

RE: internet access via a touch screen

From: Kasday, Leonard <kasday@att.com>
Date: Tue, 3 Feb 1998 09:52:17 -0500
Message-Id: <F9AE637AED42D01187B400A0C913772E8F9848@mailsrvd.ho.att.com>
To: w3c-wai-ig@w3.org
re your question

	> Does anyone have any thoughts on ways around the web access
> which arise when using a touch screen (without a physical keyboard).  


This is interesting from a disability standpoint because

- an able-bodied (or temporarily able bodied, TAB) person using a touch
screen encounters functional limitations similar to those of a person
with a motor impairment using a device such as a mouse or trackball.    

- the methods needed to help a TAB person handle closely spaced links
with a touch screen may help people with motor impairments handle the
more widely spaced links on that touch screen.

- some  of the approaches (#3, 4 below) only work well if the page was
designed to be accessible for people with who have low vision and/or are

- the on-screen keyboard needed for alpha input is like those used in
some disability apps.

In short, a case for universal design.

And now for some suggestions....

Aside from Alpha input,  the main problem for using a touch screen on a
web page is difficulty of hitting the target accurately.  There are a
number of ways around this:

1. If you have a force sensitive touch screen, then you can position a
pointer by lightly moving your finger until the pointer lines up with
the target and then pressing harder.  However, I don't know of any
commercially available force sensitive touch screens. 

 (I designed a couple of such screens a while back but they are not
currently manufactured: cf. 

patent   4,710,760 Photoelastic touch-sensitive screen 
patent   4,484,179 Touch position sensitive surface 

Hmmm.  I wonder how these would work for a person with motor
impairments?  Maybe use to smooth tremors?  Well, that's off the point
at the moment)

2. There's also the "drag tap" interface like what's used in some
laptops with touch pads.  You drag the pointer to the screen by sliding
your finger to the spot and then tap (anywhere) to activate.   So you
can get more accuracy than if just touching the screen activated the
link.   If this is for casual walk-up use though, some people might not
catch on.  Also, this could cause problems for person with motor

3. Getting to your question about doctoring the pages, you could
decrease the need for fine positioning by enlarging all the text links
by increasing the font size, and magnfiy all image maps till targets are
separated.   This would screw up layout of some web pages unless...

and this is interesting...

the author of the web page designed it with ACCESSIBILITY  in mind to
allow it to take larger font sizes.  E.g. by avoiding a backbround image
that's supposed to line up with text, e.g. the left hand menu bar idiom.

4. Another way to doctor the page would add javascript whereever there
are closely spaced links so that clicking on one of the lines brings up
a menu of the nearby links.   Again, this works best if the page was
designed to be accessible: with links that make sense when read alone
out of context (to avoid a menu that says

click here
click here 
click here

And ALT text for each AREA in an image map.


There's also the issues of making sure tha people with disabilities can
use these screens, especially if you're looking a kiosks.

For people who are blind, you'll need a speech interface, e.g. Gregg
Vanderheiden's speech system.  

Plus, it should be possible to contol the link spacing criterion so that
people with motor impairments can get assistance.  

In general, some work would be needed to help people with motor
impairments use the screen.  E.g. anti bounce, motion averaging.

Also, you'll need an onscrren keyboard for alpha input.


kasday@att.com         phone 732 949 2693

Leonard R. Kasday
Room 1J-316A
AT&T Laboratories
101 Crawfords Corner Rd.
Holmdel NJ 07733
Received on Tuesday, 3 February 1998 09:52:21 UTC
