, at 16:30, Barbara Ballard wrote:
> I've been working on articulating some of the theory behind mobile UI
> design, by examining current algorithms and heuristics from the entire
> field. I'd like some feedback (blog post at [1]). I've got further
> analysis with specific design recommendations at [2], but that is a
> topic for a different message.

I know you asked for feedback on [1] but it's actually [2] that I had
issues with! [1] seems ok except I think your concept of "close" is a
bit confusing in the context of Fitt's law. Number of buttons presses
cannot be used as a measure of distance for Fitt's law.

Fitt's law was originally formulated as a way of predicting the time
taken to move of people's hands moving towards a target. It's been
used successfully to look at mouse movement, but that is an extension
to Fitt's law that has been validated and is still dealing with limb
movement and coordination.

in [2] you say...

"Stylus driven interfaces (small screens) – the concept of “distance”
is almost meaningless...."

I see what you're getting at, that the distance, being small, is less
important than the size of the target, and that's entirely correct,
but I'm a little uncomfortable with the "almost meaningless". If the
target is very small the distance will become important again. This
after all, is exactly what Fitt's law was originally all about. It
talks about the distance/target size ratio as being the determining
factor in time to target.

"Scroll-and-select interfaces (small screens) – the number of
keypresses to access a target is a good measure of distance."

Again, I see what you're saying, but in this case this is not Fitt's
law. There is no coordination to be done. If the thumb or finger is
already on the button, distance is zero, and Fitt's law is not
helpful. Instead it's more about cognitive issues. I would suggest
something like GOMS would be a more appropriate way of looking at
this, although I could be wrong there, it's not something I've ever
really used myself.

For Fitt's law distance is physical distance - as soon as you stop
talking about that you are no longer talking about Fitt's law. To me
it seems that you're pushing Fitt's law beyond it's validity. That
doesn't mean what you're saying is wrong, just that Fitt's law is not
supporting your case. I actually think your conclusions are correct!

Apologies if this seems overly nit-picking, but one reason many
people think that "studies" are dodgy isn't because the study itself
is poor, but due to over-generalisation of the results. Most studies
are pretty specific, and you have to be very careful when you
generalise to be sure your claims are still valid. Most of what is
said about Fitt's law in an HCI context is actually a number of
implications of Fitt's law in specific circumstances, many of which
have been validated experimentally in their own right. For example,
there's nothing in Fitt's law that says it will apply to mouse
movement. That has to be tested separately to establish it's validity
(and I'm pretty sure it has been although I don't have a reference to
hand).

Cheers
--Pete

----------------------------------------------------------
As long as people believe in absurdities they will continue
to commit atrocities.
Francois Marie Arouet (Voltaire), 1694 - 1778

15 Aug 2006 - 9:45am
Robert Hoekman, Jr.
2005

> For Fitt's law distance is physical distance - as soon as you stop
> talking about that you are no longer talking about Fitt's law. To me
> it seems that you're pushing Fitt's law beyond it's validity.
>

We did a usability study recently where users were asked to perform several
tasks in a web builder tool. Each of these tasks involved at least one new
window, hidden menu items, and out-of-context editing. Users would start on
one screen, choose something in a menu, which launched a new window, find
something in another menu, make the edit, and complete the task. What we
discovered, quite obviously, is that the further away the task's completion
point was from the task's starting point, the more difficult it was to
complete the task and the longer it took. This has a direct correlation to
Fitts' Law, even if the law wasn't meant to measure time. So, even if the
original intent was to measure only physical distance, the Law can be
adapted to include time as well. It "fits" way too well to ignore it. Time
is distance too.

May be a case of "the spirit of the law" winning out over "the letter of the
law", but it's hard to deny the connection.

-r-

15 Aug 2006 - 6:34pm
Peter Bagnall
2003

On 15 Aug 2006, at 16:45, Robert Hoekman, Jr. wrote:
> What we discovered, quite obviously, is that the further away the
> task's completion point was from the task's starting point, the
> more difficult it was to complete the task and the longer it took.

