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Human Abilities. Sensory, motor, and cognitive capabilities. Outline. Last week’s example: my thoughts Scenario discussion Human capabilities Senses Motor systems Information processing Memory Cognitive Processes Selective attention, learning, problem solving, language. - PowerPoint PPT Presentation
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Outline
Last week’s example: my thoughts Scenario discussion Human capabilities
– Senses– Motor systems– Information processing
Memory Cognitive Processes
– Selective attention, learning, problem solving, language
Movie Ticket Kiosk: my thoughts
Data gathering methods:– 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
Stakeholders:– Primary: ticket buyer– Secondary: those with the ticket buyer, theater owners/managers– Tertiary: theater employees, movie makers– Facilitating: us
User characteristics:– Wide range of ages and abilities– Wide range of education and comfort levels
Although will target basic English reading levels and computer comfort– Want entertainment, no hassle and pressure
Movie Ticket Kiosk
Physical environment:– Indoor or outdoor– Busy, crowded and noisy area– Will be lines of people forming
Technical environment:– Need to integrate with movie/showings database and credit card
system Social environment:
– 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.
Typical scenario of use:– 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 Atypical scenario of use:
– 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
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.
Basic Human Capabilities
Do not change very rapidly– Not like Moore’s law!
Have limits, which are important to understand Our abilities do not change, but our understanding
of them does Why do we care?
– Better design!– Want to improve user performance
Universal design – design for everyone, including those with disabilities
– 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
– 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?– ideally, yes– practically – no
We can use • sight • sound • touch (sometimes)
We cannot (yet) use • taste • smell
Vision Fundamentals
Retina has– 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– Switching between dark and
light causes fatigue
Vision implications (more to come in visual design)
Color– Distinguishable hues, optical illusions– About 9 % of males are red-green colorblind!– See http://colorlab.wickline.org/colorblind/colorlab/
Acuity– Determines smallest size we can see– Less for blue and yellow than for red and green
Color/Intensity Discrimination
The 9 hues most people can identify are:Color WavelengthRed 629Red-Orange 596Yellow-Orange 582Green-Yellow 571Yellow-Green 538Green 510Blue-Green 491
Blue 481
Violet-Blue 460
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)
Capabilities (best-case scenario)– pitch - frequency (20 - 20,000 Hz)– loudness - amplitude (30 - 100dB)– location (5° source & stream separation)– timbre - type of sound (lots of instruments)
Often take for granted how good it is(disk whirring)
Implications ?
Design implications
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
Three main sensations handled by different types of receptors:
– Pressure (normal)– Intense pressure (heat/pain)– Temperature (hot/cold)
Where important?– Mouse, Other I/O, VR, surgery
Motor System (Our Output System)
Capabilities– Range of movement, reach, speed,
strength, dexterity, accuracy– Workstation design, device design
Often cause of errors– Wrong button– Double-click vs. single click
Principles– Feedback is important– Minimize eye movement
See Handbooks for data
The “Model Human Processor”
A true classic - see Card, Moran and Newell, The Psychology of Human-Computer Interaction, Erlbaum, 1983
– 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)– Neglects effect of other people
Memory
Perceptual “buffers”– Brief impressions
Short-term (working) memory– Conscious thought, calculations
Long-term memory– Permanent, remember everything that ever
happened to us
LONG-TERM MEMORY
SHORT-TERM (WORKING) MEMORY
AUDITORY IMAGESTORE
VISUAL IMAGESTORE
R = SemanticD = InfiniteS = Infinite
R = AcousticD = 1.5 [0.9-3.5] sS = 5 [4.4-6.2] letters
R = VisualD = 200 [70-1000] msS = 17 [7-17] letters
R= Acoustic or VisualD (one chunk) = 73 [73-226] sD (3 chunks) = 7 [5-34] sS = 7 [5-9] chunks
R = RepresentationD = Decay TimeS = SizeC = Cycle Time
PERCEPTUALPROCESSOR
C = 100 [5-200] ms
COGNITIVEPROCESSOR
C = 70 [27-170] ms
MOTORPROCESSOR
C = 70 [30-100] MS
Eye movement (Saccade) = 230 [70-700] ms
Sensory Stores
Very brief, but accurate representation Physically encoded Limited capacity
– Iconic: 7-17 letters– Echoic: 4-6– Haptic: ??
Rapid Decay– 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
– Pattern recognition, language, etc.
Short Term Memory
Symbolic, nonphysical acoustic or visual coding
Somewhat limited capacity– 7 +- 2 “chunks” of information
Slower decay– 5-226 sec– rehearsal prevents decay
Another task prevents rehearsal - interference
About Chunks
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
– User and task dependent
Implications?
Which is an implication of 7 +- 2?– 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
Semantic storage Seemingly permanent & unlimited Access is harder, slower
– -> 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
Episodic memory– Events & experiences in serial form
Helps us recall what occurred
Semantic memory– Structured record of facts, concepts & skills
One theory says it’s like a network Another uses frames & scripts (like record structs)
Memory Characteristics
Things move from STM to LTM by rehearsal & practice and by use in context
– 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– Similar gets in the way
Recognition over Recall
We recognize information easier than we can recall information
Examples? Implications?
Processes
Four main processes of cognitive system:– Selective Attention– Learning– Problem Solving– Language
Selective Attention
We can focus on one particular thing– Cocktail party chit-chat
Salient visual cues can facilitate selective attention– Examples?
Learning
Two types:– Procedural – How to do something– Declarative – Facts about something
Involves– Understanding concepts & rules– Memorization– Acquiring motor skills– Automotization
Tennis Driving to work
– Even when don’t want to Swimming, Bike riding, Typing, Writing
Learning
Facilitated– By structure & organization– By similar knowledge, as in consistency in UI design– By analogy– If presented in incremental units– Repetition
Hindered– By previous knowledge
Try moving from Mac to Windows
=> Consider user’s previous knowledge in your interface design
Observations
Users focus on getting job done, not learning to effectively use system
Users apply analogy even when it doesn’t apply– Or extend it too far - which is a design problem
Dragging floppy disk icon to Mac’s trash can does NOT erase the disk, it ejects disk!
Problem Solving
Storage in LTM, then application Reasoning
– Deductive – If A then B– Inductive - Generalizing from previous
cases to learn about new ones– Abductive - Reasons from a fact to the
action or state that caused it
Goal in UI design - facilitate problem solving!
– How??
Observations
We are more heuristic than algorithmic– We try a few quick shots rather than plan
Resources simply not available
We often choose suboptimal strategies for low priority problems
We learn better strategies with practice
Implications
Allow flexible shortcuts– Forcing plans will bore user
Have active rather than passive help– Recognize waste
Language
Rule-based– How do you make plurals?
Productive– We make up sentences
Key-word and positional– Patterns
Should systems have natural language interfaces?– 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
Good1. xxx
2. yyy
3. zzz
Bad1. aaa
2. bbb
3. ccc
Fill in the columns - what are people good at and what are people bad at?
People
Good– Infinite capacity LTM– LTM duration & complexity– High-learning capability– Powerful attention
mechanism– Powerful pattern recognition
Bad– Limited capacity STM– Limited duration STM– Unreliable access to LTM– Error-prone processing– Slow processing