HumanComputer Interaction 1-13 Foundations ofHCT

141 Reasoning
.Reasoning is the process by which we use the knowledge we have to draw conclusions or
infer something new about the domain of interest.
Types of reasoning: Deductive, Inductive and Abductive.

1. Deductive reasoning
Deductive reasoning is a basic form of valid reasoning. Deductive reasoning or deduction,
starts out with a general statement, or hypothesis, and examines the possibilities to reach a
specific, logical conclusion.

.Deductive reasoning derives the logically necessary conclusion from the given premises.
For example: "All men are mortal. Harold isa man. Therefore, Harold is mortal."
.Example: When it rains, Rakshita's old car won'tstart. It's raining. Therefore, Rakshita's
old car won't start.

.For deductive reasoning to be sound, the hypothesis must be correct. It is assumed that the
premises, "All men are mortal" and "Harold is a man" are true. Therefore, the conclusion is
logical and true.

In deductive reasoning, if something is true of a class of things in general, it is also true for
all members of that class.

2. Inductive reasoning
.Inductive reasoning is the opposite of deductive reasoning. Inductive reasoning makes
broad generalizations from specific observations. Basically, there is data, then conclusions
are drawn from the data.
Example: Rakshita's old carwon'tstart. It's raining. Therefore Rakshita's old car won't
start when it's raining.
Inductive reasoning involves drawing conclusions from facts, using logic. We draw these
kinds of conclusions all the time. If someone we know to have good literary taste
recommendsa book, we may assume that means we will enjoy the book.
Induction can be strong or weak. If an inductive argument is strong, the truth of the
premise would mean the conclusion is likely. If an inductive argument is weak, the logic
Connecting the premise and conclusion is incorrect.

3. Abductive reasoning:
ne third type of reasoning is abduction. Abduction reasons from a fact to the action or
State that caused it. This is the method we use to derive explanations for the events we
observe.

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 Foundations of HCI
Human Computer Interaction
1-14
nas been
fast when she
O
example, suppose know. that Sam alwavs drives too
we
arinking. If we see Sam driving too fast we mav infer that she has been drinkig

1.4.2 Difference between Deductive and Inductive Reasoning

Deductive reasoning Inductive reasoning

from observation to idea.

Deduction moves from idea to observation Induction moves

Induction moves from more specitic to more

Deduction moves from more general to more
specific. general.

Deductive reasoning is reasoning where true Inductive reasoning is reasoning where the

premises develop a true and valid conclusion premises support the conclusion.
Deduction is more precise and quantitative Induction is more general and qualitative.
If the premises are true, the conclusion is
If the premises are true, the conclusion must be
probably true.
true

1.4.3 Problem Solving

in forrina neTAT information from w7ho+io 1
1.3.6 Interactivity This can be seen in
interactive system.
feature of an
Interactivity is the defining
many areas of HCI.
still inaccurate
interfaces are rapidly improving but
() Speech-driven
e.g. airline reservation:
back its understanding
reliable "yes" and "no" and also system reflects
Boston?"
"you want a ticket from New York to

the same elements: windows, icons.

Menus, pointers,
ii) Look and feel WIMP systems have
behave differently
etc.but different window systems
buttons,
Windows menus
e.g. MacOS vs
appearance + behaviour
=
look and feel

(ii) Initiative
that when a dialog box
The major example is modal dialog boxes. It is often the case
to do anything else until the dialog box
appears the application will not allow you
has been completed or cancelled.

(iv) Error and repair

can't always avoid errors but we can put them right
make it easy to detect errors then the user can repair them

(V) Context
Interaction affected by social and organizational context
other people
desire to impress, competition, fear of failure
 Foundations of HCI 1.25

motivation

fear, allegiance, ambition, self-satisfaction

inadequate systems
cause frustration and lack of motivation

1.3.7 Paradigms
Successful interactive systems are commonly believed to enhance usability and,
therefore, serve as paradigms for the development of future products. They are Predominant
theoretical frameworks or seientihe world views. abew
e.g, Aristotelian, Newtonian, Einsteinian (relativistic) paradigms in physics

Paradigms ofinteraction

New computing technologies arrive, creating a new perception of the

human -computer relationship.
We can trace some of these shifts in the history of interactive technologies.

