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HCI Overview Week 44 - Understanding People 2 Activity Theory

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By Wei Xiong
18 min read
HCI Overview Week 44 - Understanding People 2 Activity Theory

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1. What Is Activity Theory?

Activity Theory is a framework for understanding human activity as a social and developmental process. It emphasizes that human actions are not isolated but are influenced by the social context, tools, and motivations behind them. Activity Theory views activities as complex systems where various components interact to achieve specific objectives.

Fundamental Theses of Activity Theory:

  1. Consciousness is Constructed: Our awareness and understanding develop through our daily activities.
  2. Inherently Social: Human consciousness and activities are shaped by social interactions and cultural contexts.
  3. Mediated by Tools: Tools, both physical and conceptual, mediate our interactions with the world, influencing how we perceive and act.

Key Components:

  • Subject: The individual or group performing the activity.
  • Object: The goal or motivation behind the activity.
  • Tools/Artifacts: Means used to perform the activity, including physical tools and symbolic systems like language.
  • Community: The social context or group involved in the activity.
  • Rules: Norms, laws, and conventions governing the activity.
  • Division of Labor: Distribution of tasks among participants.

2. Why Was Activity Theory Brought into HCI?

Activity Theory was introduced into HCI to address the limitations of traditional, micro-level HCI approaches that focus solely on the individual user’s interaction with a single computer or application. The reasons include:

  • Holistic Understanding: To gain a deeper understanding of how computers influence human development and social contexts.
  • Complex Interactions: To analyze interactions that involve multiple users, devices, and applications within organizational and societal frameworks.
  • Societal Impact: To comprehend how technology shapes and is shaped by societal and organizational changes, thereby affecting broader aspects of life and work.

Example from Lecture Notes:

  • CCLSurgical System: Designing a system for surgical wards required understanding the organizational context, workflow integration, and user competencies, which are aspects well-addressed by Activity Theory.

3. What Does Activity Theory Provide Means to Explain?

Activity Theory offers a comprehensive framework to explain:

  • Human Activities as Systems: Viewing activities as interconnected systems with multiple components (subject, object, tools, community, rules, division of labor).
  • Mediation by Tools: How tools (both physical and symbolic) mediate interactions and influence the way activities are performed.
  • Social and Cultural Influences: The impact of social interactions and cultural contexts on human activities.
  • Development Through Contradictions: How inherent conflicts within an activity system drive its development and evolution.

Application Example:

  • Mobile Pay Systems: Activity Theory helps explain how introducing mobile payment tools alters existing payment practices, user behaviors, and organizational workflows by mediating interactions between users and the payment environment.

4. What Are the Fundamental Principles of Activity Theory?

The fundamental principles of Activity Theory are encapsulated in its three main theses:

  1. Consciousness is Constructed:
    • Human consciousness and understanding develop through engagement in daily activities.
  2. Inherently Social:
    • Activities are shaped by social interactions, cultural norms, and community practices.
  3. Mediated by Tools:
    • Tools, both physical (e.g., computers, pens) and conceptual (e.g., language, symbols), mediate human interactions with the environment and influence how activities are performed.

Additional Principles:

  • Object-Orientedness: All human activities are directed toward an object, which can be a physical item, a goal, or a social construct.
  • Hierarchy of Activity: Activities are structured hierarchically into levels such as activity, action, and operation.
  • Development Driven by Contradictions: Internal conflicts within activity systems drive their development and transformation.

5. Explain the Hierarchical Structure of Activity

Activity Theory organizes human activities into a hierarchical structure consisting of three levels:

  1. Activity (Why?):
    • Definition: The highest level of analysis, representing the overall purpose or motivation behind actions.
    • Characteristics:
      • Motivated by needs.
      • Directed toward objects (goals).
      • Involves constant development.
      • Mediated by tools.
    • Example: Learning a foreign language motivated by career advancement.
  2. Action (What?):
    • Definition: The middle level, representing conscious processes directed toward specific goals.
    • Characteristics:
      • Goal-driven and intentional.
    • Example: Attending language classes, memorizing vocabulary, practicing speaking.
  3. Operation (How?):
    • Definition: The lowest level, representing automatic routines or skills, often unconscious.
    • Characteristics:
      • Automatic and routine-based.
    • Example: Adjusting the volume on headphones without conscious thought, typing on a keyboard efficiently.

