[IxDA Discuss] "Interface-Free" Interface

[Miguel Gonzalez]

I can confirm Alan's points as I have been designing for touch screen kiosks for the last 6 years.

Let me pass some of my experience on each of his points...

- Size of the pointing device (fingertip vs cursor)
Touch screen guidelines says that on screen controls should be at least 50*50px, for a usual
resolution 1024*768px. As controls have to be oversized, you have less room on screen to fit other
controls. On that video you can see that the screen is much bigger than usual. Prices for touch
screens are getting down every year so in a near future we all could afford a big touch screen,
the problem is that no many people has room for a large screen on their desk, sure the desk could
be modified but that is one more harsh to make this system to success.

- Selection with the finger obscures the thing you're trying to select
No only the finger but your arms, they are on the way all the time. What is you are wearing a
loose jumper.

- Uncertainty on feedback
This is a big problem. With the most common input devices, mouse and keyboard, users feel the
mouse button or key depressing under their finger, this is a sensation that touch screen cannot
imitate.

- Dirt and oils
Depending of the touch screen technology, this may decrease the accuracy of the screen. Also,
between a dirty mouse button and a dirty screen I will always prefer the mouse, easy and faster to
clean up.

- Fatigue.
This is a big one. When you walk, when you sleep, when you eat, when you do normal life stuff, you
don't hold your arms on that position, meaning that we haven't develop the necessary muscles to
easily hold our arms on that position, it's painful after a few minutes.

Another point is the visual angle of the screen to the user. The actual technology for those
screens make the screen gives you different colour depending of the screen's angle. For a personal
computer at your home that's fine, you don't change your stature every day, but for a machine in a
public area, different people has different stature and that create a problem. This could be
easily solved by creating a kiosk where the final user can move the screen to adjust it to his or
her needs, the problem is that the final user is not aware of that capability or is afraid or
breaking the kiosk so they don't change the angle, they just abandon the kiosk.

Another problem on the screen inclination is erring on target, depending of the technology; the
reactive layer can be separated from the external screen by a few millimetres, this makes the user
to mistake many times, those few millimetres makes you to misjudge the distance and so to fail. 

Sure that the technology will sort out many of those problems, like making the reactive layer to
be at the same level than the screen protector glass, a new redesigned desk to increase ergonomic,
etc. This seems to be one more example of technology evolving much faster than human’s brain and
human’s body. Our brain and body is not got to change much in the few next centuries, all this new
technology will be fine for highly trained people but not for the casual one.

Again, we have to make clear who are we designing for, their environment, goals, etc. That touch
screen is really nice and the demonstration has been seen for many people on Internet over the
last 4 weeks, showing that people is really amazed and has a desire for this technology but that
doesn’t make it a successful technology, no many people will use a touch screen for more than an
hour.

I think I am missing an important point about this technology, the ability for multiple touch on
screen, I don’t recall the necessity for a multiple pointer, I think we don’t need it, but well,
it’s good to research and experiment, and this technology could bring something good in the
future, I hope.

Maglez.



--- Alan Wexelblat <awexelblat at gmail.com> wrote:

> [Please voluntarily trim replies to include only relevant quoted material.]
> 
> I can't find the references at this moment (they're on this ancient
> paper medium somewhere in my home office filing cabinet) but back in
> the late 80s the military went through a fad of touchscreen
> interfaces.  They were found to be highly error-prone and fatiguing.
> 
> Error sources include:
> - size of the pointing device (fingertip vs cursor)
> - selection with the finger obscures the thing you're trying to select
> - uncertainty on feedback.  The combination of physical feedback (does
> the screen flex in response to pressure?  If so how much and how does
> the user correlate that feedback with visual changes?) proved
> difficult for some users.
> - dirt and oils from human hands tended to introduce errors and
> obscure displays after extended use.
> 
> Fatigue sources included:
> - necesity for operators to hold their arms up
> - requirement to reach and retract arm on each completed interaction
> - positioning of the screen for touch required operators to change
> their head/body positions
> - operators tended to crane their necks sideways to try and confirm a
> touch that was full or partially blocked by their fingertips.
> 
> The tasks used were very similar to the original "Put That There"
> gestural interface, which is why I got interested in the research (I
> did my MS on gesture). The military operators used the touch screens
> in 1, 2, 4 and 8 hour shifts that matched their normal work schedules.
>  Even a one-hour shift was perceived as fatiguing.  This leads me to
> believe that touch interfaces are fine for casual interaction over
> short periods, but not really suitable for extended work.