Example Paradigm Shifts w

Batch processing
Timesharing
Networking teadiviebhow-lporo ol gnitrgonoo gnioalal
Graphical display
Microprocessor goeab outllu to to omgansc sft
www unigg e tteesoony bnoe
Ubiquitous Computing
Time-sharing
1940s and 1950s - explosive technological growth- the significant advances

computing consisted of new hardware technologies

bine-8e
1960s -

need to channel the power

olo oiidieir
The concept oftime sharing is that a single computer supporting multiple users

Video Display Units

more suitable medium than paper
1962-Sutherland's Sketchpad
Computers for visualizing and manipulating data from the computer in the form of
images on a VDU(video display units)
One person's
contribution could drastically change the history of computing
1,26 Humnan Computer Interactlon

Programming toolkits towards rds achievinos

achieving the
in the 1960s worked
Research Institute
Engelbart at Stanford
manifesto set forth in 1963
blocks to produce comnl.
toolkit provides building plex
the right programming
interactive systems

Personal computing programming by children

simple graphics
1970s-Papert's LOGO language for
easier to user
as it becomes
A system is more powerful
machines dedicated to
the individual
Future of computing in small, powerful
Dynabook as the ultimate personal computer
Kay at Xerox PARC-the

Window systems and the WIMP interface

than one task at a time 112gog-pud
humans can pursue more

windows used for dialogue partitioning, to "change the topic" o oW

1981-Xerox Star first commercial windowing systemn
windows, icons, menus and pointers now familiar interaction mechanisms

Metaphor
Relating computing to other real-world activity is effective teaching technique
LOGO's turtle dragging its tail
file management on office desktop
an
p5ooooiM
word processing as typing www
financial analysis on spreadsheets
nugnoeoaupid
virtual reality user inside the
metaphor
-

-
Direct manipulation

1982-Shneiderman describes appeal of

visibility of objects
graphically-based interaction
incremental action and rapid
feedback
reversibility encourages exploration
syntactic correctness of all actions
replace language with action
1984-Apple Macintosh
the model-world metaphor
.What You See Is What You
Get
(WYSIWYG) eeoeen
 Foundations of HCI 1.27

Language versus Action

actions do not always speak louder than words!

DM- interface replaces underlying system

language paradigm
interface as mediator T
interface acts as intelligent agent
programming by example is both action and language

Hypertext
In mid 1960s - Nelson deseribes hypertext as non-linear browsing structure

hypermedia (or multimedia) is used for non-linear storage of all forms of electronic
media.

Multimodality
a mode is a human communication channel
emphasis on simultaneous use of multiple channels for input and output

Work (CSCW)
Computer Supported Cooperative
CSCW removes bias of single user/ single computer system
Can no longer neglect the social aspects

Electronic mail is most prominent success

The World Wide Web

Hypertext, as originally realized, was a closed system
Simple, universal protocols (e.g. HTTP) and mark-up languages (e.g. HTML) made
publishing and accessing easy
Critical mass of users leads to a complete transformation of our information economy.

Agent-based Interfaces
Original interfaces
Commands given to computer
Language-based
Direct Manipulation/WIMP
'Commands performed on "world" representation
Action based
Agents-return to language by instilling proactively and "intelligence" in command
processor
1.28 Human Conputer Interaction

Avatars, natural language processing

Ubiguitous Computing Mo
are those that disappear."
The
Th me profound technologies
e most

Mark Weiser, 1991

oeibernsanhotoi
Late 1980's: computer was very apparent

How to make it disappear?

Shrink and embed/distribute it in the physical world
demand our intention
Design interactions that don't
Sensor-based and Context-aware Interaction
situation and reacting appropriatelv
Humans are good at recognizing the "context" ofa

Automatically sensing physical phenomena (e.g., light, temp, location, identitv

becoming easier
1.7 Interaction Models
There are at least two participants required for interaction. Here we consider user and

system are the two participants. The interface must therefore effectively translate between
them to allow the interaction to be successful.

The purpose of an interactive system is to help a user in accomplishing goals from some
application domain. A domain defines an area of expertise and knowledge in some rea
world activity.
Domain example are graphic design, authoring and process control in a factory. A domain
consists of concepts that highlight its important aspects.