Dynamics Between Levels:

  • Automatization: Through practice, actions become operations (e.g., learning to drive a car transforms from conscious steering to automatic control).
  • Conceptualization: When issues arise, operations can become actions as conscious problem-solving is required (e.g., if a car’s GPS fails, the driver must consciously navigate).

6. Explain the Concept of Mediation

Mediation in Activity Theory refers to the role of tools in shaping and facilitating human activities. Tools can be physical artifacts (e.g., computers, smartphones) or symbolic systems (e.g., language, mathematical notation).

Key Aspects of Mediation:

  • Transforming Interactions: Tools mediate the way humans interact with the environment and each other, influencing perception, cognition, and action.
  • Bidirectional Influence: While tools shape human activities, human actions and needs also influence the design and evolution of tools.
  • Types of Tools:
    • Physical Tools: Tangible objects used to perform tasks (e.g., a surgical system in a hospital).
    • Conceptual Tools: Abstract systems like language, symbols, and rules that facilitate thinking and communication.

Examples from Lecture Notes:

  • GitHub Copilot: Acts as a programming assistant, changing how developers write code by mediating their interaction with programming languages and tools.
  • Social Media Platforms: Mediate communication and information sharing, influencing how users interact and perceive social connections.

7. Explain the Principles of Internalisation and Externalisation

Internalisation and Externalisation are foundational processes in Activity Theory that describe how individuals and groups transform knowledge and actions between the internal (mental) and external (environmental) realms.

Internalisation:

  • Definition: The process by which external activities and tools become part of an individual’s internal mental processes.
  • Mechanism:
    • External Actions to Mental Processes: Users adopt tools and practices from their environment, integrating them into their own cognitive framework.
    • Example: Learning to use a smartphone app until it becomes second nature, allowing seamless interaction without conscious effort.

Externalisation:

  • Definition: The process by which internal thoughts and ideas are expressed or manifested in the external environment.
  • Mechanism:
    • Mental Processes to External Actions: Users translate their thoughts and intentions into tangible actions or artifacts.
    • Example: Writing notes to remember tasks, thereby externalizing memory to reduce cognitive load.

Role in Cognition:

  • Foundation of Human Cognition: These processes enable the transformation of mental representations into actions and vice versa, facilitating learning, problem-solving, and adaptation.
  • Development Through Interaction: Continuous internalisation and externalisation drive the evolution of both individual cognition and the development of tools and practices within a community.

Example from Lecture Notes:

  • Learning a Foreign Language:
    • Externalization: Using physical actions like gesturing or writing to understand and practice language concepts.
    • Internalisation: Transforming these external practices into internal language proficiency and cognitive understanding.

8. All Development According to Activity Is Driven by Contradictions

Development within Activity Theory is propelled by contradictions—inherent conflicts or inconsistencies within an activity system. These contradictions create breakdowns that necessitate changes and adaptations, leading to the evolution of activities and the tools used.

Key Points:

  • Constant Development: Human activities, tools, and consciousness are in a state of continuous evolution.
  • Contradictions as Catalysts:
    • Inherent Conflicts: Opposing elements within the activity system (e.g., tool capabilities vs. user needs).
    • Breakdowns: Problems or inefficiencies that arise from these contradictions.
    • Response to Contradictions: Users and communities modify tools, rules, or practices to resolve contradictions, driving development and improvement.

Example from Lecture Notes:

  • Mobile Pay Systems:
    • Primary Contradiction: Choosing between using cash or digital payment methods.
    • Response: Developing more advanced mobile payment features to resolve the limitations and enhance user experience.

9. Explain What a Contradiction Is

In Activity Theory, a contradiction refers to opposing elements or inconsistencies within an activity system that create tensions and problems. These contradictions are not merely obstacles but are seen as the drivers of development and change within the system.

Characteristics of Contradictions:

  • Internal Conflicts: Discrepancies between different components of the activity system (e.g., tools vs. goals).
  • Emerging Issues: Problems that arise when elements of the system do not align or support each other effectively.
  • Catalysts for Change: Contradictions prompt users and designers to adapt, innovate, and evolve tools and practices to resolve the inconsistencies.

Examples from Lecture Notes:

  • Corkscrews:
    • Winged Corkscrew vs. Sommelier’s Corkscrew:
      • Primary Contradiction: Ease of use (winged) vs. professional appearance and skill requirement (sommelier’s).
      • Response: Designing corkscrews that balance ease of use with aesthetic and functional sophistication.