Indeed, that's is precisely what I would have expected too, but it's
still not Fitt's law. You can't use Fitt's law to predict this
effect. What you've found, by doing a small experiment is Hoekman's
law ;-)

> This has a direct correlation to Fitts' Law, even if the law wasn't
> meant to measure time.

If you'll forgive me for being even more picky (wow, is that
possible?!), it's not a correlation, it's an analogy.

> So, even if the original intent was to measure only physical
> distance, the Law can be adapted to include time as well. It "fits"
> way too well to ignore it. Time is distance too.

I have to disagree, the law cannot be adapted, that's exactly what
I'm objecting to. The law is derived from experimental data gained
under precise conditions. What you're suggesting is quite different
from those conditions and so the experiment that Fitt carried out
says absolutely nothing about it.

I agree that since time and space are analogous it is reasonable to
guess that a similar law may also exist for time. But until you
actually do that experiment you don't know if that assumption is
true. Science does not proceed by assumption. Since you have done an
experiment though, we now know that such a law does exist, but law is
*still* not Fitt's law. It's a whole new law (actually, I'd call it a
model, but I think I've probably split enough hairs for one day).

If you'd not done the experiment, for our purposes the assumption
would probably be safe, since it's pretty reasonable, but it would be
much more accurate to say "by analogy to Fitt's law we expect...."
instead of saying "Fitt's law says...".

> May be a case of "the spirit of the law" winning out over "the
> letter of the law", but it's hard to deny the connection.

It's very tempting to do this, but as soon as you do you invalidate
the science. It's fine to look for connections like that, but not
everything that's obvious is true, that's why the scientific method
exists.

I'm not trying to say that you shouldn't reason by analogy - all I'm
saying is that when you cite a scientific result be very careful that
you pay close attention to the limits of the experiment, and don't
use results beyond the limits of their validity. So if you're using
the "spirit" of the law, then you must say so, rather than claim to
be using the "letter" of the law - that's all I'm really trying to
get at at the end of the day.

Cheers
--Pete

----------------------------------------------------------
Always design a thing by considering it in its next larger
context - a chair in a room, a room in a house, a house in an
environment, an environment in a city plan.
- Eliel Saarinen, 1873 - 1950

Peter Bagnall - http://people.surfaceeffect.com/pete/

15 Aug 2006 - 6:52pm
Robert Hoekman, Jr.
2005

I can see what you're saying - really. I'm still not convinced I agree that
the law can't be interpreted to encompass time as distance, but the
separation isn't a bad idea either.

The fact that you said I've found "Hoekman's Law", of course, makes me want
to stop debating the point and just run with it. :) It seems way too obvious
to call it a law, but there are loads of laws that exist only to remind us
of the obvious. The fact, is, a lot of people need to have the obvious
pointed out to them.

