User Modeling

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User Modeling

• Models of the User in Design

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Outline

• Review
• Socio-Technical Models
• Soft Systems Methodology
• Physical and Device Models
• Cognitive Architectures
• Last two lead into human abilities (next day)
• Summary
• Administratia

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Contextual Inquiry

• Three basic techniques
• Interviewer-Interviewee
• Scientist-Subject
• Master-Apprentice
• Each has strengths and weaknesses
• Cost
• Time
• Completeness

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User Modeling and Task Analysis

• GOMS
• Goals, Operators, Methods, Selection
• Works well inside software
• A post-hoc methodology
• HTA
• Works well to analyze specific tasks in terms of
  subtask and ordering
• Workflow understanding
• All a struggle to specify requirements

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User modeling continued

• Look at more encompassing techniques today
• Socio-technical and SSM
• Based on expanding systems beyond hardware
• Physical and device models
• For prediction of time taken for operations
• Leads into human abilities
• Cognitive architectures
• Consider the potential for user error

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Socio-Technical Models

• USTM/CUSTOM
• OSTA
• Ethics
• Try to encompass the technical, social,
  organizational and human aspects of design

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USTM/CUSTOM

• Uses diagrammatic task models and English
  descriptions
• Goal is to combine structured methods like HTA
  with human factors
• USTM is larger version
• CUSTOM is a variant used by small organizations
• CUSTOM also has a very short version represented
  by a set of questions

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CUSTOM

• Goal of CUSTOM is to establish stakeholder
  requirements
• Anyone who is impacted by the systems success or
  failure
• Separated into four levels
• Primary Direct users
• Secondary Those who dont use system but
  receive output or provide input
• Tertiary Those who are also affected but wont
  necessarily ever have direct contact with system
• Facilitating Designers and developers of the
  system

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CUSTOM

• Applied early in design
• Product opportunity stage
• Manual including forms and questions
• Set of questions such as
• Describe the organizational context
• Identify stakeholders
• Identify work-groups
• Identify task-object pairs
• Identify stakeholder needs
• Consolidate and check requirements

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CUSTOM

• Fairly straightforward
• Gives good overview of system tasks from all
  perspectives
• Time consuming and cumbersome for many systems
• Secondary and Tertiary stakeholder lists can get
  huge
• Also bogged down in facilitator tasks

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Shortened custom

• Given a stakeholder
• What does stakeholder have to achieve?
• Sources of satisfaction and dissatisfaction
• Knowledge and skills
• Attitude towards work and technology
• Work group attributes that might affect success
  of technology with stakeholder
• What task in terms of frequency, fragmentation,
  and choice of actions
• Responsibility, security and privacy issues?
• Physical conditions where work is performed.
• Basically just understand the person you are
  designing for!

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OSTA

• Open Systems Task Analysis
• Specifies social aspects of system with technical
  aspects
• Goal is to understand how a computer will
  transform the workplace
• Results are depicted in flow charts and
  descriptions (prose)

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OSTA steps

• Specify primary task
• Identify task inputs
• Analyze external environment
• Physical, economic, political, demand for output
• Importance varies e.g. public or private system
• Transformation processes are described
• Inputs to outputs
• Social system is analyzed
• Roles of people
• Technical system is analyzed
• How new system integrates with old work practices
• Performance satisfaction
• Social system requirements
• Technical requirements stated
• Functionality, usability criteria, etc.

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ETHICS

• Addresses social and technical issues using
  separate design teams
• Design teams work separately and then attempt to
  merge solutions
• Tries to generate multiple solutions and select
  solution which does well in both technical and
  social aspects

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ETHICS

• Problem is identified. Objectives and tasks
  identified. Job satisfaction requirements
  specified
• Two design teams are established
• Alternative solutions against criteria
  established in (1)
• Solutions checked for compatibility
• Compatible solutions ranked against criteria
• Detailed designs developed
• The bridge-building problem
• Meeting in the middle

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Summary of Socio-Technical

• Many different models but one focus
• Understand both the social and technical aspects
  of the system
• Human and technology perspective on all solutions
• In some ways, technical gets in the way
• Emphasizes designing a solution rather than
  understanding the situation

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Soft Systems Methodology

• Focuses on understanding situation
• Views technology and people as components
• Flexible approach to detailed consideration of
  context
• Soft
• No single answer
• Takes practice to use effectively
• Only useful if it helps developer understand the
  wider system

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SSM

• First recognize problem and develop a rich
  picture
• Stakeholders, tasks, groups, organizational
  structure, etc.
• Lots of contextual inquiry
• Move to system world and generate a root
  definition
• Can be from any (or each) stakeholders
  perspective
• Build conceptual model
• What system must do
• Hierarchical modeling of transformations and
  activities
• Check the system for compatibility and make
  improvements

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Physical and Device Models

• Two models
• Keystroke level model
• Three-state model
• Based on analyzing the human motor system to
  accomplish a task

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Keystroke-level model

• Predicts user performance
• Widely known and conceived of by Card et al.
• Short tasks, particularly commands (from the
  command line interface days)
• Allows calculation of performance by experienced
  users
• Based on model human processor
• Soon

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KLM

• Tasks can be described as operators
• K keystroking 0.35s
• P pointing 1.10s
• H homing 0.4s
• D drawing variable with length of line
• M Mental operator 1.35s
• R response operator by system 1.2s
• Sum up times for each operator in a given task
  and you know how long itll take

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Three-state model

• Three states describe an input device

Put mouse down
Press mouse button
State 0 No feedback
State 1 Tracking
State 2 Dragging
Release mouse button
Pick mouse up
NOTE that mouse button is held down while
dragging why?
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Commentary

• Note that were back at the software
• Post hoc techniques
• Program must exist
• Maybe you start with software, so not a bad
  assumption
• In usability work, youre usually fixing broken
  things

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Cognitive architectures

• All formalisms have some notion of cognitive
  processing
• Consider the mental operator in KLM
• Can also view user as an information processing
  machine
• An Information Processor that makes errors, as
  well
• Note that we havent modeled user error yet

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Problem space model

• Like an agent moving through environment
• Knowledge-level system a system exhibiting
  rational behavior
• Creates a Problem Space Model of system
• Four activities occur
• Goal formulation
• Operation selection
• Operation application
• Goal completion
• Has been used to create programmable user models
• Allows understanding of the stacking of problem
  spaces to accomplish a goal
• Measures cognitive load on the user

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Interacting cognitive subsystems

• Provides a model of perception, cognition, and
  action
• Views user as information processing system, not
  as a performer of actions
• Built by examining the interaction of nine
  subsystems
• Five peripheral sensors
• Four central systems for mental processes
• Visual system to see world for peripheral
• Capturing propositional information (i.e.
  entities, attributes and relationships) for
  mental
• Can be used to explain how a user proceduralizes
  action

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Summary

• Many different ways to model user
• The problem space
• socio-technical models and SSM
• Within the application
• GOMS
• Actions performed
• HTA
• Mental processes and cognitive load
• Problem space and cognitive subsystems
• Next step is to refine our ability to model these
  things by looking at human abilities

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Administratia

• Web applet design project
• Project Group Assignments and Projects

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Group Assignments and Projects
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