Transcript Human Abilities

Human Abilities
Sensory, motor, and cognitive
capabilities
Outline
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Last week’s example: my thoughts
Scenario discussion
Human capabilities
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Senses
Motor systems
Information processing
Memory
Cognitive Processes
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Selective attention, learning, problem solving, language
Movie Ticket Kiosk: my thoughts
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Data gathering methods:
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Stakeholders:
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Observation of theater with and without kiosk
Observe several people up close using existing kiosks
Interview several movie owners and workers
A couple of focus groups of end users
Primary: ticket buyer
Secondary: those with the ticket buyer, theater owners/managers
Tertiary: theater employees, movie makers
Facilitating: us
User characteristics:
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Wide range of ages and abilities
Wide range of education and comfort levels
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Although will target basic English reading levels and computer comfort
Want entertainment, no hassle and pressure
Movie Ticket Kiosk
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Physical environment:
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Technical environment:
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Indoor or outdoor
Busy, crowded and noisy area
Will be lines of people forming
Need to integrate with movie/showings database and credit card
system
Social environment:
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Multiple people going to same movie, maybe buying tickets
together or on own
Some movies have age restrictions
Some people qualify for discounted tickets, but most don’t
Lines of people waiting to buy tickets – annoyance and social
pressure
Movie ticket kiosk, cont.
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Typical scenario of use:
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Atypical scenario of use:
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Know what movie and time, see line is long at person so use kiosk, select
the movie and show time, use credit card, get tickets
Movie was sold out, now have to decide what to see. Call group of people
back to kiosk to look through movies and show times to make decision.
Finally decide on different one and purchase tickets.
HTA: goal of going to a movie, subtasks such as look at movies out,
decide on movie and showtime, purchase tickets, enter theater.
ER diagram: objects such as movies, theaters, times, ticket, customer,
etc. HTA would probably be more useful
Flowchart: may be even better than HTA at representing task flow: look
at movies, desired movie? Then look at times. Desired time? If no,
look at movies again. If yes, decide on ticket type and how many
(student, regular, etc.). Purchase ticket.
Scenario
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Its Thursday afternoon and Pat has a blackboard quiz due on Friday.
This is her first class using blackboard. She sits down at her laptop to
take the quiz. She access the UNCC website then 49er express. After
logging on to 49er she sees the link to blackboard so she clicks on it. It
prompts her to log in again, she does not understand why she would
need to log in after already logging on to 49er, but she logs in even
though it’s a pain because she has to get this quiz done. Then she
gets an error message from blackboard that it must use pops up to
work properly, Pat did not install the blocker and does not know how to
disable it. Now she is realizing its crunch time and she must get this
quiz done. She heads off for the library where she must access 49er
express again. She then tries to access blackboard again to find out
she must log in again, she again is confused as why she must log in
twice but does so without questioning it because she must get this quiz
taken. Finally she is able to get on blackboard and take her quiz, she
feels very upset about logging on multiple times and blackboard not
working on her computer.
Typical Person
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Do we really have limited memory capacity?
Basic Human Capabilities
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Do not change very rapidly
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Have limits, which are important to understand
Our abilities do not change, but our understanding
of them does
Why do we care?
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Not like Moore’s law!
Better design!
Want to improve user performance
Universal design – design for everyone, including
those with disabilities
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We’ll come back to this later in the semester…
Usable Senses
The 5 senses (sight, sound, touch, taste and smell) are used by us
every day
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each is important on its own
together, they provide a fuller interaction with the natural world
Computers rarely offer such a rich interaction
Can we use all the available senses?
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ideally, yes
practically – no
We can use
• sight • sound • touch (sometimes)
We cannot (yet) use
• taste • smell
Vision Fundamentals
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Retina has
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6.5 M cones (color vision),
mostly at fovea (1/3)˚
About 150,000 cones per
square millimeter
Fewer blue sensing cones
than red and green at fovea
100 M rods (night vision),
spread over retina, none at
fovea
Adaptation
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Switching between dark and
light causes fatigue
Vision implications (more to come in visual
design)
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Color
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Distinguishable hues, optical illusions
About 9 % of males are red-green colorblind!