-r-

On 8/15/06, Peter Bagnall <pete at surfaceeffect.com> wrote:
>
> On 15 Aug 2006, at 16:45, Robert Hoekman, Jr. wrote:
>
> What we discovered, quite obviously, is that the further away the task's
> completion point was from the task's starting point, the more difficult it
> was to complete the task and the longer it took.
>
>
> Indeed, that's is precisely what I would have expected too, but it's still
> not Fitt's law. You can't use Fitt's law to predict this effect. What you've
> found, by doing a small experiment is Hoekman's law ;-)
>
>
> This has a direct correlation to Fitts' Law, even if the law wasn't meant
> to measure time.
>
>
> If you'll forgive me for being even more picky (wow, is that possible?!),
> it's not a correlation, it's an analogy.
>
>
> So, even if the original intent was to measure only physical distance, the
> Law can be adapted to include time as well. It "fits" way too well to ignore
> it. Time is distance too.
>
>
> I have to disagree, the law cannot be adapted, that's exactly what I'm
> objecting to. The law is derived from experimental data gained under precise
> conditions. What you're suggesting is quite different from those conditions
> and so the experiment that Fitt carried out says absolutely nothing about
> it.
>
> I agree that since time and space are analogous it is reasonable to guess
> that a similar law may also exist for time. But until you actually do that
> experiment you don't know if that assumption is true. Science does not
> proceed by assumption. Since you have done an experiment though, we now know
> that such a law does exist, but law is *still* not Fitt's law. It's a whole
> new law (actually, I'd call it a model, but I think I've probably split
> enough hairs for one day).
>
> If you'd not done the experiment, for our purposes the assumption would
> probably be safe, since it's pretty reasonable, but it would be much more
> accurate to say "by analogy to Fitt's law we expect...." instead of saying
> "Fitt's law says...".
>
>
> May be a case of "the spirit of the law" winning out over "the letter of
> the law", but it's hard to deny the connection.
>
>
> It's very tempting to do this, but as soon as you do you invalidate the
> science. It's fine to look for connections like that, but not everything
> that's obvious is true, that's why the scientific method exists.
>
> I'm not trying to say that you shouldn't reason by analogy - all I'm
> saying is that when you cite a scientific result be very careful that you
> pay close attention to the limits of the experiment, and don't use results
> beyond the limits of their validity. So if you're using the "spirit" of the
> law, then you must say so, rather than claim to be using the "letter" of the
> law - that's all I'm really trying to get at at the end of the day.
>
> Cheers
> --Pete
>
> ----------------------------------------------------------
> Always design a thing by considering it in its next larger
> context - a chair in a room, a room in a house, a house in an
> environment, an environment in a city plan.
> - Eliel Saarinen, 1873 - 1950
>
> Peter Bagnall - http://people.surfaceeffect.com/pete/
>
>
>

16 Aug 2006 - 6:10am
Peter Bagnall
2003

Panu,

With Fitt's law behaviour I seem to remember that there is actually a
feedback loop involved here. It goes something like this as I recall.
You assess the distance between you hand and the target, then move
your hand towards the target. The greater the distance the faster you
move. This is dead reckoning, so when you think you've probably gone
most of the way there, you slow your hand down and reassess the
remaining distance. And you repeat this cycle until you hit the target.

There is a limit to how fast you can do this because each time you go
through the cycle you need to visually assess where your hand is with
respect to the target, and visual processing in the brain only goes
so fast. Likewise it takes time for your brain to send the commands
to your muscles.

So at each step you're dividing the remaining distance by some
factor. And mathematically, every time you divide or multiply
something by a constant factor at regular intervals you end up with a
logarithmic law. That's all logs really indicate.

By analogy with Hick's law you mention, in Fitt's you're subdividing
the remaining distance at each iteration, whereas with Hick's you're
subdividing the remaining options.

Log laws crop up all over the place simply because mathematically
they are very simple. Radioactive decay follows a log law for
example, but clearly it's not a related effect ;-)

Cheers
--Pete

On 16 Aug 2006, at 05:52, <panu.korhonen at nokia.com>
<panu.korhonen at nokia.com> wrote:

> [Please voluntarily trim replies to include only relevant quoted
> material.]
>
> Hello,
>
> Like Fitt's law, many other models in nature (and HCI) seem to be
> logarithmic. Why exactly this is the case, I won't start guessing, but
> this may be the reason why "the spirit of the law" of Fitt's law
> applies
> to other experiments too.
>
> For another logarithmic HCI related law, see Hick's law. Wikipedia on
> Hick's law: "Intuitively, one can reason that Hick's law has a
> logarithmic form because people subdivide the total collection of
> choices into categories, eliminating about half of the remaining
> choices
> at each step, rather than considering each and every choice one-by-
> one,
> requiring linear time."
>
> Regards,
> Panu
>
>> -----Original Message-----
>> From: discuss-bounces at lists.interactiondesigners.com
>> [mailto:discuss-bounces at lists.interactiondesigners.com] On
>> Behalf Of ext Robert Hoekman, Jr.
>> Sent: 16 August, 2006 03:52
>> To: Peter Bagnall
>> Cc: barbara at littlespringsdesign.com; discuss at ixda.org
>> Subject: Re: [IxDA Discuss] Fitt's law for mobile devices
>>
>> [Please voluntarily trim replies to include only relevant
>> quoted material.]
>>
>> I can see what you're saying - really. I'm still not convinced
>> I agree that the law can't be interpreted to encompass time as
>> distance, but the separation isn't a bad idea either.
>>
>> The fact that you said I've found "Hoekman's Law", of course,
>> makes me want to stop debating the point and just run with it.
>> :) It seems way too obvious to call it a law, but there are
>> loads of laws that exist only to remind us of the obvious. The
>> fact, is, a lot of people need to have the obvious pointed out to
>> them.
>>
>> -r-
>>
>> On 8/15/06, Peter Bagnall <pete at surfaceeffect.com> wrote:
>>>
>>> On 15 Aug 2006, at 16:45, Robert Hoekman, Jr. wrote:
>>>
>>> What we discovered, quite obviously, is that the further away the
>>> task's completion point was from the task's starting point, the more
>>> difficult it was to complete the task and the longer it took.
>>>
>>>
>>> Indeed, that's is precisely what I would have expected too, but it's
>>> still not Fitt's law. You can't use Fitt's law to predict
>> this effect.
>>> What you've found, by doing a small experiment is Hoekman's law ;-)
>>>
>>>
>>> This has a direct correlation to Fitts' Law, even if the law wasn't
>>> meant to measure time.
>>>
>>>
>>> If you'll forgive me for being even more picky (wow, is that
>>> possible?!), it's not a correlation, it's an analogy.
>>>
>>>
>>> So, even if the original intent was to measure only physical
>> distance,
>>> the Law can be adapted to include time as well. It "fits"
>> way too well
>>> to ignore it. Time is distance too.
>>>
>>>
>>> I have to disagree, the law cannot be adapted, that's
>> exactly what I'm
>>> objecting to. The law is derived from experimental data gained under
>>> precise conditions. What you're suggesting is quite different from
>>> those conditions and so the experiment that Fitt carried out says
>>> absolutely nothing about it.
>>>
>>> I agree that since time and space are analogous it is reasonable to
>>> guess that a similar law may also exist for time. But until you
>>> actually do that experiment you don't know if that
>> assumption is true.
>>> Science does not proceed by assumption. Since you have done an
>>> experiment though, we now know that such a law does exist,
>> but law is
>>> *still* not Fitt's law. It's a whole new law (actually, I'd
>> call it a
>>> model, but I think I've probably split enough hairs for one day).
>>>
>>> If you'd not done the experiment, for our purposes the assumption
>>> would probably be safe, since it's pretty reasonable, but it
>> would be
>>> much more accurate to say "by analogy to Fitt's law we expect...."
>>> instead of saying "Fitt's law says...".
>>>
>>>
>>> May be a case of "the spirit of the law" winning out over
>> "the letter
>>> of the law", but it's hard to deny the connection.
>>>
>>>
>>> It's very tempting to do this, but as soon as you do you invalidate
>>> the science. It's fine to look for connections like that, but not
>>> everything that's obvious is true, that's why the scientific
>> method exists.
>>>
>>> I'm not trying to say that you shouldn't reason by analogy - all I'm
>>> saying is that when you cite a scientific result be very
>> careful that
>>> you pay close attention to the limits of the experiment, and
>> don't use
>>> results beyond the limits of their validity. So if you're using the
>>> "spirit" of the law, then you must say so, rather than claim to be
>>> using the "letter" of the law - that's all I'm really trying
>> to get at at the end of the day.
>>>
>>> Cheers
>>> --Pete
>>>
>>> ----------------------------------------------------------
>>> Always design a thing by considering it in its next larger
>> context - a
>>> chair in a room, a room in a house, a house in an environment, an
>>> environment in a city plan.
>>> - Eliel Saarinen, 1873 - 1950
>>>
>>> Peter Bagnall - http://people.surfaceeffect.com/pete/
>>>
>>>
>>>
>> ________________________________________________________________
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----------------------------------------------------------
It does not require a majority to prevail, but rather an
irate, tireless minority keen to set brush fires in people's minds.
- Samuel Adams, 1722 - 1803

