Human Abilities Sensory, motor, and cognitive capabilities.
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Transcript of Human Abilities Sensory, motor, and cognitive capabilities.
Human AbilitiesSensory, motor, and cognitive capabilities
Outline
Human capabilities Senses Motor systems Information processing
Memory Cognitive Processes
Selective attention, learning, problem solving, language
Typical Person
Do we really have limited memory capacity?
Basic Human Capabilities
Do not change very rapidly Not like Moore’s law!
Have limits, which are important to understand
Our understanding of human capabilities does change, ie Cognitive neuroscience Theories of color perception Effect of groups and situation on how we act
and react
Human Capabilities
Why do we care? Better design! Want to improve user performance
Knowing the user informs the design Senses Information processing systems Physical responding
Senses (Our Input System)
Sight, hearing, touch important for current HCISmell, taste ???
Abilities and limitations affect design
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)
ColorDistinguishable hues, optical illusionsAbout 9 % of males are red-green
colorblind! Acuity
Determines smallest size we can seeLess 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
Color Surround Effect
Our perception of a color is affected by the surrounding color
Color Surround
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
Effect of Colored Text on Colored Background
Black text on red
Gray text on red
Yellow text on red
Light yellow text on red
Green text on red
Light green text on red
Blue text on red
Pale blue text on red
Dark red text on red
Red text on red
Rose text on red
Effect of Colored Text on Colored Background
Black text on dark blue
Gray text on dark blue
Yellow text on dark blue
Light yellow text on dark blue
Green text on dark blue
Light green text on dark blue
Blue text on dark blue
Pale blue text on dark blue
Dark red text on dark blue
Red text on dark blue
Rose text on dark blue
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 ?
Touch
Three main sensations handled by different types of receptors: Pressure (normal) Intense pressure (heat/pain) Temperature (hot/cold)
Sensitivity, Dexterity, Flexibility, Speed
Where important? Mouse, Other I/O, VR, surgery
Smell
Joseph Kaye, “Making scents: aromatic output for HCI” ACM Interactions Volume 10, Number 1 (2004), Pages 48-61
Solenoid-controlled scent bottles
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
Work Station Ergonomics – to Facilitate I/O
The Mind
And now on to memory and cognition…
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) memoryConscious thought, calculations
Long-term memoryPermanent, 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
Perceptual or Sensory Memory
Very brief, but accurate representation of what was perceived
Physically encoded Details decay quickly (70 - 1000 ms
visual; 0.9 - 3.5 sec auditory) Limited capacity (7 - 17 letters visual;
4 - 6 auditory)
Sensory Stores
Iconic – visual 7 - 17 letters; 70 - 1000 ms decay
Echoic – auditory 4 - 6 auditory; 0.9 - 3.5 sec auditory
Haptic - touch Attention filters information into short term memory
and beyond for more processing Processors – interpret signal into semantically
meaningful Pattern recognition, language, etc.
Short Term Memory
Use “chunks”: 7 +- 2 units of information
Symbolic, nonphysical acoustic or visual coding
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
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 memoryEvents & experiences in serial form
• Helps us recall what occurred
Semantic memoryStructured 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 AttentionLearningProblem SolvingLanguage
Selective Attention
We can focus on one particular thingCocktail party chit-chat
Salient visual cues can facilitate selective attentionExamples?
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 applyOr 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 -
Inductive -
Abductive -
Goal in UI design - facilitate problem solving! How??
If A, then B
Generalizing from previouscases to learn about new onesReasons from a fact to theaction or state that caused it
Observations
We are more heuristic than algorithmicWe 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 shortcutsForcing plans will bore user
Have active rather than passive helpRecognize 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. Medium term c. Long term 2. Processes a. Selective attention b. Learning c. Problem solving d. Language
III. Motor system A. Hand movement B. Workstation Layout
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
Class Discussion:Model Human Processor
What are the three major subsystems and their functions? What does it mean to say that certain subprocessors have
“variable rates?” What are some of the other assumptions underlying the
MHP model? How good is the model?
Scenarios
Make sure it is a story withActors (at least one person)Actions (not just the context)
Good focus on the negativeTry to follow through with what the
person does