Chapter 11 Phase 5 : Worker Competencies Analysis

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Chapter 11Phase 5 Worker Competencies Analysis

• ? ? ?

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Purpose

• The fifth phase of CWA
• To address the traditional core concerns of the
  HF and HCI community
• To identify the competencies that an ideal worker
  should exhibit
• Two steps to consider
• To consolidate the requirements imposed by the
  previous phases
• To determine how those requirements can be met in
  a way that is consistent with human limitations
  and capabilities
• Modeling tool SRK taxonomy
• A framework within which domain requirements and
  existing knowledge of human cognition can be
  integrated
• An example using the DURESS II process control
  microworld

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The ecological approach revisited
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• Funneling in with each successive phase
• Reducing the degree of freedom
• From environment constraints to cognitive
  constrains

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From cognitive constraints to system design

• There are much knowledge of human capabilities
  and limitations
• Highly fragmented and applicable only to narrow
  psychological phenomena
• Potentially relevant to systems design
• A challenge in worker competencies analysis
• To pull together requirements of the application
  domain and the relevant subset of existing
  knowledge about human cognition in a integrated
  way
• To derive practical implications for system design

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The origin of Skills, Rules, Knowledge taxonomy

• Rasmussen (1983) ??
• To help organize relevant knowledge into a form
  that is more useful for system design
• As Sanderson and Harwood(1988) It is easy to
  misinterpret SRK taxonomy

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A taxonomy, not a model

• The taxonomy provides a set of distinctions, not
  a detailed model of psychological processes
• One of the primary criteria in the development of
  the taxonomy is usefulness, not necessarily
  truth.
• Each level in the taxonomy corresponds to a
  category of human performance
• Respecting these distinctions should make it
  easier to develop models for each category of
  human performance

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Criteria to distinguish categories of human
performance

• Dependent on its purpose
• SRK taxonomy is defined by
• Distinguishing categories of human behavior
  according to fundamentally different ways of
  representing the constraints in the environments
• Unpack these premises into a series of logical
  steps
• Goal-directed interaction between a worker and an
  environment depends on constraints
• Constraints that need to be taken into account
  can be represented by workers in fundamentally
  different ways
• Each of these ways taking into account
  action-relevant constraints is linked or defines,
  a different categories of human performance

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Logical steps to unpack the premises

• Goal-directed interaction between a worker and an
  environment depends on constraints
• Ex) gravity ? ??
• Different types of constraints that are relevant
  to the workers current goals work domain
  constraints, control task constraints
• Constraints that need to be taken into account
  can be represented by workers in fundamentally
  different ways
• One by reasoning analytically using a symbolic
  representation of Newtons law
• Two by a set of instructions that would specify
  what actions should be taken
• Three by an internal embodiment (or implicit
  model) of the relevant dynamics to continuously
  guide actions
• Each of these ways taking into account
  action-relevant constraints is linked or defines,
  a different categories of human performance (??)

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Action-relevant constraints human performance

• KBB is defined by serial, analytical reasoning
  based on a symbolic representation of the
  relevant constraints in the environment.
• KBB guides action by representing the
  goal-relevant constraints in the environment as
  a mental model
• RBB is defined by an if-then mapping between a
  familiar perceptual cue in the environment and an
  appropriate action
• No reasoning is required and there is a direct
  association between a cue and an action
• RBB guides action by representing the
  goal-relevant constraints in the environment in
  terms of perceptually grounded rules
• SBB is defined by real-time, direct coupling to
  the environment via dynamic world model
• Dynamic world model is only an implicit model of
  the environment
• If skilled in motor control, actions are
  successful without having to represent gravity
  explicitly internally.
• Just as the representation of information in an
  analog computer corresponds to its physical
  structure
• By providing a basis for direct coupling and
  parallel, continuous interaction with the world

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Relation between levels of cognitive control in
SRK taxonomy and the way in which constraints in
the environment are represented and processed
internally
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Internal representation Skill-based behavior

• Smooth, automated, and highly integrated patterns
  of action that are performed without conscious
  attention
• Typical example automated psychomotor activity
  (e.g. walking) that is driven by a continuous
  perception-action loop
• Anticipatory actions, direct coupling to the
  environment, prototypical temporal-spatial
  patterns, non-verbalized.

