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Human Computer Interaction

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As the aim of this lecture is to introduce you the study of Human Computer
Interaction, so that after studying this you will be able to:

. Describe the goals of HCI

. Define Usability goals

. Define User Experience goals

. Discuss the History and Evolution of HCI

Definition of HCI

“Human-Computer Interaction is a discipline concerned with the design, evaluation
and implementation of interactive computing systems for human use and with the
study of major phenomena surrounding them”

4.1 Goals of HCI

The term Human Computer Interaction (HCI) was adopted in the mid-1980s as a
means of describing this new field of study. This term acknowledged that the focus of
interest was broader than just the design of the interface and was concerned with all
those aspects that relate to the interaction between users and computers.
The goals of HCI are to produce usable and safe systems, as well as functional
systems. These goals can be summarized as ‘to develop or improve the safety, utility,
effectiveness, efficiency and usability of systems that include computers’ (Interacting
with computers, 1989). In this context the term ‘system’ derives from systems theory
and it refers not just to the hardware and software but to the entire environment---be it
organization of people at work at, home or engaged in leisure pursuits---that uses or is
affected by the computer technology in question. Utility refers to the functionality of a
system or, in other words, the things it can do. Improving effectiveness and efficiency
are self-evident and ubiquitous objectives. The promotion of safety in relation to
computer systems is of paramount importance in the design of safety-critical systems.
Usability, a key concept in HCI, is concerned with making systems easy to learn and
easy to use. Poorly designed computer system can be extremely annoying to users, as
you can understand from above described incidents. [2]
Part of the process of understanding user’s needs, with respect to designing an
interactive system to support them, is to be clear about your primary objective. Is it to
design a very efficient system that will allow users to be highly productive to their

work, or is to design a system that will be challenging and motivating so that it
supports effective learning, or is it some thing else? We call these talk-level concerns
usability goals and user experience goals. The two differ in terms of how they are
operational zed, i.e., how they can be met and through what means. Usability goals
are concerned with meeting specific usability criteria (e.g., efficiency) and user
experience goals are largely concern with explicating the quality of the user
experience (e.g., to be aesthetically pleasing).

Usability goals

To recap, usability in generally regarded as ensuring that interactive products are easy
to learn, effective to use, and enjoyable from user perspective.
It involves optimizing the interactions people have with interactive product to enable
them to carry out their activities at work, school, and in their everyday life. More
specifically, usability is broken down into the following goals:

. Effective to use (effectiveness)

. Efficient to use (efficiency)

. Safe to use(safety)

. Have good utility (utility)

. Easy to learn (learnability)

. Easy to remember how to use (memorability)
For each goal, we describe it in more detail.


It is a very general goal and refers to how good a system at doing what it is suppose to
do. [1]


It refers to the way a system supports users in carrying out their tasks. [1]


It involves protecting the users from dangerous conditions and undesirable situations.
In relation to the first ergonomics aspect, it refers to the external conditions where
people work. For example, where there are hazardous conditions---like x-rays
machines or chemical plants---operators should be able to interact with and control
computer-based system remotely. The second aspect refers to helping any kind of user
in any kind of situation avoid the danger of carrying out unwanted action accidentally.
It also refers to the perceived fears users might have of the consequences of making
errors and how this effects their behavior to make computer-based system safer in this
sense involves:

. Preventing the user from making serious error by reducing the risk of wrong
keys/buttons being mistakenly activated (an example is not placing the quit or
delete-file command right next to the save command on a menu.) and

. Providing users with various means of recovery should they make errors. Save
interactive systems should engender confidence and allow the users the
opportunity to explore the interface to carry out new operations.

Other safety mechanism include undo facilities and confirmatory dialog boxes that
give users another chance to consider their intentions (a well-known used in email
application is the appearance of a dialog box after the user has highlighted the
messages to be deleted, saying: “are you sure you want to delete all these messages?”)