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 Human Computer Interaction 1-23 Foundations of HCI

o Tasks are operations to manipulate the concepts of a domain. A goal is the desired

output from a performed task.

o An interaction model is a design model that binds an application together in a way that

supports the conceptual models of its target users.

o It enables designers, developers, and stakeholders to understand and explain how users
move from objects to actions within a system.

1.7.1 The Execution-Evaluation Cycle

.Phases of an interactive cycle are: Execution and Evaluation.
goal
execution evaluation

system

. Norman's s model ofinteraction are as follows:

1. User establishes the goal 2. Formulates intention

3. Specifies actions at interface 4. Executes action

5. Perceives system state 6. Interprets system state

7. Evaluates system state with respect to goal

Stage 1 is Forming a Goal. This is what you want. As an example, I might want a place that I

can relax outside that won't get muddy and that I don't have to move my outdoor furniture
around to mow.
Stage 2 is Forming the Intention. This is what would satisfy the goal. A deck would satisfy my
goal of place to relax outdoors that won't get muddy or be in the way of mowing.

Stage 3 is Specifying an Action. What do I have to do to achieve the intention ? I would need
to build a deck to meet the requirements set in my goals.

Stage 4 is Executing the Action. Here I would do the steps of the action. I would build the
deck
Stage 5 is Perceiving the State of the World. Using the senses to gather information. My
finished deck would be off the ground and have my outdoor furniture on it.
Stage 6 is Interpreting the State of the World. What has changed ? My fürniture is off the

8round away from the mud and no longer has to be moved to mow the lawn.
otage 7 is Evaluating the Outcome. Did I achieve my goal ? I can relax outdoors now witnout

Worrying about mud or moving furniture. I achieved my goal

4. Explain the various models and frameworks of Interaction
Interaction involves at least two participants- the user and the system.
The interface must effectively translate between them to allow the interaction to be successful. This
translation can fail at a number of points and for a number of reasons. The use of models of
interaction can help us to understand exactly what is going on in the interaction and identify the likely
root of difficulties.
1.Norman's execution-evaluation cvcle
The terms of interaction
Traditionally, the purpose of an interactive system is to aid a user in accomplishing goals
from some application domain.
 in some real-world activity. A domot
A domain defines of expertise and knowledge
an area main
consists of concepts that highlight its important aspects.
Tasks are operations to manipulate the concepts of a domain. A goal is the desired output
from a performed task.
An intention is a specific action required to meet the goal. Task analysis involves the
identification of the problem space for the user of an interactive system in terms of the domain, goals,
intentions and tasks. The concepts used in the design of the system and the description of the user are
Separate, and so we can refer to them as distinct components, called the System and the User,
respectively.
The System and User are each described by means of a
language that can express concepts
relevant in the domain of the application. The System's
language we will refer to as the core language
and the User's language.
The language describes computational attributes of the domain relevant to the System
core

state, whereas the task language describes psychological attributes of the

domain relevant to the User
state.

2. The executionevaluation cycle

Norman's model of interaction is perhaps the most
influential in
possibly because of its closeness to our intuitive understanding of the Human-Computer
Interaction,
and computer. The user formulates a interaction between human user
plan of action, which is then executed at the interface.
When the plan, or part of the
plan, has been executed, the user observes the computerinterface to
evaluate the result of the executed plan, and to computer
determine further actions. The interactive
divided into two major phases: execution and
evaluation,
cycle can be
 ought 2. Doing too mai

2 People confuse two similar tasks 3. Time pressures.

1.7.4 Interactlon Framework

the system
hteraction: Ommunication between the user and
acuviy
knowledge in real-world
Domain: Area of expertise and

aSSOPerations to manipulate the concepts of a

domain

Goal: Desired output from

performed a

Intention: Specific action required to meet goal.

of the domain, goals
for the user in terms
Tas Analysis : Identification of problem space

intentions and tasks.

