Lec 2: Introduction to Usability

Introduction to Usability

Recap of Previous Lecture

• The course focuses on the design and implementation of human-computer interfaces, with today's lecture being an introduction to usability.

• A brief recap highlights the basic ideas of interactive systems and concerns in their design, along with a historical overview.

Understanding Usability

• Usability is a critical concept in designing interactive systems; it emphasizes user-centric design.

• The major design challenge for interactive systems will be elaborated from the perspective of a user-centric system designer.

Definition of Human-Computer Interaction (HCI)

• HCI is defined as a discipline focused on the design, evaluation, and implementation of interactive computing systems for human use.

• The definition underscores the importance of incorporating human needs and expectations into system design.

User Differentiation in Design

Importance of User Characterization

• Previous discussions included designing for layman users and understanding their differences from other computer users.

• An example involving railway ticket booking illustrates why differentiating between user types is essential.

User Expectations and Needs

• Users (travelers or agents) are expected to perform fundamental tasks like inputting station names, checking seat availability, booking tickets, and making payments.

• Both travelers/agents and database managers query the same railway database but have different expectations based on their roles.

Task Comparison Between User Types

• While both user types perform similar operations (querying), their purposes differ significantly.

• Travelers focus on obtaining understandable information without needing technical knowledge about database structures or languages.

Designing for Specific Users

• Understanding who the user is crucial for effective interface design; designers must consider varying needs based on user type.

Understanding User Categories in Design

Classification of Users

• The term "user" can be ill-defined; it is essential to categorize users for effective design.

• Users are classified into three broad categories: novice, intermittent, and expert.

• This classification helps in building systems that are more acceptable to specific user groups.

Examples of User Interaction

• A common example involves saving a document in a text editor, which can be done through menu options or keyboard shortcuts.

• Menu options cater to novice users who may not know keyboard shortcuts, while hotkey combinations (e.g., Control + S) are designed for expert users.

Understanding User Types

• Novice users are first-time users unfamiliar with all features; intermittent users use the system occasionally and may forget how to use it effectively.

• Expert users frequently engage with the system but do not necessarily have technical expertise; their expertise lies in using the system efficiently.

Interdisciplinary Approach to Human-Computer Interface Design

Importance of Human Factors

• Designing human-computer interfaces requires understanding human factors and incorporating them into the design process.

• This approach necessitates knowledge from various disciplines including computer science, psychology, design, social sciences, and AI.

Perspectives on User-Centric Design

• Different stakeholders view user-centric design differently: creative designers focus on interface aesthetics, product designers emphasize form and functionality, while electronic engineers consider hardware features.

Application Software Development Perspective

Focus on Application Developers

• The course emphasizes building user-centric software from the perspective of application software developers.

• Developers must follow a lifecycle that considers user characteristics to better meet needs and expectations.

Usability as a Key Concept

• To incorporate user needs into software design effectively, usability serves as an explicit measure for evaluating designs.

Understanding Usability: ISO Standards and Nielsen's Framework

Definition of Usability

• The ISO standard defines usability as the extent to which a product can be used by specified users to achieve specific goals, focusing on effectiveness, efficiency, and satisfaction in a specified context of use.

• The definition emphasizes that usability is not universal; it is tailored for a specific group of users rather than all potential users.

Key Aspects of Usability

• A crucial aspect is that products should allow users to achieve a specific set of goals. Including every conceivable feature does not guarantee usability.

• Another important point is that usability must be designed for a specified context of use, meaning it may not be effective across all scenarios.

Measures of Usability

• The ISO standard mentions three explicit measures: effectiveness, efficiency, and satisfaction. However, Jacob Nielsen argues that usability alone cannot determine if a product is useful.

• According to Nielsen, both usability (ease of use perception) and utility (serving user needs) are necessary for a product to be considered useful.

Nielsen's Quality Components

• Nielsen proposed five quality components for measuring usability:

• Learnability: Ease with which novice users perform basic tasks.

• Efficiency: Speed at which tasks are completed.

• Memorability: Ability of intermittent users to regain proficiency after gaps in usage.

• Additional components include:

• Errors: Rate and severity of errors made by users and ease of recovery from them.

• Satisfaction: Subjective measure reflecting how pleasant the design is to use.

Comparison Between ISO and Nielsen

• While the ISO definition provides two measures (efficiency and satisfaction), Nielsen’s framework offers five measures, suggesting it may provide more precise insights into usability.

• In summary, an effective usable product should cater specifically to defined user groups within particular contexts while achieving designated goals.

Conclusion on Usability Concepts

User-Centered Design: Key Concepts and Definitions

Introduction to User-Centered Design

• The term "user-centered design" was first introduced by Shneiderman in 1986, aiming to enhance product usability.

• This design process involves either active or passive user involvement throughout the development lifecycle.

Types of User Involvement

• Active involvement means users participate directly in the design process, while passive involvement refers to gathering user feedback without direct participation.

• Related concepts include:

• Cooperative Design (Greenbaum & Kyng, 1992)

• Participatory Design (Schuler & Namioka, 1993)

• Contextual Design (Beyer & Holtzblatt, 1997)

Common Terminology and Standards

• Despite minor methodological differences, terms like user-centered design, human-centered design, and participatory design all emphasize user involvement in product development.

• The ISO also recognizes these concepts under its standards for human-centered design.

Summary of Key Takeaways

• User involvement can be both active and passive; collecting input is crucial for effective product development.