It refers to the extent to which the system provides the right kind of functionality so
that user can do what they need or want to do. An example of a system with high
utility is an accounting software package providing a powerful computational tool that
accountants can use to work out tax returns. An example of a system with low utility
is a software drawing tool that does not allow users to draw free hand but forces them
to use a mouse to create their drawings, using only polygon shapes. [1]


It refers to how easy a system is to learn to use. It is well known that people do not
like spending a long time learning how to use a system. They want to get started
straight away and become competent at caring out tasks without to much effort. This
is especially so far interactive products intended for everyday use (for example
interactive TV, email) and those used only infrequently (for example, video
conferencing) to certain extent, people are prepared to spend longer learning more
complex system that provide a wider range of functionality (for example web
authoring tools, word processors) in these situations, CD ROM and online tutorials
can help by providing interactive step by step material with hands-on exercises.
However many people find these tedious and often difficult to relate to the tasks they
want to accomplish. A key concern is determining how much time users are prepared
to spend learning a system. There seems little point in developing a range of
functionality if the majority of users are unable or not prepared to spend time learning
how to use it. [1]


It refers to how easy a system is to remember how to use, once learned. This is
especially important for interactive systems that are used infrequently. If users haven’t
used a system or an operation for a few months or longer, they should be able to
remember or at least rapidly be reminded how to use it. Users shouldn’t have to keep
relearning how to carry out tasks. Unfortunately, this tends to happen when the
operation required to be learning are obscure, illogical, or poorly sequenced. Users
need to be helped to remember how to do tasks. There are many ways of designing
the interaction to support this. For example, users can be helped to remember the
sequence of operations at different stages of a task through meaningful icons,
command names, and menu options. Also, structuring options and icons so they are
placed in relevant categories of options (for example, placing all the drawing tools in
the same place on the screen) can help the user remember where to look to find a
particular tool at a given stage of a task. [1]
“Don’t Make me THINK, is the key to a usable product”

User experience goals

The realization that new technologies are offering increasing opportunity for
supporting people in their everyday lives has led researchers and practitioners to

consider further goals. The emergence of technologies (for example, virtual reality,
the web, mobile computing) in diversity of application areas (e.g., entertainment,
education, home, public areas) has brought about a much wider set of concerns. As
well as focusing primarily on improving efficiency and productivity at work,
interaction design is increasingly concerning itself with creating systems that are:

. Satisfying

. Enjoyable

. Fun

. Entertaining

. Helpful

. Motivating

. Aesthetically pleasing

. Supportive of creativity

. Rewarding

. Emotionally fulfilling
The goals of designing interactive products to be fun, enjoyable, pleasurable,
aesthetically pleasing and so on are concerned primarily with the user experience. By
this we mean what the interaction with the system feels like to the users. This
involves, explicating the nature of the user experience in subjective terms. For
example, a new software package for children to create their own music may be
designed with the primary objectives of being fun and entertaining. Hence, user
experience goals differs from the more objective usability goals in that they are
concerned with how user experience an interactive product from their perspective,
rather than assessing how useful or productive a system is from its own perspective.
The relationship between two is shown in figure.
Recognizing and understanding the trade-offs, between usability and user experience
goals, is important. In particular, this enables designers to become aware of the
consequences of pursuing different combinations of them in relation to fulfilling
different users’ needs. Obviously, not all of the usability goals and user experience
goals apply to every interactive product being developed. Some combination will also
be incompatible. For example, it may not be possible or desirable to design a process
control system that is both safe and fun. [1]


4.2 Evolution of HCI

Figure shows the main topics that make up the discipline of HCI. All HCI takes place
within a social and organizational context. Different kinds of applications are required
for different purposes and care is needed to divide tasks between humans and
machines, making sure that those activities and routine are allocated to machines.
Knowledge of human psychological and physiological abilities and, more important
still their limitations is important.
As shown in figure, this involves knowing about such things as human information
processing, language, communication, interaction and ergonomics. Similarly it is
essential to know about the range of possibilities offered by computer hardware and
software so that knowledge about humans can be mapped on to the technology
appropriately. The main issues for consideration on the technology side involve input
techniques, dialogue technique, dialogue genre or style, computer graphics and
dialogue architecture. This knowledge has to be brought together some how into the
design and development of computer systems with good HCI, as shown at the bottom
of the figure. Tools and techniques are needed to realize systems. Evolution also plays
an important role in this process by enabling designers to check that their ideas really
are what users want.