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See http://colorlab.wickline.org/colorblind/colorlab/
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Acuity
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Determines smallest size we can see
Less for blue and yellow than for red and green
Color/Intensity Discrimination
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The 9 hues most people can identify are:
Color
Red
Red-Orange
Yellow-Orange
Green-Yellow
Yellow-Green
Green
Blue-Green
Blue
Violet-Blue
Wavelength
629
596
582
571
538
510
491
481
460
Color Surround Effect
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Our perception of a color is affected by the
surrounding color
Effect of Colored Text on Colored
Background
Black text on white
Gray text on white
Yellow text on white
Light yellow text on white
Green text on white
Light green text on white
Blue text on white
Pale blue text on white
Dark red text on white
Red text on white
Rose text on white
Audition (Hearing)
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Capabilities (best-case scenario)
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pitch - frequency (20 - 20,000 Hz)
loudness - amplitude (30 - 100dB)
location (5° source & stream separation)
timbre - type of sound (lots of instruments)
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Often take for granted how good it is
(disk whirring)
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Implications ?
Design implications
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Representations of information need to be
designed to be perceptible and recognizable
Icons and other graphical representations should
enable users to readily distinguish their meaning
Bordering and spacing are effective visual ways of
grouping information
Sounds should be audible and distinguishable
Speech output should enable users to distinguish
between the set of spoken words
Text should be legible and distinguishable from the
background
Touch
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Three main sensations handled
by different types of receptors:
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Pressure (normal)
Intense pressure (heat/pain)
Temperature (hot/cold)
Where important?
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Mouse, Other I/O, VR, surgery
Motor System (Our Output
System)
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Capabilities
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Often cause of errors
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Wrong button
Double-click vs. single click
Principles
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Range of movement, reach, speed,
strength, dexterity, accuracy
Workstation design, device design
Feedback is important
Minimize eye movement
See Handbooks for data
Work Station Ergonomics – to
Facilitate I/O
The Mind
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And now on to memory and cognition…
The “Model Human Processor”
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A true classic - see Card, Moran and Newell, The
Psychology of Human-Computer Interaction,
Erlbaum, 1983
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Microprocessor-human analogue using results from
experimental psychology
Provides a view of the human that fits much experimental
data
But is a partial model
Focus is on a single user interacting with some entity
(computer, environment, tool)
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Neglects effect of other people
Memory
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Perceptual “buffers”
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Short-term (working) memory
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Brief impressions
Conscious thought, calculations
Long-term memory
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Permanent, remember everything that ever
happened to us
LONG-TERM MEMORY
R = Semantic
D = Infinite
S = Infinite
SHORT-TERM (WORKING) MEMORY
VISUAL IMAGE
STORE
R = Visual
D = 200 [70-1000] ms
S = 17 [7-17] letters
AUDITORY IMAGE
STORE
R = Acoustic
D = 1.5 [0.9-3.5] s
S = 5 [4.4-6.2] letters
R= Acoustic or Visual
D (one chunk) = 73 [73-226] s
D (3 chunks) = 7 [5-34] s
S = 7 [5-9] chunks
PERCEPTUAL
PROCESSOR
COGNITIVE
PROCESSOR
MOTOR
PROCESSOR
C = 100 [5-200] ms
C = 70 [27-170] ms
C = 70 [30-100] MS
R = Representation
D = Decay Time
S = Size
C = Cycle Time
Eye movement (Saccade) = 230 [70-700] ms
Sensory Stores
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Very brief, but accurate representation
Physically encoded
Limited capacity
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Rapid Decay
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Iconic: 7-17 letters
Echoic: 4-6
Haptic: ??
Iconic: 70-1000 ms
Echoic: 0.9 – 3.5 sec
Attention filters information into short term memory and beyond
for more processing
Perceptual Processor – interpret signal into semantically
meaningful
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Pattern recognition, language, etc.
