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Human Performance 1H2

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Title: Human Performance 1H2


1
Human Performance 1H2
Chris Baber
2
Lectures Labs
  • Lectures
  • Thursday 1-3 room 123
  • Labs
  • Weeks 4-10
  • Friday mornings data collection exercises
  • Each data collection exercise running over three
    week period
  • Each session will involve group work

3
Assessment
  • Course-work (50)
  • ONE lab report (45)
  • 2500 words
  • to be handed in THURSDAY week 11
  • to describe data collection and apply principles
    from lectures
  • Attendance of sessions (5)
  • Examination (50)
  • 2 questions from 3
  • 1½ hours

4
Report Marking Scheme
  • Summary 10
  • Introduction
  • Rationale 5
  • Review 15
  • Hypothesis 5
  • Method 25
  • Results 15
  • Conclusions 20
  • References 5

5
Module Objectives
  • Relate cognitive psychology to human-centred
    system design
  • Employ basic concepts from cognitive psychology
  • Describe the use of products in terms of the
    requisite cognitive activities.

6
Reading List
  • Norman, D.A.
  • The Design of Everyday Things
  • New York Basic Books, 1990
  • http//www.baddesigns.com/index.shtml
  • Noyes, J.M. and Baber, C.
  • User-Centred Design of Systems
  • Berlin Springer-Verlag, 1999
  • Smyth, M.M. et al.
  • Cognition in Action
  • London LEA, 1987

Matthews, G., Davies, D.R., Westerman, S.J. and
Stammers, R.B., Human Performance London
Psychology Press, 2000 Wickens,
C.D. Engineering Psychology and Human
Performance, New York Harper Collins, 1992
7
Session One Working Assumptions about using
Devices (from 1H1)
8
User centred design
  • User as focus of design
  • Actual user can be observed or questioned
  • Models of use can be created

9
Requirements for model
  • Capture everyday behaviour
  • Predict consequences of design
  • Guide design concept and evaluation
  • Explain problems and errors

10
Assumptions
  • Much of everyday behaviour is automatic
  • Requires little conscious control
  • Involves learned routines
  • Involves expectation (based on previous
    experience)
  • Is error-free (or at least, error-recoverable)
  • Is skilled (i.e., well-practised)

11
Seven Stage Action ModelNorman, 1990
GOAL OF PERSON
12
Exercise 1
  • Use the Seven Stage model to represent the
    activities associated with withdrawing 20 from a
    cashpoint machine

13
Session TwoSolving Problems
14
Problem Solving
  • A problem is something that doesnt solve easily
  • A problem doesnt solve easily because
  • you dont have the necessary knowledge or,
  • you have misrepresented part of the problem
  • If at first you dont succeed, try something else
  • Tackle one part of the problem and other parts
    may fall into place

15
Exercise 2
Join all of the dots Using a single line DO
NOT lift your pen off the paper
16
Conclusion
  • More than one solution
  • Solution limited by boundary conditions
  • Active involvement and testing

17
Exercise 3
  • Representation affects strategy
  • Convert from Roman to Arabic
  • Strategy developed for one version might be
    inefficient in another version
  • Convert numerals or just see 4
  • XXXVII XIV
  • XXXX X

18
Conclusion
  • Means-ends analysis
  • To modify representation
  • Break problem into subproblems
  • To test hypothesis through trial and error

19
SUDOKU analysis
  • From the verbal protocols
  • How many times did the person refer to the
    rules?
  • How many times did the current version of the
    problem constrain their choice?
  • How many times did they act in terms of trial
    and error?

20
Describing Problem Solving
  • Initial State
  • Goal State
  • All possible intervening states
  • Problem Space
  • Path Constraints
  • State Action Tree

21
Key issues
  • Insight in some problems
  • Framing
  • Recognition of affordances
  • Reframing of problem
  • Through representation
  • Through changing states
  • Through analogy

22
Using Analogy
  • Target problem
  • Analogue source
  • Surface similarities
  • Same sort of objects
  • Structural similarities
  • Common features or organisation

23
Using Analogy
  • You are a doctor faced with a patient who has a
    malignant growth in his stomach. It is impossible
    to operate on the patient, but the growth needs
    to be treated. There is a ray you can use. If the
    ray is strong enough it can destroy the growth.
    However if the ray is too strong is can also
    destroy tissue. If the ray is too weak it will
    not affect the growth.
  • A fortress is located in the centre of the
    country. Many roads radiate from the fortress.
    You want to capture the fortress. The roads
    might be mined, so you cant attack on one road
    without risk of losing all of your troops.
    However an attack by one group is not enough and
    you need to attack with all of your troops.