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Internal representation Rule-based behavior

• Stored rules derived from procedures, experience,
  instruction, or previous problem-solving
  activities
• Action is goal-oriented but goals are not
  explicitly represented. Goals can only implicitly
  be found in the structure of the rules.
• The rule will reflect the functional properties
  of the environment that constrain action
• People are not reasoning they are merely using
  familiar perceptual cues in the environment to
  trigger actions directly
• Workers are usually aware of their cognitive
  activities at the RBB and thus verbalize their
  thought

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Internal representation Knowledge-based behavior

• Deliberate serial search based on an explicit
  representation of the goal and a mental of the
  functional properties of the environment
• Goals are considered explicitly rather than
  implicitly
• Slow serial and effortful because it requires
  conscious, focal attention
• Frequently used unfamiliar situations where
  previous experience is no longer valid and a
  solution must be improvised by reasoning

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The SRK taxonomy of human performance
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The role of information interpretation signal,
sign, symbols

• The three levels are distinguished
• according to the way in which workers interpret
  information from the environment (Signals, Signs
  and Symbols)
• by the kinds of internal representation
• Signals
• Signals have a strong perceptual basis because
  they are continuous quantitative indicators of
  the time-space behavior of the environment
• The changing distance between your car and the
  lane markers may be a time-space signal
• Signs
• Signs are arbitrary but familiar perceptual cues
  in the environment. They refers to the state of
  the world by convention or by prior experience
• A red octagon with the word stop may be a sign
• Symbols
• Symbols are meaningful formal structures that
  represent the functional properties of the
  environment
• Your knowledge of the cars components are
  represented as symbols in a mental model (??? ???
  ?? ???? ??? ??? ?? ??? ???? ??)

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Signal, Sign, Symbol distinctions

• The concepts refer to the way in which an
  observer interprets information,
• not just to the form in which information is
  presented
• The very same display may be interpreted as a
  signals as a sign or as a symbol
• Signals and signs have a perceptual basis,
  whereas symbols have a semantic basis
• Both signals and signs refer to perceptual
  properties of the environment such as distance,
  color and size
• Symbols although they may take a particular form,
  refer to the meaning of the information, not its
  form

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A hypothetical example showing the difference
between signals, signs and symbols
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Interactions between levels (I)

• The interactions between levels are best
  appreciated by adopting a temporal perspective.
• Synchronous activities
• Those that occur online and in-real and deal with
  the current situation
• Workers is directly coupled to spatial-temporal
  properties in the environment
• Continuous steering your car to make sure that it
  is within the lane markers
• Synchronic activities
• Those that occur online and real time, but they
  deal with the sings that are used to trigger new
  SBB activities
• Such activities fall into the realm of RBB
• You hear your engine revving up to a familiar
  reference pitch, so you shift gears.
• For an experienced driver, the act of changing
  gears would take lace at the SBB level (direct
  coupling to the time-space properties of the
  environment

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Interactions between levels (II)

• Diachronic activities
• Occur offline and require evaluation or planning.
  They involve using previous experience to
  interpret the world in terms of signs that could
  trigger SBB activities
• Those deal with what has occurred in the past and
  may occur again in the future
• Recognizing a familiar stretch of highway that in
  the past, has been followed by an icy patch of
  road.
• Achronic activities
• Occur offline and require evaluation or planning
• They involve reasoning in symbolic terms , not
  associating actions based on familiar perceptual
  signs.

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Interactions between the different levels of
cognitive control
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Avoiding some misconceptions (I)

• A continuum with completely preattentive,
  automatic processing on the skill-based end and
  completely attentive, controlled processing on
  the knowledge-based end
• The three ways of interpreting information are
  discrete concepts that do not lie on a continuum.
• Nothing in between the two (signal and sign)
• Actions directly on the world are only possible
  at the SBB
• Actions on the world are driven by automated
  sensorimotor patterns at the SBB level (?? ??)

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Avoiding some misconceptions (II)

• To classify tasks as belonging solely to one of
  the three levels in the taxonomy
• Such an interpretation would be overly simplistic
• There are interactions among three levels (???
  ??)
• SBB level is always active and is responsible for
  directing attention, activating higher levels,
  controlling information gathering as well as
  transferring intentions into control of movements
• The relationship between a particular task and
  levels of cognitive control is not fixed because
  it can be mediated by several variables
• Workers level of expertise novice may have to
  resort to KBB, but expert may enable RBB
• The form in which information is presented
  graphic form (lower level), alphanumeric form
  (higher level)
• The degree to which workers reflect on their
  performance Unreflective worker (using RBB and
  SBB), Reflective worker (using KBB)

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Examples of its usage

• A taxonomy of human performance models
• Stages of skill acquisition
• Theories of expertise effects in the memory
  recall
• A framework for interface design for complex
  sociotechnical systems

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Mapping of human performance models onto the SRK
taxonomy
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Stages of skill acquisition (1)

• Five stages of skill acquisition (Dreyfus
  Dreyfus 1988)
• Novice students learn explicit facts, features
  and rules that can be readily verbalized.
  Context-free
• Advanced beginner students begins to take into
  account more contextual factors and thus develop
  more sophisticated rules for performing a task
• Competent performer students use specific goals
  to prioritize facts according to their relevance
• Proficient performer activity at this stage is
  the result of experience-based associations
  connecting context and current stimuli with plans
  that have proven to be successful
• Expert students are able to deal with task
  demands in an effortless and automatic fashion.

