Designing Human-Computer Interfaces for Quadriplegic People 
From: ACM Transactions - May + June 2003 - page 9
By: Constantine E. Steriadis and Philip Constantinou
conster@mobile.ece.ntua.gr
School of Electrical and Computer Engineering
National Technical University of Athens
Athens, Greece

This abstract is from a recent issue or forthcoming issue of ACM'S
Transactions of Computer Human Interaction (ToCHI). It is included here to
alert interactions readers to what research is being done in the field of
Computer Human Interaction. 

A link to the full text of the article in PDF can be found at:
http://portal.acm.org/citation.cfm?id=772049


Abstract

The need for participation in an emerging Information Society has led to
several research efforts for designing accessibility solutions for disabled
people. In this paper we present a method for developing Human-Computer
Interfaces (HCIs) for quadriplegic people in modern programming environments.
The presented method accommodates the design of scanning interfaces with
modern programming tools, leading to flexible interfaces with improved
appearance and it is based on the use of specially designed software objects
called "wifsids" (Widgets For Single-switch Input Devices). The wifsid
structure is demonstrated and 4 types of wifsids are analyzed. Developed
software applications are to be operated by single-switch activations that
are captured through the wifsids, with the employment of several modes of the
scanning technique. We also demonstrate the "Autonomia" software application,
that has been developed according to the specific methodology. The basic
snapshots of this application are analyzed, in order to demonstrate how the
wifsids cooperate with the scanning process in a user-friendly environment
that enables a quadriplegic person to access an ordinary computer system.  


Computer and system manufacturers often say that designing applications for
users with disabilities is not cost-effective. Most computer systems are
designed for users who are not disabled; therefore, systems that address
disabled users need special interfaces in order to be accessible. In this
paper we present a method for developing human-computer interfaces for
quadriplegic people in modern programming environments, provided that they
can perform single-switch signals. Using a scanning technique,
"single-switch" users can sequentially highlight items that are laid out
spatially on screen and then select an item by activating a switch when the
target item is highlighted.  

Our method is based on the use of a specially issued software class called
"wifsid" (widget for single-switch input devices), which can be regarded as a
universal scan element. A wifsid is graphically represented by a combination
of a bitmap image, a label, and a 3-D frame. The scanning process does not
address how to turn a highlight on or off; each wifsid has its own mode of
highlighting. Users' inputs are captured through a 2-D array of wifsids; the
arrays are then scanned and forwarded to the selected wifsid for further
handling. The wifsid-array and the applied scan modes are encoded by special
data structures, resulting in flexible and efficient, graphically improved,
scanning-based interfaces. Also in the paper we compare a newly developed
scan mode (diagonal selection mode) with three common scan modes (cell, row,
and submatrix selection modes) and include some basic principles that the
designers of such interfaces should keep in mind.  

This methodology was applied to the development of our assistive software
application called Autonomia. Autonomia was designed for Microsoft Windows
environments and can be operated by a person who uses one switch. In
accordance with the multiple windows that appear in ordinary graphical user
interface (GUI) applications, multiple "frames" have been incorporated into
Autonomia to enable a user to perform several tasks. Figures 1 a & b show
snapshots of the frames that handle the two most common tasks for scanning
systems: mouse and keyboard emulation. These snapshots show that our
methodology can provide user-friendly interfaces in harmony with the spirit
of modern GUI interfaces that most people use today. 

A home user has been using Autonomia for almost two years, with encouraging
results about its efficiency. Our patient is a 35-year-old male who has been
suffering from amyotrophic lateral sclerosis (ALS) since 1997. He is
currently bedridden and lost the ability to speak four years ago. We have
acquired valuable feedback that helped us improve the application and design
more useful and efficient frames. Using Autonomia's keyboard emulation frame
as a testbed, we also conducted a series of tests in order to evaluate the
importance of several parameters of the scan process and how they affect a
frame's overall performance. Our tests proved that optimization of the
matrices' layout and use of a proper scan-mode greatly help speed up the
frame's performance. The diagonal selection mode seemed to perform well in
the tests, although the subjects of our tests experienced some difficulties
in becoming familiar with the mode.


Captions:

Figures 1a & b. Snapsjots of Autonomia's mouse and keyboard emulation frames.

(a) Snapshot of the mouse-emulation frame. The wifsid that causes the cursor
to move downwards is highlighted. 

(b) Snapshot of the keyboard-emulation frame with word-prediction activated.
The wifsids are located on a 9x9 matrix and the 7th row is highlighted.

