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 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? From

Audition (Hearing) Capabilities (best-case scenario) – pitch - frequency ( ,000 Hz) – loudness - amplitude ( dB) – 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

Activity: Find the price of a double room at the Holiday Inn in Bradley From

Activity: Find the price for a double room at the Quality Inn in Columbia From

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

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

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 IMAGE STORE VISUAL IMAGE STORE R = Semantic D = Infinite S = Infinite R = Acoustic D = 1.5 [ ] s S = 5 [ ] letters R = Visual D = 200 [ ] ms S = 17 [7-17] letters R= Acoustic or Visual D (one chunk) = 73 [73-226] s D (3 chunks) = 7 [5-34] s S = 7 [5-9] chunks R = Representation D = Decay Time S = Size C = Cycle Time PERCEPTUAL PROCESSOR C = 100 [5-200] ms COGNITIVE PROCESSOR C = 70 [27-170] ms MOTOR PROCESSOR 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: 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 – “chunks” of information Slower decay – sec – rehearsal prevents decay Another task prevents rehearsal - interference

About Chunks A chunk is a meaningful grouping of information – allows assistance from LTM vs 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 numbers From

Implications? Which is an implication of ? – 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

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 s - 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

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

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

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 Good 1. xxx 2. yyy 3. zzz Bad 1. 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!