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Stages of skill acquisition (2)

• Reinterpretation by SRK taxonomy (Olsen and
  Rasmussen, 1989)
• Expertise is not a fixed property of a person,
  but rather a dynamically varying relationship
  between the demands imposed by the environment
  and the resources of a particular person
• Additional implications
• Learning can take place within each level ex)
  learning to talk or walk involves exploration and
  development within the SBB level
• Differentiating expertise at different levels
  also highlights the issue of meta-expertise
  meta-expertise? ???? ?? ??? ??? ?.

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Theories of expertise effects in the memory
recall (1)

• Relationship between expertise and memory recall
  performance
• Chess master were able to reconstruct perfectly a
  chess position
• Perceptual chunking theory
• These chunks are perceptually structures that
  contains information about patterns of pieces on
  a chessboard
• Experts can recognize and code familiar chunks of
  pieces
• Conceptual chunking theory
• This is based on the meaningfulness of the
  material to be recalled, not its perceptual form
• Experts skill is a result of the organization of
  functional concepts in long-term memory

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Theories of expertise effects in the memory
recall (2)

• To develop an integrative theoretical account of
  the chunking phenomenon by the SRK taxonomy
• The perceptual account draws on the RBB level
• The environment (i.e. the set of pieces to be
  recalled) is interpreted as signs (i.e. familiar
  perceptual cues) that correspond to groups of
  chess pieces.
• Chunking is possible because of a recognition
  process
• The conceptual account draws on the KBB level
• The environment is interpreted as symbols (i.e.
  knowledge structures) that correspond to
  meaningful relationship between chess pieces.
• Chunking is possible because of conceptual
  inference
• These processes can interact and chunking can be
  driven by a combination of the two levels.

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A framework for interface design for complex
sociotechnical systems

• ???? ???? ???? ??????? research issue?? ??? ????
  ??? ?? SRK taxonomy??. ??? To develop design
  principles (Ecological Interface Design)
• 3 steps of EID framework ??
• Literature review on interface design
• SRK taxonomy as an framework to integrate the
  variety of research results
• To deduce a set of three principles for interface
  design

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Theoretical rationale behind the development of
the EID framework
Greater the skill, lower the level
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A framework for interface design

• Interface should achieve twofold goals
• To design interfaces in such a way as not to
  force cognitive control to a higher level than
  the demands of the task require
• To provide the appropriate support for all three
  levels
• 3 design principles
• SBB- To support interaction via time-space
  signals, workers should be able to act directly
  on the display
• RBB- Provide a consistent one-to-one mapping
  between the work domain constraints and the cues
  or signs provided by the interface.
• KBB- Represent the work domain in the form of an
  abstraction hierarchy to serve as an
  externalized, faithful model that will support
  knowledge-based problem solving

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For process control microworld (1)

• Skill-Based Behavior
• Workers should have basic perceptual skills
• Workers should be able to interact directly with
  the display rather than using command language
• Timing is a very important aspect of proficient
  control in DRUESS II (visualization e.g. time
  constants, rates of change)
• Rule-Based Behavior
• Worker competencies at the RBB level can be
  divided into tow categories
• To create salient perceptual cues
• To be aware of the various shortcut and
  strategies that they can use to effectively
  control the process

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For process control microworld (2)

• Creating signs
• Graphical visualization of the mass balance
  constraints
• Ensuring that workers are aware of procedural
  constraints that can be exploited to control the
  process
• Pumps should not be turned on before valves (In
  the control task and strategies analysis)
• Knowledge-Based Behavior
• By presenting these relationship (Identified in
  WDA) in the interface, we would be creating a
  faithful, external model of the process that
  workers could use during problem solving
• Serve as the basis for a training program

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Summary
Cognitive Work Analysis Framework
Cognitive Work Analysis
Systems Design
Identify
Form
Realize
Build
Develop
Conceptual Distinctions
Modeling Tools
Models of Intrinsic Work Constraints
Systems Design Interventions
v
1. Work Domain
1.
1.
1. Sensors, models, database
Abstraction- Decomposition
v
2. Control Tasks
2.
2.
2. Procedures, automation, context-sensitive
interface
Decision ladder
v
Information Flow Map
3. Strategies
3.
3.
3. Dialogue modes, process flow
All of the above
v
4. Social-Organizational
4.
4.
4. Role allocation, organizational, structure
5. Worker Competencies
5.
5.
5. Selection, training, interface form