24
Analogue Solution
  • Rather than a single source, use multiple sources
  • Triangulate low dose sources onto single spot

25
Expert Problem Solving
  • Expert performance in problem solving can differ
    from novices
  • More knowledge about particular field
  • Knowledge organised differently
  • Problems features recognised differently, e.g.,
    inclined planes vs. conservation of energy
  • More time on analysing problem
  • Performance outside field similar to novices

26
Session Three Knowledge in the head versus
knowledge in the world
27
Knowledge in the HeadKnowledge in the World
  • Menus relieve users of the need to remember
    command names, but not of the need to know what
    functions can be performed by some commands
  • Mayes et al., 1988
  • Knowledge held by users and recalled
  • Knowledge prompted by objects in world

28
Knowledge in the Worldexternal representations
and cognitive artefacts
29
Mapping
  • Naturalness
  • Related to directness of mapping
  • Related to expertise / familiarity
  • Appropriateness
  • Information should be appropriate to the task
    (neither more nor less)

30
Compatibility (see 1H1 notes)
  • Direction of motion stereotypes
  • Affordance
  • S-R compatibility
  • S-C-R compatibility

31
Artefacts Representation
  • Surface representation
  • Display and maintenance of symbols on a visible
    surface
  • Internal representation
  • Storage and organisation of symbols
  • External representation

32
Things that make us smart
  • Cognitive Artefacts used to assist everyday
    activity
  • Shopping List
  • Knotted handkerchief
  • Calculator
  • Diary

33
Using an Abacus for Addition
Heaven beads 5 each
  • 6 2 8

Earth beads 1 each
8 2 10
34
Shopping Lists
  • Construct list
  • Using the process of writing the list to support
    decision making
  • Remember to consult list
  • Check the list during shopping
  • Use the list to help navigate the store
  • Reading and interpret list
  • Make sure everything is bought

35
Shopping Lists
  • Memory aid
  • Do we only buy whats on the list?
  • Do we buy items not on the list?
  • Additional tasks
  • Does writing the list create a new task?
  • Modified task
  • Does using the list change the way we shop?

36
Cognitive Artefacts
  • Distribute actions across time
  • Pre-computation
  • Distribute actions across actors
  • Distributed cognition
  • Change actions required

37
Calculating Ships Speed
  • DRT, (RD/T) using pencil and paper
  • DRT, using calculator
  • 3-minute rule
  • 3-minutes 1/20 of an hour, and 100yds in 1/20
    of a nautical mile
  • ? 1500 yds in 3 minutes 15nmph

38
Calculating Ships Speed
  • DRT, (RD/T) using pencil and paper
  • DRT, using calculator
  • 3-minute rule
  • 3-minutes 1/20 of an hour, and 100yds in 1/20
    of a nautical mile
  • ? 1500 yds in 3 minutes 15nmph
  • 4. Nautical Slide Rule

39
Calculating Ships Speed
  • Knowledge-in-the-World
  • Nautical slide rule
  • Replace calculation with manipulation
  • Colleagues
  • Draw upon experience of others
  • Teamwork
  • Plotter
  • Bearing taker
  • Bearing timer-recorder

40
Calculating Noise Exposure
Nomogram versus Calculation
  • LEP,d log ftot. 90

dB(A)
0.1
f t antilog 0.1 (L 90)
8
41
Knowledge in the Headnotions of internal
representation
42
Semantic Networks
Has Skin Can move Eats Breathes
ANIMAL
Can fly Has Wings Has feathers
BIRD
Has fins Can swim Has gills
FISH
Is Yellow Can sing
CANARY
Collins Quillian, 1969
43
Levels and Reaction time
A canary can sing
A canary can fly
A canary has gills
A canary has skin
Collins Quillian, 1969
A canary is a canary
A canary is a bird
A canary is a fish
A canary is an animal
44
Canaries
  • Different times to verify the statements
  • A canary is a bird
  • A canary can fly
  • A canary can sing
  • Time proportional to movement through network

