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CMT 3210: Understanding the human element in HCI

CMT 3210: Understanding the human element in HCI. Lecture 4 Models of human-Computer Interaction Mental Models Elke Duncker. Models of Human-Computer Interaction. Normans 7 stage model Human Processor model. Evaluation and execution. Goal. Approximate model of how people carry out tasks

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CMT 3210: Understanding the human element in HCI

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  1. CMT 3210: Understanding the human element in HCI Lecture 4 Models of human-Computer Interaction Mental Models Elke Duncker

  2. Models of Human-Computer Interaction • Normans 7 stage model • Human Processor model

  3. Evaluation and execution Goal • Approximate model of how people carry out tasks • Emphasises carrying out actions and getting feedback Execution: Carrying out actions on the world Evaluation: Comparing what happened with what we wanted The World

  4. Cyclic model of human action Goal • Seven stage process • Can start anywhere Intention formation Evaluation Action specification Interpretation Execution Perception The World

  5. Gulfs of execution and evaluation • Gulf of execution: • How does the user translate intentions into action? • Gulf of evaluation: • How does the user understand the effects of actions and does s/he tell when her/his goals are satisfied? Execution Goals World Evaluation

  6. Bridging the gulfs • Execution • Mappings: are actions designed so the user make the connection between the effects they intend to achieve and the actions provided by the system? • Evaluation • Feedback: is information about the system state provided in a way that allows users to determine whether goals are satisfied?

  7. Using the model as a design aid • How easy is it for the user to: Determine the function of the device Tell what actions are possible Tell if system in desired state Determine mapping from intention to action Determine mapping from state to interpretation Perform the action Tell what state the system is in

  8. Principles for good design • Visibility • of the state of device and possibilities for action? • Good conceptual model • consistent presentation, coherent system image? • Good mappings • relation between actions and effects? • Feedback • about effects of actions?

  9. A model of human information processing Model Human Processor • Detailed model of how computer users process information • Intended to help designers do predictions • Consists of specialised concurrent processing units and memories • characterised by speed, decay time, capacity, encoding

  10. Auditory memory Visual memory Model Human Processor Stimulus Perception Motor processor Cognitive processor Working memory Long-term memory

  11. Principles of the MHP • Perception takes time - depends on stimulus intensity • Processing takes time - depends on task demands, information load, practice • Different encoding used at different stages • Users act rationally (most of the time): Goals + Task + Operators + Inputs + Knowledge + Processor limits Behaviour

  12. Applications in HCI • The GOMS and KLM analysis techniques • Identifies kinds of processing and memory • Identifies possible concurrency

  13. Comparing the models • MHP almost exclusively about what goes on inside the head • Focus on human performance - especially time • Norman's model more about human-machine interaction • without saying how processes are implemented or what exists in the head • Distinguish between "in the head" and "in the world"

  14. Knowledge in the head and in the world • Knowledge needed to translate intentions into plans and actions may be • remembered by the user (in the head) • e.g. unix commands • embedded in the devices used (in the world) • e.g. direct manipulation interfaces

  15. Summary HCI models • Norman's 7 stage model of human action • Identifies processes involved in action • Doesn't specify how they take place • Useful as a tool for thinking and analysis • Consideration of "in the head" / "in the world" • Model Human Processor • Detailed account of human information processing • Specifies how internal processes work • Used for making predictions (e.g. GOMS) • Framework for topics that will come later

  16. Mental Models • A person’s image about an artefact • The user’s image about the machine • Making sense of the world from inside

  17. Mental Models • An internal representation of a system that can be interrogated and manipulated. • ·Mental models are concrete. • ·Mental models can be run. • ·Mental models are constructed from experience. • Mental models are generally incomplete and inaccurate, but serve a purpose

  18. Example Camera • What are the components and how do they fit together? • How does it work? • What causes what? • How do you use it? • How do you use your understanding when something goes wrong?

  19. Example: London Underground Map • • what is it good for? • • what isn’t it much use for?

  20. The Contents of a Model • Kieras (1982) categorised the kinds of knowledge that people have about a device as follows. • Label or name of the device • Function or purpose (what goals can be accomplished) • Controls and indicators • Inputs, outputs and connections • Power sources and requirements

  21. Contents of a Model (cont.) • External layout and appearance • Internal layout and appearance • External behaviour (input-output function) • How to operate the device to accomplish goals • Procedures for troubleshooting and maintenance • Internal structure and mechanisms (how it works)

  22. Mental Models • A runnable mental model = how-it-works knowledge + knowledge how-to-use-the-how-it-works-knowledge ! • How-it-works knowledge may be at various levels of detail. • Strategic knowledge includes various strategies — e.g. inference, prediction, diagnosis. These are transferable skills.

  23. Origin of mental models • a) declarative and procedural models • b) feedback, hypothesis-testing (but beware mode errors) • c) manuals and help systems • d) analogy and metaphors • e) designer’s conceptual model:

  24. Designer’s conceptual model User’s mental model Interface design How designers influence the user’s mental model

  25. Note • This view puts the designer at the centre • It is the designer’s job is to enable the user to assimilate their view by getting the device to project an appropriate image of itself. • This is necessary for device-only constructs (where the challenge is to make these as easy to learn and make sense of as possible).

  26. Domains and devices • 'Mental models' are about understanding the device [and its representation of the domain]. • User may be: • manipulating domain through device, or • investigating domain through device

  27. Further Reading • For the execution-evaluation model: • Donald Norman "The Design of Everyday Things” (also appeared as "The Psychology of Everyday Things") • For the Model Human Processor: • Stuart Card, Thomas Moran and Alan Newell "The Psychology of Human Computer Interaction"

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