Implications for HCI:

  • Design Iteration: Identifying and addressing contradictions leads to iterative improvements in interface design.
  • User-Centered Development: Understanding contradictions helps in creating tools and systems that better align with user needs and contexts.

Summary of Key Points on Activity Theory in HCI

Activity Theory provides a macro-level framework for understanding complex human activities within their social and cultural contexts. It emphasizes the interaction between individuals and tools, and how contradictions within activity systems drive development and innovation. Key insights include:

  • Hierarchical Structure: Activities are organized into levels of activity, action, and operation, each with distinct characteristics and dynamics.
  • Mediation by Tools: Tools play a crucial role in shaping how activities are performed and how users interact with technology.
  • Internalisation and Externalisation: These processes facilitate the transformation of knowledge and actions between internal mental states and external environments.
  • Contradictions as Drivers: Inherent conflicts within activity systems lead to breakdowns that necessitate adaptations, fostering development and improvement.

Applications in HCI:

  • Design Analysis: Using Activity Theory to analyze user interactions within broader organizational and social contexts.
  • System Design: Creating interfaces that consider user motivations, goals, and the tools that mediate their activities.
  • Addressing Contradictions: Identifying and resolving inconsistencies within activity systems to enhance usability and effectiveness.

By integrating Activity Theory into HCI practices, designers and researchers can achieve a more comprehensive understanding of user interactions, leading to the creation of more effective, contextually relevant, and user-centered technologies. 1. What does it mean to be human-centered?

Being human-centered means designing software and systems with a focus on the users’ needs, abilities, and limitations. It involves making design choices justified by how people actually feel, think, behave, and function. The goal is to create interfaces that are intuitive, efficient, and satisfying for users by understanding and prioritizing their experiences.

2. What is perception and why is it relevant for HCI?

Perception is the process by which individuals receive, interpret, and make sense of sensory information from the environment. In HCI, perception is crucial because it affects how users interact with interfaces. Understanding perception helps designers create user interfaces that align with human sensory capabilities, making information easier to understand and actions more intuitive.

3. What does the human sensor system consist of?

The human sensor system comprises several senses:

  • Vision: Detecting light and color through the eyes.
  • Hearing: Detecting sound waves through the ears.
  • Touch (Tactile perception): Sensing pressure, temperature, and texture through the skin.
  • Smell and Taste: Detecting chemical stimuli through the nose and tongue (less commonly used in HCI).

In HCI, the primary focus is on vision, hearing, and touch, as they are the main senses engaged when interacting with digital systems.

4. What are key perceptual tasks and their mechanisms?

Key perceptual tasks include:

  • Discrimination: Noticing that a change or difference has occurred in sensory input.
  • Identification: Recognizing and labeling what has changed or what stimulus is present.
  • Estimation: Assessing properties of stimuli, such as size, speed, or quantity.
  • Search: Actively looking for specific stimuli within the environment.

These tasks rely on mechanisms like attention, pattern recognition, and memory to process sensory information effectively.

5. What’s involved in visual perception?

Visual perception involves:

  • Reception of Light: Light enters the eyes and is focused onto the retina.
  • Photoreceptor Activation: Cones and rods in the retina detect color and light intensity.
  • Signal Processing: Neural signals are sent via the optic nerve to the brain.
  • Interpretation: The brain processes these signals to construct images, recognize patterns, and assign meaning.

Visual perception is influenced by factors like attention, context, and prior knowledge, allowing us to interpret complex visual information.

6. How do the basics of the eye work?

The eye functions as follows:

  • Light Entry: Light passes through the cornea and enters the eye via the pupil, whose size is regulated by the iris.

  • Focusing: The lens adjusts shape to focus light onto the retina at the back of the eye.

  • Photoreception

    The retina contains photoreceptors:

    • Cones: Concentrated in the fovea, responsible for color vision and fine detail.
    • Rods: Located in the peripheral areas, sensitive to low light levels, but do not detect color.
  • Signal Transmission: Photoreceptors convert light into electrical signals sent to the brain through the optic nerve.

