HCI Frameworks How we conceptualize users of computing systems

Human Role How is human viewed in HCI – What is human role? Different roles engender different frameworks 2

Human Roles Human considered to be a… 1. Sensory processor – Experimental psych, sensory psych e.g. Model-Human Processor (Card, Moran & Newell) 2. Interpreter/Predictor – Cognitive psych, AI e.g. Distributed cognition (Hutchins) 3. Actor in environment – Activity theory, ethnography, ecol psych e.g. Situated action (Suchman) e.g. Activity theory (Vygotsky, Nardi) 3

What Makes a System Usable 4 Human considered to be a… Usability results when the system… Sensory processor Fits within human limits Interpreter/Predictor Fits with knowledge Actor in environment Fits with task and social context

Evaluation Methods 5 Human considered to be a… Evaluation methods… Sensory processor Quantitative experiments Interpreter/Predictor Task analysis, cognitive walkthrough Actor in environment Ethnographic field work, participatory design

Two Views of Interaction Interaction with – Software system is a tool or machine – Interface is a usability-engineered membrane – Human-as-processor & -interpreter models Interaction through – Software is a medium used to interact with task objects or other people – Interface plays a role in social context – Human-as-interpreter & -actor models 6

What are Humans Really Like? Models of behavior are only part of the information we need for successful design Need to know how users really are Abilities, needs, preferences 7

Human Abilities 1 Understanding the user

Typical Person 9

Human Capabilities Why do we care? (better design!) Want to improve user performance Knowing the user informs the design 1.Senses 2.Information processing systems 3.Physical responding 10 Time and effort expended to complete tasks

Overview 11 I. Senses A. Vision B. Hearing C. Touch D. Smell? III. Motor systemII. 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 C. Motor system TODAY’S CLASS NEXT CLASS

I. Senses Sight, hearing, touch important for current HCI – smell, taste ??? Abilities and limitations affect design 12

Vision Visual System – Eye – Retina – Neural pathway ~ 80% of brain’s operation 13

Visual Abilities Sensitivity – luminance: ~10 7 mL (see notes) Acuity – detection, alignment, recognition (visual angle) – retinal position: fovea has best acuity Movement – tracking, reading, vibrations Note: Vision decreases with age Implications (??) – Font size & location depends on task – Much done by context & grouping 14

Color Vision Color & the retina – 380 (blue) ~ 770nm (red) – Problems with cones or ganglion cells causes problems with color perception – (not really “color blindness”) – 8% males, 0.5% females Implications (??) – avoid saturated colors – color coding should be redundant when possible 15

Perception Matters in Usability Read-flow principle: – Action items (buttons, links) should support the flow of the user in the same way as reading occurs. – The last action should be the most-likely action to avoid backtracking. – Left=back, stop, quit, cancel, previous – Right=next, continue, submit 16 Next Slide >><< Previous Slide

Read flow… FLOWS DOES NOT FLOW

Hearing Capabilities (best-case scenario) – pitch - frequency ( ,000 Hz) – loudness - amplitude ( dB) – location (5° source & stream separation) – timbre - type of sound (lots of instruments) Implications (??) 18

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 19

Overview 20 I. Senses A. Vision B. Hearing C. Touch D. Smell? III. Motor systemII. 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 C. Motor system

III. Motor System Capabilities – Range of movement, reach, speed, strength, dexterity, accuracy Often cause of errors – Wrong button – Double-click vs. single click Principles – Feedback is important – Minimize eye movement 21

Project (P1) Part 1 - Understanding the problem – Discovery process – In UCD terms, determine Context/Domain, Users, Tasks, and their design implications – Who is it, what do they need to do, and where? – Interpretive evaluation of current interface, if it exists – Establish objectives, requirements for (re)design Feel free to use Wiki space for sharing, coordination 22

Reminder: UCD 9 Steps 23 1.Define the Context 2.Describe the User 3.Task Analysis 4.Function Allocation 5.System Layout / Basic Design 6.Mockups & Prototypes 7.Usability Testing 8.Iterative Test & Redesign 9.Updates & Maintenance PROJECT PART 1

1. Define the Context 24 Context: the “type” of uses, applications – Life critical systems, applications – Industrial, commercial, military, scientific, consumer – Office, home, entertainment – Exploratory, creative, cooperative Market Customer (not the same as the User) …Design Impacts?…

2. Describe the User (!!) 25 Physical attributes (age, gender, size, reach, visual angles, etc…) Physical work places (table height, sound levels, lighting, software version…) Perceptual abilities (hearing, vision, heat sensitivity…) Cognitive abilities (memory span, reading level, musical training, math…) Personality and social traits (likes, dislikes, preferences, patience…) Cultural and international diversity (languages, dialog box flow, symbols…) Special populations, (dis)abilities Design Implications?!

3. Task Analysis 26 Talk to and observe users doing what they do; find out what they want/need to do Explore the PROBLEM SPACE List each and every TASK and component STEPS HABSTRACT into standard tasks

DELIVERABLES Writeup with your results in HARDCOPY form. Here is how you might structure your project: Title, team name, team members Project description – Give a description of the system you’re working toward and what you expect it will do. This will still be fairly high-level at this point. Context – Describe the context in which you expect your application to be used. This isn’t just where it will be used, but also the implications of that context. – Who would be the customers for your application (may be the same as the users, but may not be)? What impact does the customer have on the context? – What are the design implications for an application that will be used in this context? Be specific. Users – List and define at least three types of stakeholders you’d expect to use your system. – Indicate what characteristics you expect to be relevant to these stakeholders – What are the implications for your design that arise from these characteristics? Task Analysis – Describe how you did your task analysis: what methods, what users, how did you do your data collection? – Formal task analysis for your system. Choose the representations you’ll use (e.g., Task Outlines, Narratives, Hierarchies and Network Diagrams, Flow Charts). Present your task analysis, as well as a justification for the chosen representations 27

Upcoming More on human abilities (cognition) Task Analysis Requirements Definition Evaluation without users – Heuristic evaluation – Ethnography 28