Supportive of
Efficient to
Easy to
to use
Easy to
Safe to
Have good


Three systems that provide landmarks along this evolutionary path are the Dynabook,
the Star and the Apple Lisa, predecessor of today’s Apple Macintosh machines. An
important unifying theme present in all three computer systems is that they provided a
form of interaction that proved effective and easy for novices and experts alike. They
were also easy to learn, and provided a visual-spatial interface whereby, in general,
objects could be directly manipulated, while the system gave immediate feedback.


Alan Kay designed the first object-oriented programming language in the 1970s.
Called Smalltalk, the programs were the basis for what is now known as windows
technology—the ability to open more than one program at a time on a personal
computer. However, when he first developed the idea, personal computers were only
a concept. In fact, the idea of personal computers and laptops also belongs to Kay. He
envisioned the Dynabook—a notebook-sized computer, with a keyboard on the
bottom and a high-resolution screen at the top.


The Xerox Star was born out of PARC's creative ferment, designing an integrated
system that would bring PARC's new hardware and software ideas into a
commercially viable product for use in office environments. The Star drew on the
ideas that had been developed, and went further in integrating them and in designing
for a class of users who were far less technically knowledgeable than the engineers

who had been both the creators and the prime users of many PARC systems (one of
PARC's favorite mottoes was "Build what you use, use what you build.") The Star
designers were challenged to make the personal computer usable for a community that
did not have previous computer experience.
From today's perspective, the Star screen looks rather unremarkable, and perhaps a bit
clumsy in its graphic design—a boxy model-T when compared to the highly styled
look of today's Taurus or Jaguar. What is notable from a historical perspective, of
course, is how much the Star does look like current screens and how little it looks like
the character-based and vector-drawing screens that preceded it.
The Star (Viewpoint) screen image The Star pioneered the now-familiar constellation
of icons, moveable scrollable windows, and inter-mixed text and graphic images. The
widely used graphic user interfaces (GUIs) of today are all variants of this original
design. (Source: Reprinted by permission from Jeff Johnson et al. Xerox Star, a
retrospective. IEEE Computer 22:9 (September, 1989), p. 13.)
The visible mechanisms on the Star display were backed up with a set of design
principles that grew out of a user-oriented design methodology and by a great deal of
empirical testing. Several principles were central to the Star design:

Direct manipulation

The core concept that distinguished Star (and other Alto programs) from the
conventional computer interfaces of their time was the use of a bitmapped screen to
present the user with direct visual representations of objects. In the Star’s desktop
metaphor, documents, printers, folders, collections of folders (file drawers and
cabinets), in and out boxes, and other familiar office objects were depicted on the
screen. To print a document, for example, the user could point (using the mouse) to
the icon for the document and the icon for the printer, while using a key on the
keyboard to indicate a Copy operation.

WYSIWYG (what you see is what you get)

In previously available programs for producing sophisticated graphical output—such
as drawings or page layout with multiple fonts—the user created and edited a
representation that looked like a programming language, and then compiled the
resulting program into a visible form. Alto programs pioneered a new style that Star
unified, in which the user works directly with the desired form, through direct
manipulation. The user makes changes by operating on a direct representation of what

will appear on the printed page. The Star user could intermix text, tables, graphs,
drawings, and mathematical formulas. In fact, most of the popular microcomputer
applications of today have not yet reached the degree of integration that Star offered
more than a decade ago.

Consistency of commands

Because a single development group developed all Star applications in a unified way,
it was possible to adhere to a coherent and consistent design language. The Star
keyboard embodied a set of generic commands, which were used in a consistent way
across all applications: Move, Copy, Delete, Open, Show Properties, and Same (copy
properties). Evoking one of these commands produced the same behavior whether the
object is being moved or copied, for example, was a word of text, a drawing element,
or a folder of documents. Through the use of property sheets the user could
manipulate the aspects that were specific to each element, such as the font of a text
character, or the brush width of a painted line. The Open command was the basis for
applying a technique of progressive disclosure—showing the user only the relevant
information for a task at hand, and then providing a way to reveal more possibilities,
as they were needed.
In addition to these three key concepts, many specific design features made the Star
unique, including its attention to the communicative aspects of graphic design, its
integration of an end-user scripting language (CUSP), and its underlying mechanisms
for internationalization—from the very beginning, Star versions were developed in
several languages, including non-European languages with large character sets, non–
left-to-right orthography, and so on.
Some of the aspects that led to the Star's design quality may have also hampered its
commercial success—in particular Xerox's dependence on development groups within
a single company to produce all the applications software.