16 Aug 2006 - 11:17am
Doug Anderson
2004

Hi Robert,

Don't worry, I won't try to convince you (though I *am* convinced).

Unlike Fitt's law, which essentially describes characteristics of hand-eye coordination, effects of time displacement within a task seem to me to be subject to characteristics of working memory and cognition. I would look to research in those areas for the bases of applicable models of human behavior.

As you say, it seems obvious that increasing displacement in time would reduce performance. However, there may be other independent variables that are significant in any particular task context. Drawing an analogy to Fitt's law would shed no light on such variables. Looking into memory & cognition would be likely to suggest what sorts of variables might be significant, including time displacement, and why.

That would seem to provide a better foundation for an explanatory model. Just my 2 cents worth.

Peace,
Doug Anderson
Mayo Clinic
Rochester, MN

Opinions expressed are necessarily mine, not necessarily those of the Mayo Foundation.

Original message:
Date: Tue, 15 Aug 2006 17:52:23 -0700
From: "Robert Hoekman, Jr." <rhoekmanjr at gmail.com>
Subject: Re: [IxDA Discuss] Fitt's law for mobile devices
To: "Peter Bagnall" <pete at surfaceeffect.com>
Cc: barbara at littlespringsdesign.com, discuss at ixda.org

I can see what you're saying - really. I'm still not convinced I agree that the law can't be interpreted to encompass time as distance, but the separation isn't a bad idea either.

The fact that you said I've found "Hoekman's Law", of course, makes me want to stop debating the point and just run with it. :) It seems way too obvious to call it a law, but there are loads of laws that exist only to remind us of the obvious. The fact, is, a lot of people need to have the obvious pointed out to them.

-r-

16 Aug 2006 - 11:44am
Robert Hoekman, Jr.
2005

This is the statement I've latched onto:

"The time it takes to complete a task is a function of the number of steps
involved in the task and the relative complexity of each step."

I will certainly do what I can to prove or disprove this statement, and it
might need some tweaking as far as wording goes. One could argue that the
time it takes to complete a task also has to do with the general willingness
of the person to complete the task, and the person's ability to comprehend
each step and complete it successfully with reasonable effort.

So, right now it's a hypothesis. :)

-r-

On 8/16/06, Anderson, Douglas W. <Anderson.Douglas at mayo.edu> wrote:
>
> Hi Robert,
>
> Don't worry, I won't try to convince you (though I *am* convinced).
>
> Unlike Fitt's law, which essentially describes characteristics of hand-eye
> coordination, effects of time displacement within a task seem to me to be
> subject to characteristics of working memory and cognition. I would look to
> research in those areas for the bases of applicable models of human
> behavior.
>
> As you say, it seems obvious that increasing displacement in time would
> reduce performance. However, there may be other independent variables that
> are significant in any particular task context. Drawing an analogy to Fitt's
> law would shed no light on such variables. Looking into memory & cognition
> would be likely to suggest what sorts of variables might be significant,
> including time displacement, and why.
>
> That would seem to provide a better foundation for an explanatory model.
> Just my 2 cents worth.
>
> Peace,
> Doug Anderson
> Mayo Clinic
> Rochester, MN
>
> Opinions expressed are necessarily mine, not necessarily those of the Mayo
> Foundation.
>
> Original message:
> Date: Tue, 15 Aug 2006 17:52:23 -0700
> From: "Robert Hoekman, Jr." <rhoekmanjr at gmail.com>
> Subject: Re: [IxDA Discuss] Fitt's law for mobile devices
> To: "Peter Bagnall" <pete at surfaceeffect.com>
> Cc: barbara at littlespringsdesign.com, discuss at ixda.org
>
> I can see what you're saying - really. I'm still not convinced I agree
> that the law can't be interpreted to encompass time as distance, but the
> separation isn't a bad idea either.
>
> The fact that you said I've found "Hoekman's Law", of course, makes me
> want to stop debating the point and just run with it. :) It seems way too
> obvious to call it a law, but there are loads of laws that exist only to
> remind us of the obvious. The fact, is, a lot of people need to have the
> obvious pointed out to them.
>
> -r-
>
>

