Unit 3: HCI Models and Theories

User Profiles

In human-computer interaction (HCI), user profiles represent the characteristics of users that influence their interaction with systems. User profiles help designers create systems that cater to the needs, preferences, and limitations of different users. A user profile typically includes information such as:

• Demographics: Age, gender, educational background, occupation.
• Technical skills: Computer literacy, familiarity with specific tools or software.
• Cognitive abilities: Memory capacity, problem-solving skills, and decision-making processes.
• Preferences: Personalization preferences, interface layout, or color schemes.
• Context of use: When, where, and why users interact with a system, including environmental factors like lighting, device type, or distractions.

Importance of User Profiles

• Helps in user-centered design, ensuring that the system meets the needs of the target audience.
• Facilitates customization and personalization of interfaces, improving user satisfaction.
• Assists in identifying accessibility requirements for users with disabilities or other challenges.
• Aids in usability testing by focusing on specific user groups and their unique needs.

Categorization of Users

Users can be categorized into different types based on their interaction styles, goals, or abilities. Categorizing users is essential for designing systems that are intuitive and functional across a broad range of user groups. The main categories include:

1. Novice Users:

   • Have little to no experience with the system or similar technologies.
   • Require simple, intuitive interfaces with guidance and feedback.
   • Tend to rely on tutorials, help sections, and documentation.

2. Intermediate Users:

   • Have some experience and are familiar with basic functionalities.
   • Expect faster workflows, may use shortcuts or customized settings.
   • Require a balance between ease of use and functionality.

3. Expert Users:

   • Have extensive experience and knowledge of the system.
   • Prefer advanced features and are highly efficient in navigating the interface.
   • Tend to customize interfaces and use command-line interfaces for complex tasks.

4. Disabled Users:

   • May have physical, sensory, or cognitive impairments that affect their ability to interact with traditional interfaces.
   • Need accessible designs, such as screen readers, alternative input devices, or voice commands.

5. Casual Users:

   • Use the system infrequently, with minimal interaction.
   • Require a low learning curve and a simple, straightforward interface.

Goal and Task Hierarchy Model

The Goal and Task Hierarchy Model breaks down user interactions with a system into goals and the tasks required to achieve those goals. This model helps in understanding user behavior and designing systems that support users in completing their tasks.

• Goals: High-level objectives that users want to accomplish (e.g., sending an email).
• Tasks: Specific actions that users take to achieve their goals (e.g., opening the email application, typing the message, pressing send).
• Subtasks: Smaller steps within a task that contribute to the goal.

Importance in HCI

• Helps identify task flow and optimize it for efficiency.
• Ensures that systems support user goals, rather than just focusing on features.
• Provides a framework for task analysis and system design.

Linguistic Model

The Linguistic Model in HCI is concerned with the language and structure used by users to interact with a system. It focuses on the commands, syntax, and semantics users employ when navigating or providing input to a system. This model helps in designing interfaces that are easy to understand and use, especially when the interaction involves text input, voice commands, or any form of language.

Key Aspects:

• Syntax: The rules and structure of commands or input, ensuring that the system can interpret user actions accurately.
• Semantics: The meaning behind user input and commands, ensuring that the system responds appropriately.
• Grammar: How users form sentences or commands to interact with the system, similar to linguistic grammar in spoken language.

Application in HCI:

• Used to design voice interfaces, text-based search engines, or chatbots.
• Important for systems involving natural language processing (NLP) or multimodal interaction.

Physical and Device Models

Physical and device models focus on the relationship between human physiology and the devices used to interact with a system. These models take into account:

• Physical capabilities: The range of motion, dexterity, and strength required to use input devices like keyboards, mice, or touchscreens.
• Device constraints: Limitations of the hardware, such as screen size, input precision, and responsiveness.

Key Considerations:

• Ergonomics: The design of devices to fit human body mechanics, minimizing strain and maximizing comfort.
• Accessibility: Designing for users with disabilities, ensuring that input/output devices accommodate diverse needs (e.g., alternative input methods for motor-impaired users).

GOMS Model

GOMS (Goals, Operators, Methods, and Selection rules) is a predictive model used to evaluate user performance and system usability. It breaks down tasks into component steps and provides a way to estimate how long each step will take, allowing designers to predict overall task efficiency.

• Goals: The user's objectives (e.g., printing a document).
• Operators: Basic actions performed to achieve the goal (e.g., clicking a button, typing).
• Methods: The different ways a user can accomplish the goal (e.g., using a shortcut or menu option).
• Selection rules: Guidelines for choosing between methods based on the context.

Importance:

• Helps designers evaluate task efficiency and predict user behavior.
• Useful for optimizing user interfaces by identifying unnecessary steps or complex workflows.

Norman's 7-Stage Model

Donald Norman’s 7-stage model of interaction outlines the process users go through when interacting with a system. It emphasizes the importance of feedback and user-centered design.

The stages include:

1. Forming the goal: The user identifies what they want to achieve.
2. Forming the intention: The user decides how to achieve the goal.
3. Specifying the action: The user identifies the specific actions required.
4. Executing the action: The user performs the actions.
5. Perceiving the system state: The user observes the system’s response.
6. Interpreting the system state: The user makes sense of the system's response.
7. Evaluating the outcome: The user compares the result with the original goal.

Application:

• Ensures that systems provide clear feedback at each stage.
• Helps designers identify potential points of failure where users may struggle or encounter confusion.

Cognitive Architectures

Cognitive architectures are models that represent the structure of human cognitive processes, which help in simulating and predicting human behavior in complex tasks. These architectures help in designing systems that align with how users think and process information.

• ACT-R: A widely used cognitive architecture that focuses on memory, problem-solving, and learning processes.
• Soar: A cognitive architecture that models decision-making and learning in real-time environments.

Use in HCI:

• Cognitive architectures guide the design of systems that work with human cognitive limitations, such as memory and attention.
• Helps in predicting user performance and error rates.

Hierarchical Task Analysis (HTA)

Hierarchical Task Analysis (HTA) is a method used to break down complex tasks into smaller, more manageable subtasks. It involves creating a hierarchical structure where higher-level goals are divided into lower-level tasks and subtasks.

Steps in HTA:

1. Define the overall goal of the task.
2. Break down the task into subtasks and represent them hierarchically.
3. Analyze the relationships between tasks to identify dependencies and task sequences.

Importance in HCI:

• Helps designers understand how users approach tasks and optimize interfaces for efficiency.
• Useful in identifying bottlenecks or unnecessary steps in a workflow.

Uses of Task Analysis

Task analysis is essential in HCI for understanding how users interact with a system and identifying areas for improvement. Some of its uses include:

• System design: Helps in designing systems that align with user needs and workflows.
• Usability testing: Provides a framework for evaluating how easily users can accomplish tasks.
• Training and documentation: Assists in creating user manuals and training programs by highlighting critical steps in a task.
• Error prevention: Identifies potential points of failure in user tasks and helps in designing solutions to mitigate errors.

Diagrammatic Dialog Design Notations

Diagram

matic notations, such as flowcharts and state diagrams, are used to represent the flow of interaction between the user and the system. These notations help in visualizing and designing dialogues, ensuring a smooth and intuitive user experience.

Examples:

• State diagrams: Represent the states the system can be in and the transitions between those states based on user actions.
• Flowcharts: Show the sequence of actions and decisions that the user makes when interacting with the system.

Importance:

• Helps designers visualize complex interactions and ensure that systems respond appropriately to user inputs.
• Aids in identifying potential loops, errors, or inefficiencies in the interaction flow.