45
  • Exercise 5
  • Define a chair

46
Concepts
  • How do you know a chair is a chair?

A chair has four legsdoes it? A chair has a
seatdoes it?
47
  • Exercise 6
  • On a scale of 1 (typical) to 7 (atypical), rate
    the following as examples of the concept
    FURNITURE
  • Chair Curtains
  • Sewing Machine Desk
  • Sofa Table
  • Telephone Vase
  • Dresser Fan
  • Clock Cooker

48
Prototypes, Typical Features, and Exemplars
  • Prototype
  • ROSCH (1973) people do not use feature sets, but
    imagine a PROTOTYPE for an object
  • Typical Features
  • ROSCH MERVIS (1975) people use a list of
    features, weighted in terms of CUE VALIDITY
  • Exemplars
  • SMITH MEDIN (1981) people use an EXAMPLE to
    imagine an object

49
Representing Concepts
  • BARSALOU (1983)
  • TAXONOMIC
  • Categories that are well known and can be
    recalled consistently and reliably
  • E.g., Fruit, Furniture, Animals
  • Used to generate overall representation of the
    world
  • AD HOC
  • Categories that are invented for specific purpose
  • E.g., How to make friends, Moving house
  • Used for goal-directed activity within specific
    event frames

50
CD Player
5-6 3-4 0-2
51
Propositional Network
52
Problems with Semantic and Propositional networks
  • Propositions do not have equal weight
  • Salmon is pink / has fins
  • Some items are more representative than others
  • Is bird Robin / Ibis
  • Some concepts do not have unequivocal defining
    attributes, e.g., game
  • Some items are fuzzy
  • Is furniture Chair / Book-end
  • Position in hierarchy does not always correspond
    to speed of response

53
Mental models
  • Craik
  • Internal representation of external reality
  • Every good monitor needs a model of the world it
    is monitoring
  • Johnson-Laird
  • Strategies of knowledge assimilation

54
Mental Models
  • Van Dijk and Kintsch (1983)
  • Text processed to extract propositions, which are
    held in working memory
  • When sufficient propositions in WM, then linking
    performed
  • Relevance of propositions to linking proportional
    to recall
  • Linking reveals gist

55
Scripts, Schema and Frames
  • Schema chunks of knowledge
  • Slots for information fixed, default, optional
  • Scripts action sequences
  • Generalised event schema (Nelson, 1986)
  • Frames knowledge about the properties of things

56
Mental Models
  • Partial
  • Procedures, Functions or System?
  • Memory or Reconstruction?

57
Session FivePerception
58
Data-driven perception
  • Activation of neural structures of sensory
    system by pattern of stimulation from environment

59
Theory-driven perception
  • Perception driven by memories and expectations
    about incoming information.

60
KEYPOINT
  • PERCEPTION involves a set of active processes
    that impose
  • STRUCTURE,
  • STABILITY,
  • and MEANING
  • on the world

61
Visual Illusions
http//www.genesishci.com/illusions2.htm
Rabbit or duck?
Old Woman or Young girl?
62
Exercise 7
i. X on outside front corner ii. X on
inside back corner
x
63
Exercise 7
  • Work on pairs Participant Observer
  • Participant Reverse X as fast as possible (say
    Reverse each time). Observer mark each reverse
  • Participant Fix X as front (say Reverse if X
    moves). Observer mark each reverse

64
KEYPOINT
  • Perception limits are set by sensory / neural
    mechanisms but beyond these limits, perception
    can be cognitively controlled
  • Sensory experiences interpreted in a CONTEXT and
    derive from a variety of sources

65
Designed to confuse?
Push the start button
66
Designed to confuse?
the start button
67
Marrs theory of visual perception
  • Primal Sketch
  • Viewer Centred Representation using basic
    perceptual properties, e.g., edges, length,
    contrast, contour
  • 2½D Sketch
  • Viewer Centred Representation using shading,
    texture, depth cues, figure-ground discrimination
  • 3D Sketch
  • Object Centred Representation using structural
    description of object independent of viewpoint