Lisa by Apple

The GUI (Graphical User Interface) that started it all. If you are sitting in front of a
computer with a mouse and pull down menus you owe it to this machine. Windows
proponents will tell you that Xerox PARC developed GUIs and Apple stole it from
them, therefore what Mr. Gates has done is okay. Xerox had the core idea, but I've
seen video of the early PARC work. It was advanced but it was not nearly what the
Lisa (and later the Mac) became.
The first Apple Lisa was equipped with dual 5.25 inch floppy drives in addition to a
huge external hard drive (shown here). The Apple Lisa 2/10 moved the hard drive
inside the case. It lost one floppy drive and the Macintosh the newer 3.5-inch floppy
shared the remaining one.
My Lisa is the later variety. In fact I have no way of knowing how mine was sold but
the Lisa was later marketed as the Macintosh XL: a bigger sister to the little
Macintosh. Lisa lacked the ROM toolbox built into every Macintosh so it had to do
Macintosh emulation through a new operating system known as MacWorks. It
allowed Lisa to pretend she was a Macintosh. Why do this when you could just buy a

Mac? Lisa offered more RAM (1 meg) a hard drive (10 meg) and some businesses
had already bought them.
While giving credit to the workers at Xerox it should also be mentioned that much of
the groundwork was done in the 1960s and early 1970s. one influential researcher was
Licklider (1960), who visualized a symbiotic relationship between humans and
computers. He envisaged computers that would be able to do more than simply handle
information: the partnership of computer and human brain would greatly enhance
thinking processes and lead to more creative achievements. Another influential
development was the pioneering work of Sutherland (1963), who developed the
Sketchpad system at MIT. The Sketchpad system introduced a number of powerful
new ideas, including the ability to display, manipulate and copy pictures represented
on the screen and the use of new input devices such as the light pen.
Alongside developments in interactive graphic interface, interactive text processing
systems were also evolving at a rapid rate. Following in the footsteps of line and
display editors was the development of systems that allowed users to create and edit
documents that were represented fully on the screen. The underlying philosophy of
these systems is captured by the term WYSIWYG, which stands for ‘what you see is
what you get’ (pronounced ‘whizzee-wig’). In other words, the documents were
displayed on the screen exactly as they would look in printed form. This was in stark
contrast to earlier document editors, where commands were embedded in the text and
it was impossible to see what document would look like without printing it.
Interestingly, difference in research and development interests could be discerned on
the two sides of the Atlantic. Pioneers of HCI in the USA were primarily concerned
with how the computer could enrich our lives and make them easier. They foresaw it
as a tool that could facilitate creativity and problem solving. In Europe, in 1980
researchers began to be more concerned with constructing theories of HCI and
developing methods of design which would ensure that the needs of users and their
tasks were taken into account. One of the major contributions from the European side
was an attempt to formalize more fully the concept of usability and to show how it
could be applied to the design of computer systems (Shackel, 1981).
During the technology explosion of the 1970s the notion of user interface, also known
as the Man-Machine Interface (MMI), became a general concern to both system
designers and researchers. Moran defined this term as ‘those aspects of the system
that the user comes in contact with’ (1981, p.4), which in turn means ‘an input
language for the user, an output language for the machine, and a protocol for
interaction’ (Chi, 1985, p.671).

researchers were concerned about how the use of computer might enrich
the work and personal lives of people. In particular, they focused on the capabilities
and limitations of human users, that is, understanding the ‘people side’ of the
interaction with computer systems. At that time this primarily meant understanding
people’s psychological processes when interacting with computers. However, as the
field began to develop it soon became clear that other aspects impinge on users and
management and organizational issues and health hazards are all important factors
contributing to the success or failure of using the computer systems. [2]


[1] About Face 2.0 the essentials of interaction design by Alan Cooper
[2] Human Computer Interaction by Jenny Preece

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