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What is HCI?What is HCI?Goal of HCIGoal of HCIHCI - An Interdisciplinary AreaHCI - An Interdisciplinary AreaConcerns in HCIConcerns in HCIInterface and interaction designInterface and interaction designGoals of interaction designGoals of interaction designUtility, Usability, LikeabilityUtility, Usability, LikeabilityStructured Process for Creating Usable ProductsStructured Process for Creating Usable ProductsPrinciples to support usabilityPrinciples to support usabilityHow to Achieve UsabilityHow to Achieve Usability

Human–computer Interaction (HCI) involves the study, planning, and design of the interaction between people (users) and computers. Interaction between users and computers occurs at the user interface (or simply interface), which includes both software and hardware.

Human Computer Interaction (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”

Human Computer Interaction (HCI)

Because human–computer interaction studies a human and a machine in conjunction, it draws from supporting knowledge on both the machine and the human side.

On the machine side, techniques in computer graphics, operating systems, programming languages, and development environments are relevant.

On the human side, communication theory, graphic and industrial design disciplines, linguistics, social sciences, cognitive psychology, and human factors such as computer user satisfaction are relevant.

Goal of HCIA basic goal of HCI is to improve the interactions between users

and computers by making computers more usable and receptive to the user's needs. Specifically, HCI is concerned with:

Methodologies and processes for designing interfaces (i.e., given a task and a class of users, design the best possible interface within given constraints, optimizing for a desired property such as learnability or efficiency of use). Methods for implementing interfaces (e.g. software toolkits and libraries; efficient algorithms). Techniques for evaluating and comparing interfaces. Developing new interfaces and interaction techniques. Developing descriptive and predictive models and theories of interaction.

The Goals of HCI

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To Produce

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In order to produce computer system with good usability;In order to produce computer system with good usability;Developers must attempt to Developers must attempt to

The long term goal:The long term goal:To design systems that minimize the barrier between the To design systems that minimize the barrier between the

human’s cognitive model of what they want to accomplish and human’s cognitive model of what they want to accomplish and the computer’s understanding of the user’s taskthe computer’s understanding of the user’s task

HCI - An Interdisciplinary Area/Disciplines that Contribute to HCI

Computer ScienceApplication design and engineering of human-computerInterfaces PsychologyThe application of theories of cognitive processes andthe empirical analysis of user behavior Sociology and AnthropologyInteractions between technology, work, and organization Design and Industrial DesignCreating interactive products

Concerns in HCIScience, Engineering, and Design Aspects

The joint performance of tasks by humans and machines The structure of communication between human andmachine Human capabilities to use machines (including thelearn ability of interfaces) Algorithms and programming of the interface itself Engineering concerns that arise in designing andbuilding interfaces The process of specification, design, and implementationof interfaces

Interface and interaction design

Interface design (ID)• Primarily design of 2D/3D widgets

Designing interactive products to support people in their everyday and working lives

• Sharp, Rogers and Preece (2002) The design of spaces for human communication and interaction

• Winograd (1997)

Goals of interaction design

Develop usable productsUsability means:

• easy to learn• effective to use• enjoyable experience

Usable products = successful products?

Involve users in the design process

Utility, Usability, Likeability

Utilitya product can be used to reach a certain goal or toperform a certain task. This is essential! Usabilityrelates to the question of quality and efficiency. E.g. howwell does a product support the user to reach a certaingoal or to perform a certain task. Likeabilitythis may be related to utility and usability but notnecessarily. People may like a product for any otherreason…

What is Usability

“Usability is a quality attribute that assesses how easy user interfaces are to use. The word ‘usability’ also refers to methods for improving ease-of-use during the design process.”

Usability has five quality components: Learn ability: How easy is it for users to accomplish basic tasks

the first time they encounter the design?Efficiency: Once users have learned the design, how quickly

can they perform tasks? Memorability: When users return to the design after a period of

not using it, how easily can they reestablish proficiency? Errors: How many errors do users make, how severe are these

errors, and how easily can they recover from the errors? Satisfaction: How pleasant is it to use the design?

USABILITY

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Why is Usability Important

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Why Usability is Important?

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How many systems are

easy, effortless, and enjoyable

to use?

Improving usability can• increase productivity of users• reduce costs (support, efficiency)• increase sales/revenue (web shop)• enhance customer loyalty• win new customers

Why is Usability Important?