68
Primal Sketch Processes
69
2½D Sketch
  • Figure-ground segregation
  • Determine foreground and background
  • Depth perception
  • Monocular
  • Linear perspective
  • Texture gradients
  • Binocular
  • Motion parallax
  • Correspondence and Convergence

70
Contrast Effects
This text is quite easy to read because the
contrast between figure and ground is high
This text is more difficult to read because the
contrast between figure and ground is lower
This text is very hard to read because the
contrast between figure and ground is minimal
71
Pandemoniuma model of featureextractionLinds
ay and Norman, 1977
72
KEYPOINT
  • The design of displayed information INFLUENCES
    how the user can use that information
  • The design of displayed information should
    support EXTRACTION of relevant information

73
Reading
  • Saccades and Fixations
  • Anticipation and Inferences
  • Interpretation

74
Saccades and Fixations
75
Times for Normal Readers
  • Reading speed 180 350 wpm
  • Saccade 40ms
  • Return sweep 55ms
  • Fixation 330ms
  • 64 of words fixated
  • Perceptual span
  • 4 letters X 12 letters

76
Buffers Times for Reading
  • ms
  • 0 100 200 300 400
  • Photoreceptor stimulation
  • Iconic memory
  • Conceptual buffer
  • Articulatory loop
  • Visual spatial scratch pad
  • Central executive
  • Articulation

From Kintsch, W., 1998, Comprehension
77
Model of reading activity
Visual stimulus
Visual Analysis
Vpres
Grapheme-phoneme Correspondence rules
Mental lexicon
Apres
78
Interpretation
  • Knowledge of what you are looking at can aid
    in interpretation
  • JA CKAN DJI
  • LLW ENTU PTH
  • EHI LLT OFE
  • TCH APA ILO
  • FWA TER
  • Organisation of information is also useful

79
Story Grammars
  • Analogy with sentence grammars
  • Building blocks and rules for combining
  • Break story into propositions
  • Margie was holding tightly to the string of
    her beautiful new balloon. Suddenly a gust of
    wind caught it, and carried it into a tree. It
    hit a branch, and burst. Margie cried and cried.

80
Story Grammar
Story
Episode
Setting
1
Reaction
Event
Internal response
Overt response
Event
Event
6
Event
Event
Event
Event
sadness
4
3
2
Change Of state
5
81
Inferences
  • Comprehension typically requires our active
    involvement in order to supply information which
    is not explicit in the text
  • 1. Mary heard the ice-cream van coming
  • 2. She remembered her pocket money
  • 3. She rushed into the house.

82
Inference and Recall
  • Thorndyke (1976) recall of sentences from Mary
    story
  • 85 correct sentence
  • 58 correct inference
  • sentence not presented
  • 6 incorrect inference

83
Session FiveAttention
84
Stroop Task
  • name the colours in which these words are printed
    as quickly as possible

Stroop, 1935
85
Yellow
86
Blue
87
Red
88
Green
89
Blue
90
Yellow
91
Green
92
Conclusion
  • Reading words vs Naming colours
  • INTERFERENCE

93
Automatic vs Controlled
  • Automatic Processes are highly autonomous
  • Controlled Processes require conscious effort,
    i.e., need us to pay attention

94
Topics relating to attention
Eysenck and Keane, 1990
95
Focused Attention
  • Focused Attention
  • Present two stimuli and only respond to one
  • How can we follow one conversation when several
    people are speaking at once? (e.g., at a party)
  • Physical characteristics of message
  • Intensity of voice, gender of speaker

96
Shadowing
  • Listen to one message to each ear. Repeat back
    one message and ignore the other
  • listeners could not report the language used in
    the non-attended message
  • Listeners could not report content of the
    non-attended message even when words repeated 35
    times each
  • BUT if a tone was inserted into the non-attended
    message, listeners would notice it

