human abilities sensory and cognitive capabilities
TRANSCRIPT
Human Abilities
Sensory and cognitive capabilities
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
Typical Person
Do we really have limited memory capacity?
Outline
Questions? Human capabilities Memory and cognitive processes Predictive models
Basic Human Capabilities
Do not change very rapidly– Not like Moore’s law!
Have limits, which are important to understand
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 (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 Surround Effect
Our perception of a color is affected by the surrounding color
Which is easiest to read and why?
What is the time?
What is the time?
What is the time?
What is the time?
What is the time?
From http://www.id-book.com
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(error beeps, disk whirring)
Implications ?
Attention
Involves audio and/or visual senses
Selecting things to concentrate on from the mass of stimuli around us
Focused and divided attention enables us to be selective but limits our ability to keep track of all events
Structure information to capture users’ attention perceptual boundaries (windows), color, reverse video,
sound and flashing lights From http://www.id-book.com
Activity: Find the price of a double room at the Holiday Inn in Bradley
From http://www.id-book.com
Activity: Find the price for a double room at the Quality Inn in Columbia
From http://www.id-book.com
Activity
Tullis (1987) found that the two screens produced quite different results
– 1st screen - took an average of 5.5 seconds to search– 2nd screen - took 3.2 seconds to search
Why, since both displays have the same density of information (31%)?
Spacing– In the 1st screen the information is bunched up together, making it
hard to search– In the 2nd screen the characters are grouped into vertical
categories of information making it easier
From http://www.id-book.com
Design implications
Representations of information need to be perceptible and recognizable
Make information salient when it needs attending to– Make things stand out with colour, ordering, spacing,
underlining, sequencing and animation
Avoid cluttering the interface
Sounds should be audible and distinguishable Speech output should enable users to distinguish
between the set of spoken words
From http://www.id-book.com
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
What goes on in the mind?
Core cognitive aspects
Attention
Perception and recognition
Memory
Reading, speaking and listening
Problem-solving, planning, reasoning and decision-making, learning
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
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
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
Processing in memory
Attention filters information into memory and for more processing– The more attention paid to something,– And the more it is processed in terms of thinking
about it and comparing it with other knowledge, – The more likely it is to be remembered
Context is important– Difficult to remember things in another context
Activity
Try to remember the dates of your grandparents’ birthday
Try to remember the cover of the last two DVDs you bought or rented
Which was easiest? Why? People are very good at remembering visual cues
about things– e.g., the color of items, the location of objects and marks on an
object
They find it more difficult to learn and remember arbitrary material
– e.g., birthdays and phone numbersFrom http://www.id-book.com
Implications?
Which is an implication of 7 +- 2?– Use about 7 items on a menu– Display 7 icons on a task bar– No more than 7 tabs on a window– 7 bullets in a list
ALL WRONG!
Why?
Inappropriate application of the theory People can scan lists of bullets, tabs, menu items till
they see the one they want They don’t have to recall them from memory having
only briefly heard or seen them Sometimes a small number of items is good design
– But it depends on task and available screen, NOT memory
From http://www.id-book.com
Recognition over Recall
We recognize information easier than we can recall information
Examples? Implications?
Externalizing to reduce memory load
Reminders, calendars, notes, shopping lists, to-do lists - written to remind us of what to do
Post-its, piles, marked emails - where placed indicates priority of what to do
External representations:– Remind us that we need to do something (e.g. to buy
something for mother’s day)– Remind us of what to do (e.g. buy a card)– Remind us when to do something (e.g. send a card by a
certain date)
From http://www.id-book.com
Memory Summary
Involves encoding and then retrieving knowledge We don’t remember everything - involves filtering
and processing what is attended to Context is important in affecting our memory (i.e.,
where, when) Well known fact that we recognize things much
better than being able to recall things Also better at remembering images than words
– Why interfaces are largely visual
From http://www.id-book.com
Design implications
Don’t overload users’ memories with complicated procedures for carrying out tasks
Design interfaces that promote recognition rather than recall
Provide users with a variety of ways of encoding digital information to help them remember where they have stored them
– e.g., categories, color, flagging, time stamping
From http://www.id-book.com
Other processes: 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
Encourage exploration
Other Processes: Problem Solving
Users focus on getting job done, not learning to
effectively use system 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 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!
Implications
Help users accomplish main tasks Provide useful analogies Allow flexible shortcuts and multiple ways to
accomplish a task– Forcing plans will bore user
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
Example: Passwords
What’s wrong with computer passwords? How do people cope? How to banks, sites, etc. cope?
Suggested improvements:– Have a tool remember them all– How about visual passwords?– Eliminate the need – use biometrics
Reminder: Assignment
Task analysis due Monday
And get started on your Project Part 1!