ITM 734 Introduction to Human Factors in Information Systems Cindy Corritore [email protected] This...

ITM 734Introduction to Human Factors in Information Systems

Cindy [email protected]

This material has been developed by Georgia Tech HCI faculty, and continues to evolve.

Human Abilities: Cognitive Abilities

ITM 734 (Corritore) 2

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


The “Model Human Processor”

• A true classic - see Card, Moran and Newell, The Psychology of Human-Computer Interaction, Erlbaum, 1983 Microprocessor–human analog using

results from experimental psychology Provides a view of the human that fits

much experimental data


Block Diagram - Model Human Processor (MHP)

LONG-TERM MEMORY

SHORT-TERM (WORKING) MEMORY

AUDITORY IMAGESTORE

VISUAL IMAGESTORE

PERCEPTUALPROCESSOR

COGNITIVEPROCESSOR

MOTORPROCESSOR


MHP is not Complete

• Only two senses Certainly the most important

• Focus is on a single user interacting with some entity (computer, environment, tool) Neglects effect of other people


Three Processors

• Perceptual Processor• Cognitive Processor• Motor Processor

• Each has a cycle time (average and range), determined experimentally Represented by C


Block Diagram - MHP – Three Processors, Cycle Times

LONG-TERM MEMORY


AUDITORY IMAGESTORE

VISUAL IMAGESTORE

C = Cycle Time [Range]

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


Through all of this ….

• limited cognitive resources/load (memory load) analogy flawed plans (heuristics) simulations (cognitive/mental models)

• goal – to minimize complexity through improved fit (between user, computer, and task)


Block Diagram – MHP – Three Memories

LONG-TERM MEMORY


AUDITORY IMAGESTORE

VISUAL IMAGESTORE

PERCEPTUALPROCESSOR

COGNITIVEPROCESSOR

MOTORPROCESSOR

Memory 1 - Perceptual Buffersto briefly store impressions

Memory 2 - working memory,small capacity, conscious

thought, calculations

Memory 3 - permanent memory, hugh capacity


Block Diagram – MHP – Three Memories, Rep’n, Decay Time, Size

LONG-TERM MEMORY


AUDITORY IMAGESTORE

VISUAL IMAGESTORE

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 (1 chunk) = 73 [73-226] sD (3 chunks) = 7 [5-34] sS = 7 [5-9] chunks

R = RepresentationD = Decay TimeS = SizeC = Cycle Time [Range]

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

R = Semantic + Visual + AuditoryD = Infinite S = Infinite


Memory 1 – Perceptual Stores (sensory memory)

• Memory structures Image Stores - Holds fixed image of

outside world long enough for some analysis

• Processes - Info goes to brain for more processing e.g. Pattern recognition Uses context & knowledge to make sense

of what is seen/heard


Perceptual Stores

• Visual and auditory impressions Visuospatial sketchpad, phonological loop

• Very brief, but accurate representation of what was perceived Details decay quickly (70 - 1000 ms

visual; 0.9 - 3.5 sec auditory) Limited capacity (7 - 17 letters visual; 4 -

6 auditory)


Perceptual stores

• buffers for incoming data via senses• different one for each sense• short-lived and space-constrained• persistence (fireworks in vision after the

fact)• some processing even if not attended• attention brings it into STM

cocktail party phenomenae


Memory 2 – Short Term Memory STM

• Representation is either auditory or visual• Rehearsal needed to prevent decay (try

it) Without rehearsal, decays in minute or less Can store as long as are able to pay attention

to rehearsal – harder than you think (try it)– Another task prevents rehearsal - interference– New info can “push out” old info - interference

• Capacity is 5 to 9 “chunks” of information


About Chunks

• A chunk is a meaningful grouping of information – allows assistance from LTM

• 4793619049 vs. 404 894 7328• NSAFBICIANASA vs. NSA FBI CIA

NASA• My chunk may not be your chunk

User and task dependent


STM

• gateway to sensory and LTM? no – conversation goes directly to LTM

• role of rehearsal exaggerated (moving from STM to LTM) lots in LTM that is not rehearsed (eg.

snapshot of a birthday celebration)


STM characteristics

• recency - last few items in list recalled better than middle - holding most recent items in STM negate with interference? visual and auditory channel - no

interference if different channel

• primacy - first few items in list recalled better than middle (more rehearsal)


STM characteristics

• quick access and quick decay (volatile)• limited in size

chunking (experts vs. novices) - phone number– 402-111-5555

• forgetting time decay? interference with new items? (eg. similarity) attention moves off item?