17 Aug 2006 - 12:10pm
Robert Hoekman, Jr.
2005

After a little debate, I've revised it:

"The difficulty of completing a task is a function of the number of steps
involved in the task and the time it takes to perform each step."

It obviously still needs to be proven out, but this is a much more accurate
statement about the original observation.

-r-

On 8/16/06, Robert Hoekman, Jr. <rhoekmanjr at gmail.com> wrote:
>
> This is the statement I've latched onto:
>
> "The time it takes to complete a task is a function of the number of steps
> involved in the task and the relative complexity of each step."
>
> I will certainly do what I can to prove or disprove this statement, and it
> might need some tweaking as far as wording goes. One could argue that the
> time it takes to complete a task also has to do with the general willingness
> of the person to complete the task, and the person's ability to comprehend
> each step and complete it successfully with reasonable effort.
>
> So, right now it's a hypothesis. :)
>
> -r-
>
>
>
>
> On 8/16/06, Anderson, Douglas W. <Anderson.Douglas at mayo.edu > wrote:
> >
> > Hi Robert,
> >
> > Don't worry, I won't try to convince you (though I *am* convinced).
> >
> > Unlike Fitt's law, which essentially describes characteristics of
> > hand-eye coordination, effects of time displacement within a task seem to me
> > to be subject to characteristics of working memory and cognition. I would
> > look to research in those areas for the bases of applicable models of human
> > behavior.
> >
> > As you say, it seems obvious that increasing displacement in time would
> > reduce performance. However, there may be other independent variables that
> > are significant in any particular task context. Drawing an analogy to Fitt's
> > law would shed no light on such variables. Looking into memory & cognition
> > would be likely to suggest what sorts of variables might be significant,
> > including time displacement, and why.
> >
> > That would seem to provide a better foundation for an explanatory model.
> > Just my 2 cents worth.
> >
> > Peace,
> > Doug Anderson
> > Mayo Clinic
> > Rochester, MN
> >
> > Opinions expressed are necessarily mine, not necessarily those of the
> > Mayo Foundation.
> >
> > Original message:
> > Date: Tue, 15 Aug 2006 17:52:23 -0700
> > From: "Robert Hoekman, Jr." <rhoekmanjr at gmail.com>
> > Subject: Re: [IxDA Discuss] Fitt's law for mobile devices
> > To: "Peter Bagnall" <pete at surfaceeffect.com>
> > Cc: barbara at littlespringsdesign.com, discuss at ixda.org
> >
> > I can see what you're saying - really. I'm still not convinced I agree
> > that the law can't be interpreted to encompass time as distance, but the
> > separation isn't a bad idea either.
> >
> > The fact that you said I've found "Hoekman's Law", of course, makes me
> > want to stop debating the point and just run with it. :) It seems way too
> > obvious to call it a law, but there are loads of laws that exist only to
> > remind us of the obvious. The fact, is, a lot of people need to have the
> > obvious pointed out to them.
> >
> > -r-
> >
> >
>

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