Why is Usability Important in theContext of WWW and New Media?

Competition is very close (just another link…) User Interface is often the central discriminating factor Comparison is easily possible

Example – Online-ShopDirect correlation between usability and sales is reported in many cases.Users who can’t find the product in the shop can not buy it.Users who are not able to fill in correctly the order form are not going to buy.

HCI is Central to the Design and Development Process

… even if done unconsciously. Decisions madein the development process are likely to influence how a product can be used.

thinking about the user interface when a firstversion of a product is finished is to late!

good user interfaces – and often good products– are a joined effort of all participants in thedesign and development process

Structured Process for Creating Usable Products

Precondition• Understanding how people interact with their environment• Understanding the capabilities and limitations of users• Basic ergonomics

Analyze what interaction is required and what technicaloptions are available in a user centered way, evaluatethe results of the analysis

Design and prototype user interfaces with userinvolvement, evaluate prototypes Implement an interactive digital product Test and study the product created Usability Engineering is a part of the overall development The process is iterative (overall and at each step)

Evolution of the Software Development Process

How it does NOT work Usability tests at the end when the product isready and needs to be shipped.

Designing a new and pretty skin to a product.

Introducing HCI issues after the systemarchitecture and the foundations are completed.

Comparison: An interior designer can not makea great house if the architect and engineers forgot windows, set the doors at the wrong locations, and created an unsuitable room layout.

Principles to support usability

Learnabilitythe ease with which new users can begin effective interaction and achieve maximal performance

Flexibilitythe multiplicity of ways the user and system exchange information

Robustnessthe level of support provided the user in determining successful achievement and assessment of goal-directed behaviour

Principles of learnability

Predictability– determining effect of future actions based on

past interaction history– operation visibility

Synthesizability– assessing the effect of past actions– immediate vs. eventual honesty

Principles of learnability (ctd)Familiarity

– how prior knowledge applies to new system– guessability; affordance

Generalizability– extending specific interaction knowledge to new

situations

Consistency– likeness in input/output behaviour arising from similar

situations or task objectives

Principles of flexibility

Dialogue initiative– freedom from system imposed constraints on input

dialogue– system vs. user pre-emptiveness

Multithreading– ability of system to support user interaction for more

than one task at a time– concurrent vs. interleaving; multimodality

Task migratability– passing responsibility for task execution between user

and system

Principles of flexibility (ctd)

Substitutivity– allowing equivalent values of input and

output to be substituted for each other– representation multiplicity; equal opportunity

Customizability– modifiability of the user interface by user

(adaptability) or system (adaptivity)

Principles of robustness

Observability– ability of user to evaluate the internal state of the

system from its perceivable representation– browsability; defaults; reachability; persistence;

operation visibility

Recoverability– ability of user to take corrective action once an error

has been recognized– reachability; forward/backward recovery;

commensurate effort

Principles of robustness (ctd)

Responsiveness– how the user perceives the rate of

communication with the system– Stability

Task conformance– degree to which system services support all

of the user's tasks– task completeness; task adequacy

How to Achieve Usability

Identify what utility and usability for the product means• main purpose of the product• anticipated users, target audience• compare with similar/competing products (if applicable)

Common effort in the design and development process • trade-offs between design, engineering, and usability Iterative evaluation • usability testing with different methods at various stages of the development process Improvement after product release

• monitoring user behavior.• evaluation of changes to the product (e.g. adding a new featureto a web shop)

Design principles

When evaluating a current user interface, or designing a new user interface, it is important to keep in mind the following experimental design principles:

Early focus on user(s) and task(s): Establish how many users are needed to perform the task(s) and determine who the appropriate users should be; someone who has never used the interface, and will not use the interface in the future, is most likely not a valid user. In addition, define the task(s) the users will be performing and how often the task(s) need to be performed.

Empirical measurement: Test the interface early on with real users who come in contact with the interface on an everyday basis. Keep in mind that results may be altered if the performance level of the user is not an accurate depiction of the real human-computer interaction. Establish quantitative usability specifics such as: the number of users performing the task(s), the time to complete the task(s), and the number of errors made during the task(s).

Iterative design: After determining the users, tasks, and empirical measurements to include, perform the following iterative design steps:

1. Design the user interface2. Test3. Analyze results4. Repeat

Repeat the iterative design process until a sensible, user-friendly interface is created

Design methodologies