Memory 3 – Long-Term Memory LTM

• Seemingly permanent & unlimited• Slow but variable access speed• Access is harder, slower

-> Activity helps (we have a cache)

• Representations are semantic (declarative, procedural) and visual and auditory Facts, procedures, pictures, sounds

• Retrieval depends on network of semantic associations (“linked lists”)

File system full


LTM characteristics

• Retrieval depends on …. recency expectations similarity of information connectedness rehearsal richness & nature of processing at learning

– level or depth or processing (shallow vs deep perceptual analysis)

– distinctiveness of processing– amount of processing

• elaborate far better


Richness

• paragraph – listen and remember …..


Types of LTM

• Explicit and Implicit conscious recollection, top-down

retrieval from multiple systems with massive integration (E)

unconscious recollection, bottom-up from single system (I) – more automatic


Types of LTM

• Episodic and Semantic episodic: self-awareness component,

things that happen to you, complex (E) semantic: stuff we know, knowledge

about the world, relationships, implicit - dictionary, thesaurus

• likely stored the same way


Types of LTM

• Declarative and Procedural knowing that, explicit primarily,

relationships, integration of information (D) – knowing things and their relationships

knowing how, mostly implicit, not relational – how to do things


Memory structures for stories, events …

• Schema - framework that includes frames & scripts become chunks for expanding memory basis for expectations

• Bartlett’s Schema Theory framework for stories that affects comprehension told American Indian stories, then recall -

– readjusted story elements and themes to fit their model

• Chunking in experts• Helps make it easier to recall, group information• Experts have great, robust schema and chunks


LTM processes

• Storage rehearsal

• Retrieval Forgetting Recognition vs recall Frequency and recency effects


Storage- Rehearsal

• Memorization involves storing the information and one or more access paths

• Good memories are rich semantic networks with many (unique) access paths

• Learning is aided by meaningfulness, structure, familiarity and concreteness

• Active memorizing requires effort, motivation• Passive memorizing - unpredictable, often episodic,

context sensitive• Similar items interfere if they are not separated during

memorizing - learning transfer effects - old interfere with new; new overwrite old


Facilitating Memorization

• Structure information to help chunking - use categories, ordering, associations

• Encourage reasoning during memorizing - active memory

• Help access by multiple pathways - memorizing tricks e.g. keywords, cognitive aids, mnemonics, link to image memory (rooms)

• Make associations clear and keep them consistent


Facilitating Memorization

• Make separate and recognizable contexts for recall - important for script / skill memory

• Increase depth of encoding Richness Visualization

– sorting - http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html

Uniqueness Interaction

• Recognition vs Recall

http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html

http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html


Facilitating Memorization: Mnemonics

• cognitive mnemonics ABC’s with tune on old olympus mountain tops a finn

and german viewed some hops (12 crainial nerves: OOOMTAFAGVSH)

– seems to be more to remember?


Facilitating Memorization: Mnemonics

• check out: http://human-

factors.arc.nasa.gov/cognition/tutorials/index.html

• mnemonic for Norman principles: visibility, feedback, cognitive/conceptual model, affordance, mapping

My Fat Cat Ate Veggies

http://human-factors.arc.nasa.gov/cognition/tutorials/index.html




Recall vs. recognition• Knowledge in the World Theory is GUI’s - Alan

Kay developed in 1960’s Steve Jobs in late 1970’s from Xerox Parc keep knowledge in world to supplement head

knowledge recall vs. recognition remember just enough detail to get by

– exceptions rather then norms experts not expert in knowledge in the head as

much as expert in how to locate needed knowledge in the world (Norman Ch 2)


Design implications

• Reduce cognitive load!!!


