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

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.

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 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

Color Surround Effect

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)

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

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) 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

Next Assignment: HTA

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!