97
Models of Selection
Selective filter
Sensory register
Short term memory
Perceptual process
Broadbent Triesman Deutsch and Deutsch
Sensory register
Attenuation control
Short term memory
Perceptual process
Sensory register
Selective filter
Perceptual process
Short term memory
98
Early SelectionBroadbent (1958)
Ring tone Altering, Distracting
S1
S2
Selection based on physical properties of stimulus
Limited Capacity Processing ignore other'
channel
99
Iconic MemorySperling (1960)
B F H K D C J M T R P N
100
Iconic MemorySperling (1960)
B F H K D C J M T R P N
101
Iconic MemorySperling (1960)
items reported 100 50 0
Partial report
Whole report
0 250 500 T (ms)
102
Problems with Early Selection
  • Gray and Wedderburn (1960)
  • Left ear Right ear
  • 6 AUNT 3 DEAR 8 JANE
  • Should report Left ear then Right ear, but
    participants reported Words then Numbers

103
AttenuationTreisman (1964)
  • People do not ignore unattended channel
  • All information undergoes superficial semantic
    analysis to determine relevance
  • If information not relevant, then processing
    attenuated

104
Unattended Channel?
  • Cherry (1953) claimed people do not attend to
    other channel, Treisman (1964) claims they do.
  • Cherry off-line measurement
  • Participants asked to report at the end of study
  • Treisman on-line measurement
  • Participants asked to report during study.
  • Reporting only occurs when short time between
    listening and report, i.e., a few seconds

105
Space-based Theories of Attention
  • spotlight metaphor
  • 0.5 degree minimal constriction
  • Loss of efficiency with size
  • Circular shape
  • Single spotlight (but can be divided into two)
  • Functions most effectively with fixation

106
Contemporary theories of attention
  • Object-based theories
  • People can select one of two overlapping objects
  • Neisser
  • Selection guided by Schema, following a
    Perceptual Cycle
  • Humphreys
  • Attentional Engagement theory
  • Perceptual description gt visual short term store

107
Subliminal Adverts
  • Canadian cinema goers had Drink Coke and Eat
    popcorn spliced into film sales increased
  • In 1990s
  • Study One participants shown spliced film and
    reported being more hungry / thirsty than control
  • Study Two same results only message said
    Phone now
  • See also self-help tapes, e.g., 50 of
    listeners in one study felt their memory had
    improved, but has listened to a different tape

108
Divided Attention
  • Dual tasks require people to divide attention
  • Limited attentional resource that is shared
    between tasks
  • Depends on tasks, e.g., talk and drive, sight
    read music and shadow speech

109
Allport et al. (1972)
  • Participants presented with essay, either visual
    and auditory
  • Recognition test far worse with auditory

Errors in Recognition ()
110
Brooks (1968)
F
  • Imagine F with moving around edge
  • When reaches junction or end, indicate Y (end)
    or N (junction)
  • Verbal say Yes or No
  • Tapping tap once for Y and twice for N
  • Pointing point to next Y or N in list
  • V T lt P
  • Indicating selective interference

111
Task Similarity
  • Interference when use same stimulus modality
    visual or auditory
  • Interference when use same stage of processing
    input central output
  • Interference when use same memory codes verbal
    or visual
  • Interference when use same response codes
    spoken or manual

112
Practice and Expertise
  • Highly practised dual-task performance, e.g., 6
    weeks read take dictation
  • Expert pianists can sight-read shadow expert
    typists can touch-type shadow
  • Performance strategies
  • Reduced demand
  • Reduced resource load

113
Automaticity
  • Norman and Shallice (1980)
  • Fully automatic processing controlled by SCHEMATA
  • Partially automatic processing controlled by
    either Contention Scheduling
  • Supervisory Attentional System (SAS)

114
Supervisory Attentional System Model
Supervisory Attentional System
Control schema
Trigger database
Perceptual System
Effector System
Contention scheduling
115
Contention Scheduling
  • Gear changing when driving involves many routine
    activities but is performed automatically
    without conscious awareness
  • When routines clash, relative importance is used
    to determine which to perform Contention
    Scheduling
  • e.g., right foot on brake or clutch

116
SAS activation
  • Driving on roundabouts in France
  • Inhibit look right Activate look left
  • SAS to over-ride habitual actions
  • SAS active when
  • Danger, Choice of response, Novelty etc.