Design implications

• Mental models natural extensions of schema - support schemas metaphors - desktop/office match system information structure

with familiar memory structures so user can use their schema


Design implications

• Design interfaces that help users ‘grow’ good mental models meaningful and familiar command names (eg. from

task world) balance this with existing conceptual models of

item names (ie. cut, copy)• Incorporate closure (finish) on tasks

helps build mental model helps identify chunks for memory when become an

expert

• Consistency - to build mental model; don’t have to remember as much


Design implications

• Rich encoding - multimedia interaction context?

• May just be to ‘remember your site’ or help with visualization http://www.jordans.com/roomplanner.asp http://www.smartmoney.com/marketmap/ http://www.sitepal.com/?source=gawweb06&kw

=talking+website&creative=581895729

http://www.jordans.com/roomplanner.asp

http://www.smartmoney.com/marketmap/

http://www.sitepal.com/?source=gawweb06&kw=talking+website&creative=581895729

http://www.sitepal.com/?source=gawweb06&kw=talking+website&creative=581895729


Design implications

• Focus on recognition rather than recall interface contains prompts/information studies on computer experts found

they don’t have better recall, but high recognition of what is and isn’t available on interface and where to find it (mental maps)

GUI’s combination of recognition (menu’s) and recall (quick keys)


Design implications

• Place the burden of remembering on the machine, not the human Don’t require user memory (eg.

between screens) Don’t have computer ask for info it

can derive


Design implications

• Design minor messages, alerts, warning to be minimally disruptive prevent user from forgetting data

stored in short term memory


Attention

• Humans can focus mental resources on a single event/object helps to simplify environmental input (filter) works with perception - perceive what

attending to can divide attention (multiprocessing, not

parallel)– problem - distraction on second task, don’t return to

first task in right place.• often use world reminders to hold place in first task (post-it

note)


Attention

• examples driving a car -must attend to some

stimuli, ignore others listening to this lecture - attend to

slides and words, ignore other students, physical plant noises


Divided attention

• doing two things at once• affected by

task similarity – similar how? practice (experience) -

automaticity task difficulty – require more

resources than are available?

• what happens: interference


Success in time sharing attention

• four mechanisms account for how well we divide our attention 1. automaticity and resources 2. resource allocation and switching 3. structural factors 4. confusion and similarity


1. automaticity and resources

• Automatic vs. Controlled : perform task without thinking about it or require attention, conscious control. Happens over time. Controlled – do something directed by thought.

• Automatic: good as fast, doesn’t interfere with other tasks (need

minimal attention), unconscious bad - unavailable to conscious level, hard to change

(driving a shift), can interfere with other automatic processes, harder to unlearn

www.apa.org/science/stroop.html)

http://www.apa.org/science/stroop.html


automaticity

• Stroup effect – read the words on next page outloud as fast as you can …


Mismatch

• Stroop effect: name the colour:REDGREENBLUEYELLOWBROWNPURPLE

• Color has not been shown empirically to be superior


1. automaticity and resources• automatic processing can time-share

efficiently doesn't require a lot of cognitive resources

– eg. walking

factor: effort and difficulty of additional tasks

• if task difficult, requires more resources if have dual tasks, performance will decrease

since resources are being shared automatic tends to reduce the difficulty


1. automaticity and resources

• can only increase performance so much level equal to ‘full’ resource use on a

task, performance data limited (no further benefit from adding more resources)– perfect example: no matter how hard I try

(invest resources & effort), I won't improve my understanding of a discussion in French beyond a rudimentary level.