Short Term Memory
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Symbolic, nonphysical acoustic or visual
coding
Somewhat limited capacity
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Slower decay
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7 +- 2 “chunks” of information
5-226 sec
rehearsal prevents decay
Another task prevents rehearsal interference
About Chunks
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A chunk is a meaningful grouping of
information – allows assistance from LTM
4793619049 vs. 704 687 8376
NSAFBICIANASA vs. NSA FBI CIA NASA
My chunk may not be your chunk
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User and task dependent
Implications?
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Which is an implication of 7 +- 2?
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Use 5-9 items on a menu
Display 5-9 icons on a task bar
No more than 7 tabs on a window
5-9 items in a list
Long-Term Memory
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Semantic storage
Seemingly permanent & unlimited
Access is harder, slower
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-> Activity helps (we have a cache)
Retrieval depends on network of associations
How information is perceived, understood and
encoded determines likelihood of retrieval
File system full
LT Memory Structure
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Episodic memory
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Events & experiences in serial form
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Helps us recall what occurred
Semantic memory
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Structured record of facts, concepts & skills
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One theory says it’s like a network
Another uses frames & scripts (like record structs)
Memory Characteristics
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Things move from STM to LTM by rehearsal &
practice and by use in context
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Do we ever lose memory? Or just lose the link?
What are effects of lack of use?
We forget things due to decay and interference
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Similar gets in the way
Recognition over Recall
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We recognize information easier than we
can recall information
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Examples?
Implications?
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Processes
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Four main processes of cognitive system:
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Selective Attention
Learning
Problem Solving
Language
Selective Attention
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We can focus on one particular thing
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Cocktail party chit-chat
Salient visual cues can facilitate selective
attention
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Examples?
Learning
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Two types:
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Procedural – How to do something
Declarative – Facts about something
Involves
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Understanding concepts & rules
Memorization
Acquiring motor skills
Automotization
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Tennis
Driving to work
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Even when don’t want to
Swimming, Bike riding, Typing, Writing
Learning
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Facilitated
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By structure & organization
By similar knowledge, as in consistency in UI design
By analogy
If presented in incremental units
Repetition
Hindered
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By previous knowledge
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Try moving from Mac to Windows
=> Consider user’s previous knowledge in your
interface design
Observations
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Users focus on getting job done, not learning
to effectively use system
Users apply analogy even when it doesn’t
apply
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Or extend it too far - which is a design problem
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Dragging floppy disk icon to Mac’s trash can does NOT
erase the disk, it ejects disk!
Problem Solving
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Storage in LTM, then application
Reasoning
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Deductive – If A then B
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Inductive - Generalizing from previous
cases to learn about new ones
Abductive - Reasons from a fact to the
action or state that caused it
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Goal in UI design - facilitate problem solving!
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How??
Observations
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We are more heuristic than algorithmic
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We try a few quick shots rather than plan
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Resources simply not available
We often choose suboptimal strategies for
low priority problems
We learn better strategies with practice
Implications
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Allow flexible shortcuts
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Forcing plans will bore user
Have active rather than passive help
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Recognize waste
Language
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Rule-based
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Productive
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We make up sentences
Key-word and positional
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How do you make plurals?
Patterns
Should systems have natural language interfaces?
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Stay tuned
Recap
I. Senses
A. Sight
B. Sound
C. Touch
D. Smell
II. Information processing
A. Perceptual
B. Cognitive
1. Memory
a. Short term
b. Long term
2. Processes
a. Selective attention
b. Learning
c. Problem solving
d. Language
People
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Good
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xxx
yyy
zzz
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Bad
1.
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aaa
bbb
ccc
Fill in the columns what are people good at
and what are people
bad at?
People
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Good
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Infinite capacity LTM
LTM duration & complexity
High-learning capability
Powerful attention
mechanism
Powerful pattern recognition
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Bad
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Limited capacity STM
Limited duration STM
Unreliable access to LTM
Error-prone processing
Slow processing
Next Assignment: HTA
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Current activity that relates to your project
topic
Either create diagram and upload the file to
the Swiki
Or use the numbered outline approach
Don’t forget those plans!