Abstract
The objective of this special introductory
seminar is to provide newcomers to Human-
Computer Interaction (HCI) with an
introduction and overview of the field. The
material will begin with a brief history of the
field, followed by presentation and discussion of
how good application development methods pull
on the interdisciplinary technologies of HCI.
The topics will include the psychology of human-
computer interaction, psychologically-based
design methods and tools, user interface media
and tools, and introduction to user interface
architecture.
Keywords:
human-computer interaction,
usability engineering, human performance
engineering, cognitive modeling, analysis
methods, interaction styles, interaction
hardware, user interface software, user
interface management systems.
Introduction
The rapid growth of computing has made
effective human-computer interaction essential.
It is important for the growing number of
computer users whose professional schedules
will not allow the elaborate training and
experience that was once necessary to take
advantage of computing. Increased attention to
usability is also driven by competitive pressures
for greater productivity, the need to reduce
frustration, and to reduce overhead costs such
as user training. As computing affects more
aspects of our lives the need for usable systems
becomes even more important.
DESIGNING FOR HCI
Design in HCI is more complex than in many
other fields of engineering. It is inherently
interdisciplinary, drawing on and influencing
diverse areas such as computer graphics,
software engineering, human factors and
psychology. Furthermore, the developer's task of
making a complex system appear simple and
sensible to the user is in itself a very difficult,
complex task
The principles for applying human factors to
machine interfaces became the topic of intense
applied research
during the 1940's, when equipment complexity
began to exceed the limits of human ability for
safe operation. However, the complexity of
computing and of software development projects
pose additional demands. An engineering
paradigm that is common to many other fields
can be generalized to a technical approach for
engineering usability in computing systems [1]
and is now in widespread use [2]. The paradigm
follows an iterative cycle through analysis,
design, implementation, and evaluation.
Usability engineering structures human factors
activity to work within software engineering
projects.
Development of usable systems draws on
technologies from user interface media, software
architecture, process and data modeling,
standards, and tools for modeling, building and
testing user interfaces. Each can be a topic of
research or application. These technologies will
be covered in the following sections on the
psychology of HCI and the computer science of
HCI.
THE PSYCHOLOGY OF HCI
Information about human performance enters
into the design of user interfaces from three
sources: empirical data about human
performance, theories of performance, and
methods of observing and analyzing HCI
systems. This portion of the overview will
introduce each of these sources, the benefits of
using them, and potential pitfalls to be avoided.
The empirical data of human performance can
be classified as being either basic (collected in
the service of basic psychology, usually in
laboratory administered, knowledge-lean tasks)
and applied (collected in the service of human
factors design problems, often on realistic
tasks). Further, these data can be classified as
being about individual performance or group
performance. A source book containing
summaries of much useful data, and references
to many more sources, called The Engineering
Data Compendium [3], will3be referred to
extensively for examples of such data and how it
can be used in design.
A seminal source of both a useful theory of
human performance and methods of analyzing
HCI tasks is The Psychology of Human-
Computer Interaction [4]. This session will
introduce the GOMS method of analysis detailed
in that work and several other cognitive- and
system-modeling techniques that have arisen in
the decade its publication. These techniques can
be used to predict the usability and learnability
of systems before they are built. We will discuss
how to use these techniques in concert with
rapid-prototyping and empirical testing for the
benefit of an HCI design. We will present a
directory of ongoing research in both
psychological theory and analysis methods
within the CHI community so that participants
will know where to look for theories and
methods applicable to their design problems.
THE COMPUTER SCIENCE OF HCI
As progress in HCI is making user interfaces
easier to learn and use, they are becoming
more difficult to build. Simple command line
interfaces were difficult to use but easy to
program. Modern direct manipulation and
virtual environment interfaces are easier to
understand and use, but harder to program,
largely because they have more possible
execution paths. The area of Computer
Science in HCI studies and develops the
abstractions, techniques, languages, and tools
to address this problem. This section of the
overview discusses research and practice in
the field of user interface software [5].
An important concept in user interface
software is to separate the design of an
interactive system into distinct levels, i.e., the
conceptual, semantic, syntactic, and lexical
levels, and to develop a design for each level
[6]. Another significant concept is the user
interface management system (UIMS), which
provides a separate software component that
conducts all interactions with the user,
distinct from the application program that
performs the underlying task [7]. It is
analogous to a database management system
in that it separates a function used by many
applications and moves it to a shared
subsystem. This approach separates the
problem of programming the user interface
from each individual application and permits
some of the effort of designing tools for
human-computer interaction to be amortized
over many applications and shared by them.
Since user testing is an important part of good
interface design, techniques for rapidly
prototyping and modifying user interfaces are
needed. For this purpose, one needs methods
for specifying user interfaces that are precise,
so that the interface designer can describe and
study a variety of possible user interfaces
before building one, and that allow rapid,
perhaps automatic production of prototypes
for user testing.
In addition, we will consider interaction
styles, from conventional command language
and menu-based styles to newer direct
manipulation and virtual environment styles
and interaction techniques for using devices to
perform tasks in an interface.
In a graphical direct manipulation style of
user interface, a set of objects is presented on
a screen, and the user has a repertoire of
manipulations that can be performed on any
of them. This means that the user has no
command language to remember beyond the
standard set of manipulations, few cognitive
changes of mode, and a reminder of the
available objects and their states shown
continuously on the display. Examples are
spreadsheets, the Xerox Star desktop and its
descendants such as the Apple Macintosh,
and, of course, many video games.
Recent work has carried the user's illusion of
manipulating real objects still further. By
coupling a the motion of the user's head to
changes in the images presented on a head-
mounted display, the illusion of being
surrounded by a world of computer-generated
images or a virtual environment is created.
Hand-mounted sensors allow the user to
interact with these images as if they were real
objects located in space surrounding him or
her.
References
-
1. Butler, K. A. (1985) Connecting Theory and
Practice: A Case Study of Achieving Usability
Goals. In: Proceedings of CHI'85 Human Factors
in Computing Systems (April 14-18, 1985,San
Francisco, CA) ACM, pp. 85-88.
-
2. Wilkund, M. E. (1994) Usability in Practice:
How Companies Develop User-Friendly
Products, Cambridge, MA: Academic Press.
-
3. Boff, K. R. and Lincoln, J. E. (1988).
Engineering Data Compendium: Human
Perception and Performance vols 1-3. Harry G.
Armstrong Aerospace Medical Research
Laboratory, Wright-Patterson Air Force Base,
Ohio.
-
4. Card, S.K., Moran, T.P., and Newell, A.,
(1983) The Psychology of Human-Computer
Interaction, Hillsdale, NJ: Erlbaum.
-
5. Foley, J.D., van Dam, A., Feiner, S.K., and.
Hughes, J.F. (1990) Computer Graphics:
Principles and Practice, Reading, MA: Addison-
Wesley.
-
6. Myers, B. A. (1989) "User-interface Tools:
Introduction and Survey," IEEE Software, vol.
6(1) pp. 15-23.
-
7. Olsen, D.R. (1992) User Interface
Management Systems: Models and Algorithms,
San Mateo, CA: Morgan Kaufmann.