Fig. 1.7.1 shows general interaction framework.
nteraction framework has 4 parts: User, Input, System and Output

presentation observation output

Output

U
core task task

performance I articulaton I
nput nput

Fig. 1.7.1(a) General interaction framev Fig. 1.7.1(b) Translation between components
Each has its own unique language. Interaction necessitates translation between languages
Problems in interaction occur when translation between one
language and the next
difficult, or impossible.
1. User intentions translated into actions at the interface.
2. Translated into alterations of system state,
3. Which in turn are reflected in the
output display ?
4. Which is
interpreted by the user?
.Some systems are harder to use
than others
Gulf of Execution User's-

formulation of actions
by the system may be different to
allowe
those actions a

Gulf of Evaluation User's expectation of the

-

changed system state may be tothe

differel
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 Human Computer Interaction Foundations of HCI
1-27

actual presentation of this state.

Fig. 1.7.2 shows Framework for human computer interaction adapted from ACM SIGCHI
curriculum development group.
Dialog design and interface styles can be placed particularly along the input branch of the
framework, addressing both articulation and performance.
Presentaticon and screen design relate to the output branch of the framework.
The entire framework can be placed within a social and organizational context that also
affects the interaction. Each of these areas has important implications for the design of
interactive systems and the performance of the user.
ed000000000000000o

Soc:al and organizational conext

Screen
design
Ergonomics
wwwNe

Dialog
w w d i v w w w a
2.2 HCI IN SOFTWARE PROCESS
2.2.1 The Software Life Cycle: design pioes
the software
Is the discipline for understanding
gneering
or life cycle
of the life cycle, not as sin
a
Designing for usability occurs at all stages
activity
matter or aduing
for interactive system design is not simply a
SOTtware engineering
life cycle.
activities in the
one more activity that slots in nicely with the existing

Rather, it involves techniques that span the entire life cycle

Phases of software life cycle:

Requirement specification
Architectural Design

Detailed Design
Unit testing bwrod
Coding and
Integration and testing

Operation and Maintenance l swp

 Requirements booltang
specification

Architectural
design
Detailed onn uo boandg 2bubong
design
Coding and
unittesting
Integration
andtesting
Operation and
maintenance

Figure: 2.1ll The activities in the waterfall model of the software life eycle

Requirements specification:
Designer and customer try capture what the system is expected to provide can be
expressed in natural language or more precise languages, such as a task analysis would provide.

Architectural design:
High-level description of how the system will provide the services required factor
system into major components of the system and how they are interrelated needs to satisfy both
functional and non-functional requirements
Present functionality through a familiar metaphor.
Provide similar execution style of analogous operations in different applications.
of a system to support common user tasks.
Organize the functionality
Make invisible parts and processes visible to the user.

Detailed design:
Refinement of architectural components and interrelations to identify modules to be
implemented separately the refinement is governed by the non-functional requirements

Coding and Unit Testing:

Ihedetailed design for a component of the system should be in such a form that it
Spossible to implement it in some executable programming language. After coding, the
Component can be tested to verify that it performs correctly, according to some test criteria that
were determined in earlier activities u ta t 1. t
2.12 Human Conputer Interaction

Integration and testing

Testing is done to ensure correct behavior and acceptable use of any shared resources,

Maintenance
After product release, all work on the system is considered under the category of
maintenance, until such time as a new version of the product demands a total redesign or the
product is phased out entirely

Validation and Verification

Verification
Designing the product right

Validatio
Designing the right product

Real-world
requirements
and constraints
The formality gap

Figure 2.12 The formality gap between the real

world and structure d
design
The formality gap: Validation will always rely to some extent on
proof. subjective means of

Requirements
analysis

Architectural
specification

Detailed
specification

Implementation
and unit
testing

Integracion etyebatnoe
and cesting

Operation and
maintenance
Figure: 2.13 Feedback from maintenance activity to olaldieog
other design activities
 Design & Software Process 2.13

Interactive systems and the software life cycle oos8 ban suddh
The actual design process is iterative, work in one design activity affecting work in any
other activity both before and after it in the life cycle.
boem goneeebM
Requirements
specification
ovsl wolf
Architectural
design
lovol bonnolf
Detailed
design O

Implementation e 021 boobeste oid

and unit
testing

onevioolo
Integration
and testing

Operation and
holo anbesw Juordie maintenance

Figure: 2.14 Representing iteration in the waterfall model

2.2.2 Usability Engineering