117
Attentional Slips and Lapses
  • Habitual actions become automatic
  • SAS inhibits habit
  • Perserveration
  • When SAS does not inhibit and habit proceeds
  • Distraction
  • Irrelevant objects attract attention
  • Utilisation behaviour patients with frontal lobe
    damage will reach for object close to hand even
    when told not to

118
Performance Operating Characteristics
  • Resource-dependent trade-off between performance
    levels on two tasks
  • Task A and Task B performed several times, with
    instructions to allocate more effort to one task
    or the other

119
Task Difficulty
  • Data limited processes
  • Performance related to quality of data and will
    not improve with more resource
  • Resource limited processes
  • Performance related to amount of resource
    invested in task and will improve with more
    resource

120
POC
P
P
M
Cost
Cost
Task A
Task A
M
Task B
Task B
  • Data limited
  • Resource limited

121
Session FiveMemory
122
What is memory?
  • Is memory a permanent store of everything we
    know?
  • Why do we forget?
  • Why do we make mistakes when trying to remember
    something?
  • Why do we find we cant remember something and
    then suddenly remember it much later?

123
Recognition vs Recall
  • Recall
  • Retrieve from memory
  • Remembering the correct print command
  • Recognise
  • To bring back into awareness through prompt
  • Recognising print icon
  • Recognising print item in menu

124
Recall
  • Generate possible items, decide appropriateness
  • Direct match between information available and
    long-term memory

125
2 x 2 processes?
  • Contemporary thinking on recall / recognition
    implies at least two recall processes and at
    least two recognition processes
  • Selection of which process could reflect choice
    of STRATEGY

126
Recognition
  • Familiarity
  • Intra-item organisation
  • Effects sense of being to remember
  • Identification
  • Retrieval process
  • Recognition memory better for rare words than for
    common words (Gregg, 1976)

127
Encoding Specificity Principle
  • Recall and recognition different effects of same
    retrieval process
  • Retrieval depends on overlap between features in
    memory and features in retrieval environment
  • Vary Interactive context
  • Recall lt Cued recall lt Recognition

128
Long Term Memory
  • Procedural
  • Knowing how
  • Declarative
  • Knowing that
  • Episodic vs. Semantic
  • Personal events
  • Language and knowledge of world

129
Production Systems
  • Knowing how to do X
  • Production rule set of conditions and an action
  • IF it is raining
  • And you wish to go out
  • THEN pick up your umbrella

130
Declarative memory
  • Knowledge for facts
  • How is this knowledge organised?

131
Adaptive Control of Thought (ACT)
  • Network of propositions
  • Production rules selected via pattern matching
  • If information in working memory matches
    production rule condition, then fire production
    rule

132
ACT
Declarative memory
Procedural memory
Retrieval Storage Match Execution
Working memory
Encoding Performance
OUTSIDE WORLD
133
Retrieval from LTM
  • Forgetting
  • Recall vs. Recognition

134
Forgetting
  • Encoding failure
  • Failure of consolidation
  • Storage failure
  • Disruption by new or existing information
  • Associative interference
  • Two responses associated with same stimulus
  • Retrieval failure

135
Retrieval Failure
  • Context
  • Intrinsic / Interactive integral to stimulus
  • Extrinsic / Non-interactive appear during
    presentation but not part of stimulus
  • Environment
  • Classroom learning affected when testing took
    place in different room and reduced further in
    presence of different teacher
  • State
  • Affect of drugs on memory task show
  • Affect for free-recall when matched
  • No affect for cued recall or recognition

136
Amnesia 1
  • Infantile amnesia
  • Inability to remember events from before aged 4
    years
  • Anterograde amnesia
  • Inability to remember new information
  • HM learnt handful of words since 1950
  • Retrograde amnesia
  • Inability to remember events from just before
    injury / illness
  • Ribots law person aged 60 can remember
    childhood events and early adult life, but
    increasingly vague for later life

137
Amnesia 2
  • Evidence that declarative knowledge affected but
    procedural knowledge intact
  • Amnesiacs find it difficult to form new episodic
    or semantic memories
  • Amnesiacs often acquire motor skills as fast as
    normals

138
Exercise 3
139
Exercise 3.1
  • I will read a list of 20 words, when I have
    finished, write down as many as you can remember.
    You can write the words down in any order.