7. What are Gestalt principles and how are they relevant for HCI?

Gestalt principles are psychological theories explaining how humans naturally organize visual elements into groups or unified wholes when certain principles are applied. Key principles include:

  • Proximity: Elements close to each other are perceived as related.
  • Similarity: Similar items are grouped together.
  • Continuity: The eye follows continuous lines and patterns.
  • Closure: Incomplete figures are perceived as complete.
  • Enclosure: Objects enclosed together are seen as a group.
  • Connection: Connected elements are viewed as part of the same group.

In HCI, applying Gestalt principles helps designers create intuitive and organized interfaces, making it easier for users to process and understand visual information.

8. What are the three central motor tasks?

The three central motor tasks are:

  1. Target Acquisition: Moving a control (e.g., cursor, finger) to a spatially defined target.
    • Discrete Aimed Movements: Reaching for a static target (e.g., clicking a button).
    • Continuous Aimed Movements: Maintaining movement within boundaries (e.g., dragging along a path).
    • Temporally Constrained Movements: Interacting with moving targets within time constraints.
  2. Simple Reaction: Responding quickly to a single stimulus with a predetermined action.
  3. Choice Reaction: Selecting an appropriate response when presented with multiple stimuli and possible actions.

9. What is Fitts’ Law and what can it be used for?

Fitts’ Law predicts the time required to move to and select a target area, based on the distance to the target and the size of the target. The formula is:

\[\text{Movement Time} = a + b \times \log_2\left(\frac{2D}{W}\right)\]

Where:

  • $D$ = Distance to the target
  • $W$ = Width of the target
  • $a$, $b$ = Empirical constants

10. What are the different reaction types?

The different reaction types are:

  • Simple Reaction: A single stimulus requiring a single response (e.g., pressing a button when a light appears).
  • Choice Reaction: Multiple stimuli, each requiring a different response (e.g., pressing different keys based on different signals).

11. What does the Ratcliff model explain?

The Ratcliff Diffusion Model explains how decisions are made over time by accumulating sensory evidence until a threshold is reached. It models reaction times and accuracy in simple and choice reaction tasks by considering factors like decision boundary, drift rate, and non-decision time.

\[\text{Reaction Time} = a + b \times \log_2(N + 1)\]

Where:

  • $N$ = Number of choices
  • $a$, $b$ = Empirical constants

12. What does the Hick-Hyman Law express?

The Hick-Hyman Law states that the time it takes for a person to make a decision increases logarithmically with the number of choices available. The formula is:

\[\text{Reaction Time} = a + b \times \log_2(N + 1)\]

Where:

  • $N$ = Number of choices
  • $a$, $b$ = Empirical constants

13. What are the elementary cognitive abilities?

Elementary cognitive abilities include:

  • Perception: Interpreting sensory information.
  • Attention: Focusing on specific stimuli.
  • Memory: Storing and recalling information.
  • Reasoning: Processing information to make decisions.
  • Decision Making: Choosing between alternatives.
  • Motor Control: Coordinating physical actions.

14. What is cognitive control?

Cognitive control is the ability to direct thought and action in accordance with internal goals. It involves:

  • Goal Setting: Defining objectives.
  • Planning: Outlining steps to achieve goals.
  • Attention Management: Focusing on relevant tasks and filtering out distractions.
  • Inhibition: Suppressing irrelevant or interfering impulses.
  • Task Switching: Shifting focus between tasks when necessary.

15. How to measure cognitive workload?

Cognitive workload can be measured using tools like the NASA Task Load Index (NASA-TLX), which assesses workload based on six dimensions:

  1. Mental Demand
  2. Physical Demand
  3. Temporal Demand
  4. Performance
  5. Effort
  6. Frustration Level

Users rate each dimension after task completion, providing insight into the cognitive demands of a task or interface.

16. What types of memory do we have and how do they differ?

We have two main types of memory:

  1. Short-Term Memory (Working Memory):

    • Capacity: Limited (about 7±2 items).
    • Duration: Brief (seconds to minutes).
    • Function: Holds information temporarily for processing.

  2. Long-Term Memory:

    • Capacity: Potentially unlimited.

    • Duration: Long-lasting (days to years).

    • Subtypes:

      • Declarative Memory (Explicit)

        :

        • Semantic Memory: Facts and general knowledge.
        • Episodic Memory: Personal experiences and events.

      • Non-Declarative Memory (Implicit)

        :

        • Procedural Memory: Skills and habits (e.g., riding a bike).
        • Conditioning: Learned associations and responses.