– also called resource-limited


1. automaticity and resources• bottom line

increase effort into a task, improve performance to point if resource limited

increase difficulty of task decreases performance unless add resources

in dual tasks, if increase resources for one task, will decrease resources for second task and subsequent performance– depends on automaticity


2. resource allocation and switching

• result of two + tasks co-occuring• now look at how you can allocate and

switch attention between tasks we don't have elaborate schemes to

optimize resource allocation– can improve time sharing with these

strategies– totally depends on the individual

• can train how to control attention


2. resource allocation and switching

• factors switch cost (so tend to stay with same

task even if low priority) cognitive distance of tasks - if close,

more confusion when switch (so more costly)

faster switch if salient reminders available about task (eg. you can see it vs. just remembering)


3. structural factors

• perceptual resources required, brain structures used, info processing required

• Bottleneck Theory- use same resources, get a bottleneck that shared tasks must wait for

• bottom line amt. of interference between two tasks depend

on degree to which each requires same resources (shared levels on these three dimensions)


4. confusion and similarity

• confusion: increasing the similarity of processing material decreases efficiency (too similar) eg. mental math and spelling, Stroup effect

– semantic value of word interferes with ability to report ink color

• what happens: responses for one task activated and interfere with second task


Visual attention theories

• how attention works overall gestalt (salient features), focus

down on objects and components affected by experience (bananas

yellow)


Designing for attention

• examine which configurations minimize task interference voice recognition software - may

interfere if user has to perform other verbal activities– best with spatial activities

• avoid imposing two tasks using similar materials (confusion)

– entering digits while others speaking digits



• what about background music? requires spatial perception decreased performance with lyrics and

word processing

• examine mental workload • urgent info in prominent area; less

urgent to specific area(s)



• Ways to focus user attention structure information

– group like things • physically, with fonts, with color, spacing, lines, etc.

– use same spot for same types of information

to help with distractions: system should inform you where you were in task when left

– let user know position in state space avoid unnecessary information display (KISS) make things easy to use/move thru (so user not focused

on mechanics of how to use system)



• taking advantage of automatic processing: quick keys across systems standards (like Windows 95 ^c, ^v, ^x) become

automatic– problem - appears unrelated to task to most people

• avoid automaticity by interrupting process (eg. put a window up in middle of keystroke sequence)

– good for deleting


Learning

• Two types: Procedural – How to do something Declarative – Facts about something

• Involves Memorization Understanding concepts & rules Acquiring & automating motor skills

– Swimming, Bike riding, Typing, Writing. Tennis– Driving to work

• Even when don’t want to


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 - Reasoning from a fact to the action or state

that caused it


Goal in UI design - Facilitate Problem Solving!

• How can you help the user apply these three kinds of reasoning while learning/using a UI? …..

Deductive

Inductive

Abductive


Reasoning about a UI

• Deductive: If I want to delete something, I must first select it. Facilitate by animating the disappearance of selected object

• Inductive: I could make text bold by selecting it and then using the Bold command. Maybe I could italicize in the same way. Facilitate by putting bold and italic commands together

• Abductive: Timeout on the web browser if not connected. Facilitate by telling the user why the timeout occurred


Observations On Learning a UI

• 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 of Observations

• Allow flexible shortcuts Forcing plans will bore user

• Allow multiple ways of doing things Select-cut-paste Select-drag

• Provide active rather than passive help Recognize dead ends and inefficient

methods


Language

• Domain terminology - use• Technical terminology - avoid• We read word shapes, not letters

Unless all caps

• Should systems have natural language interfaces? Stay tuned


People

• Good1. xxx2. yyy3. zzz

• Bad1. aaa2. bbb3. 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


Evaluate these

• http://happydeluxe.com/• http://www.google.com vs

http://www.yahoo.com• http://www.northcantonmedical.org/• http://www.enchantedharp.com/• http://www2.creighton.edu/business

Analytics can identify key areas

http://happydeluxe.com/

http://www.google.com/

http://www.yahoo.com/

http://www.northcantonmedical.org/



http://www.enchantedharp.com/

http://www2.creighton.edu/business

ITM 734 Introduction to Human Factors in Information Systems Cindy Corritore [email protected] This...

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