140
Exercise 3.2
  • I will read a list of 20 words, when I have
    finished write down as many as you can. You can
    write the words down in any order.

141
Exercise 3.3
  • I will give you a number, when you hear the
    number begin to count backwards in 3s, e.g., 99
    96 93, as quickly as you can. I will read a
    list of 20 words, when I have finished write down
    as many as you can. Do not stop counting in 3s.
    Write down the number you got to.

142
Working Memory
  • Limited Capacity
  • 7 2 items (Miller, 1965)
  • 4 2 chunks (Broadbent, 1972)
  • Modality dependent capacity
  • Strategies for coping with limitation
  • Chunking
  • Interference
  • Activation of Long-term memory

143
Baddeleys (1986) Model of Working Memory
Central executive
Visual Cache
Inner scribe
Phonological store
Auditory word presentation
Visual word presentation
Articulatory control process
144
Slave Systems
  • Articulatory loop
  • Memory Activation
  • Rehearsal capacity
  • Word length effect and Rehearsal speed
  • Visual cache
  • Visual patterns
  • Complexity of pattern, number of elements etc
  • Inner scribe
  • Sequences of movement
  • Complexity of movement

145
Cowan (1999) Embedded Processes Model of Working
Memory
146
Schematic of Cowans (1995)embedded processes
model
Central Executive
Long-term store
Controlled action
Automatic action
Activated memory
Brief sensory store
147
Cowans (1995) model
  • Working memory mechanism for activation of
    relevant long-term memory and for directing
    attention

148
Keypoint 6
  • Working memory is a volatile storage medium.
  • Do not expect people to remember complex
    information, particularly if they are doing
    something else at the same time.
  • Design information to keep within memory limits,
    e.g., no more than 9 items to a list

149
Session Four Skill Expertise
150
Varieties of Skill
  • Simple vs. Complex
  • Type of task
  • Physical vs. Cognitive
  • Demands and resources
  • Open vs. Closed Loop
  • Interaction with stimuli
  • Controlled vs. Automatic
  • Demands on attentional capacity

151
Classification of skills Holding (1989)
Complex
ATC violin sleight-of-hand
DECISION
TRACKING
football piloting sailing draughting ballet
Closed (Motor, Habitual, Automatic)
Open (Perceptual, Controlled, Skilled)
TAPPING
VIGILANCE
detection sorting shot-putting
Simple
152
Reaction Time
  • Time to respond to a stimulus
  • Speed-accuracy trade-off
  • Proficiency requires response on time

153
Choice Reaction Time
  • Hick-Hyman Law (1952)
  • CRT K log (n 1)
  • CRT choice reaction time, K constant (equal
    to SRT), and n number of alternatives
  • Smith (1977)
  • CRT K log (n C/E 1)
  • C response emphasis ( c speed or C accuracy),
    E strength of stimulus

154
Expert Reaction Time
  • Timing requires anticipation of stimulus to
    offset response delay
  • Skill as ability to anticipate events and to
    produce, quickly, appropriate chain of responses

155
Acquiring Skill
  • Fitts (1962)
  • Cognitive phase
  • instructions and practice with knowledge of
    results
  • Associative phase
  • practice to criterion and self-monitoring
  • Autonomous phase
  • automated performance

156
Practice
  • Skilled performance lacks asymptote
  • Physical limitations of task or decline in
    capabilities, due to fatigue of ageing as
    limiting factors
  • Thus, increased experience leads to increased
    performance
  • Goalkeeping relative to judging speed and angle
    of shots rather than physical fitness
  • Professional snooker, darts or golf players
    compete into their forties and beyond

157
Feedback
  • Prior to action
  • Anticipation / prompts
  • During action
  • Intrinsic
  • Kinaesthetic
  • Proprioception
  • Extrinsic
  • Post action
  • Knowledge of results

158
Typing
  • Eye-hand span related to expertise
  • Expert 9, novice 1
  • Inter-key interval
  • Expert 100ms
  • Strategy
  • Hunt Peck vs. Touch typing
  • Keystroke
  • Novice highly variable keystroke time
  • Novice very slow on unusual letters, e.g., X
    or Z