17. What governs learning over time?

Learning over time is governed by:

  • Repetition: Repeated exposure strengthens memory traces.
  • Reinforcement: Positive outcomes encourage repetition of behaviors.
  • Consolidation: The process by which short-term memories become long-term.
  • Forgetting: Lack of use leads to memory decay.
  • Feedback: Information about performance that guides future actions.

18. What are the two systems of decision making?

The two systems of decision making are:

  1. System 1 (Intuitive):
    • Fast, automatic, and unconscious.
    • Relies on heuristics and past experiences.
    • Used for quick judgments and routine decisions.
  2. System 2 (Analytical):
    • Slow, deliberate, and conscious.
    • Involves reasoning and critical thinking.
    • Used for complex decisions requiring attention.

19. What’s a mental model?

A mental model is an internal representation of how a system or process works. It helps individuals understand, predict, and interact with the system by providing a framework of expectations. In HCI, users’ mental models guide how they use interfaces, influencing their actions and interpretations.

20. How can insights about cognition be applied to HCI?

Insights about cognition can be applied to HCI by:

  • Reducing Cognitive Load: Simplifying interfaces to align with memory limitations.
  • Designing for Attention: Highlighting important elements and minimizing distractions.
  • Supporting Mental Models: Creating interfaces that match users’ expectations.
  • Enhancing Learnability: Using consistent design patterns to facilitate learning.
  • Improving Decision Making: Limiting choices to reduce decision fatigue.

21. What does it mean to view the human as an information processor?

Viewing the human as an information processor means treating human cognition similar to a computer system that:

  • Receives Input: Sensory information from the environment.
  • Processes Information: Interprets and manipulates data using cognitive functions.
  • Produces Output: Responses or actions based on processing.

This perspective helps in modeling human interaction with systems, allowing for predictions about performance and behavior.

22. What is the Model Human Processor (MHP), what does it consist of, and what can it be used for?

The Model Human Processor is a theoretical model that describes human cognitive processing in terms of three interacting subsystems:

  1. Perceptual Processor:
    • Handles sensory input (visual, auditory).
    • Cycle time: ~100 milliseconds.
  2. Cognitive Processor:
    • Manages memory and decision-making.
    • Cycle time: ~70 milliseconds.
  3. Motor Processor:
    • Controls physical actions and responses.
    • Cycle time: ~70 milliseconds.

The MHP is used to predict human performance in HCI tasks, such as estimating how long a user will take to respond to a stimulus or complete an action.

23. What is the performance of our perceptual, cognitive, and motor systems according to the MHP?

According to the MHP:

  • Perceptual Processor:
    • Cycle Time: Approximately 100 milliseconds.
    • Function: Processes sensory inputs.
  • Cognitive Processor:
    • Cycle Time: Approximately 70 milliseconds.
    • Function: Handles memory retrieval, decision-making.
  • Motor Processor:
    • Cycle Time: Approximately 70 milliseconds.
    • Function: Initiates and controls physical movements.

These cycle times help estimate the total time required for a user to perceive, process, and respond to stimuli.

24. What are the limitations of the MHP?

Limitations of the MHP include:

  • Simplification: It oversimplifies complex human behaviors and cognitive processes.
  • Variability: Doesn’t account for individual differences in processing speeds.
  • Context Ignorance: Lacks consideration of environmental and emotional factors.
  • Dynamic Changes: Doesn’t account for learning effects or changes over time.

25. How are needs and motivations relevant to HCI?

Needs and motivations influence how users interact with systems. By understanding these factors, designers can:

  • Enhance User Engagement: Aligning interfaces with users’ intrinsic motivations.
  • Improve Satisfaction: Meeting users’ psychological needs leads to positive experiences.
  • Increase Usability: Designing features that fulfill users’ goals efficiently.

26. What is Self-Determination Theory, its assumptions, and basic ideas?

Self-Determination Theory (SDT) is a framework for understanding human motivation, positing that people are driven by innate psychological needs:

  • Autonomy: Desire for self-direction and control over actions.
  • Competence: Need to feel effective and master skills.
  • Relatedness: Aspiration to connect with others and belong.

SDT assumes that satisfying these needs enhances intrinsic motivation, leading to greater engagement and well-being. In HCI, applying SDT means designing systems that support these needs, fostering more meaningful and motivating user experiences.

Human Computer Interaction, Overview
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