159
Salthouse (1986)
  • Input
  • Text converted to chunks
  • Parsing
  • Chunks decomposed to strings
  • Translation
  • Strings into characters and linked to movements
  • Execution
  • Key pressed

160
Rumelhart Norman (1982)
  • Perceptual processes
  • Perceive text, generate word schema
  • Parsing
  • Compute codes for each letter
  • Keypress schemata
  • Activate schema for letter-keypress
  • Response activation
  • Press defined key through activation of
    appropriate hand / finger

161
Schematic of Rumelhart and Normans connectionist
model of typing
middle ring index little
thumb Left hand
middle index ring thumb
little Right hand
Response system
Keypress node, breaking Word into typed
letters Excites and inhibits nodes
z
z
j
a
activation
Word node, activated from Visual or auditory
stimulus
jazz
162
Conclusions
163
Key point 1
  • A User model for designers assumes that people
    actively seek information from the environment
    and develop expectations of how things work
    these expectations influence the ways in which
    people seek information.

164
Schematic of Rumelhart and Normans connectionist
model of typing
middle ring index little
thumb Left hand
middle index ring thumb
little Right hand
Response system
Keypress node, breaking Word into typed
letters Excites and inhibits nodes
z
z
j
a
activation
Word node, activated from Visual or auditory
stimulus
jazz
165
Keypoint 2
  • In order to learn the correct view, it is
    necessary to undo the incorrect view
  • This means that acquiring new knowledge might
    mean effortfully removing erroneous, old
    knowledge

166
Key point 3
  • PERCEPTION involves a set of active processes
    that impose
  • STRUCTURE,
  • STABILITY,
  • and MEANING
  • on the world

167
Key point 4
  • Perception limits are set by sensory / neural
    mechanisms but beyond these limits, perception
    can be cognitively controlled
  • Sensory experiences interpreted in a CONTEXT and
    derive from a variety of sources

168
Supervisory Attentional System Model
Supervisory Attentional System
Control schema
Trigger database
Perceptual System
Effector System
Contention scheduling
169
Key point 5
  • The design of displayed information INFLUENCES
    how the user can use that information
  • The design of displayed information should
    support EXTRACTION of relevant information

170
Working Memory
Central Executive
Visuo-spatial scratchpad
Phonological Loop
Auditory word presentation Visual word
presentation Articulatory programmes
Visual cache Inner scribe
171
Keypoint 6
  • Working memory is a volatile storage medium.
  • Do not expect people to remember complex
    information, particularly if they are doing
    something else at the same time.
  • Design information to keep within memory limits,
    e.g., no more than 9 items to a list

172
Solutions to Exercisesand Problems
173
Exercise Two
174
Problem 1
175
Problem 2
  • 2.64
  • 14)37

176
Problem3
  • 9567
  • 1085
  • 10652

177
Exercise .1
  • 1. Apple 2. North 3. Charlie 4. Nickel 5. Red
  • 6. Banana 7. South 8. Fred 9. Cent 10. Green
  • 11. Pear 12. East 13. George 14. Dime 15. Yellow
  • 16. Grape 17. Wayne 18. Dave 19. Penny 20. Blue
  • Make a note of the word numbers and enter into
    table
  • How many people wrote West or Orange?
  • What pattern do you notice in the words?

178
Exercise .2
  • 1. Latch 2. Bream 3. Hot 4. Mayor 5. Jab
  • 6. Busk 7. Else 8. Wage 9. Clog 10. Jowl
  • 11. Chap 12. Big 13. Smug 14. Duck 15. Trout
  • 16. Blot 17. Reek 18. Tape 19. List 20. Skirt
  • Make a note of the word numbers and enter into
    table
  • What pattern do you notice in the words?
  • Did you do as well as with the first list?

179
Exercise .3
  • 1. Time 2. House 3. Mit 4. Stab 5. Solve
  • 6. Draft 7. Say 8. Off 9. Boil 10. Court
  • 11. Greet 12. Slot 13. Hand 14. Dirt 15. Clot
  • 16. Stale 17. Out 18. Dumped 19. Stone 20. Dice
  • Make a note of the word numbers and enter into
    table
  • Did you do as well as with the other lists?
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