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 RolesHuman 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 consideredHuman considered

to be a…to be a…Usability results Usability results when the system…when the system…

Sensory processorSensory processor Fits within human Fits within human limitslimits

Interpreter/PredictorInterpreter/Predictor Fits with knowledge Fits with knowledge

Actor in environmentActor in environment Fits with task and Fits with task and social contextsocial context

Evaluation Methods

5

Human consideredHuman considered

to be a…to be a…Evaluation Evaluation methods…methods…

Sensory processorSensory processor Quantitative Quantitative

experimentsexperiments

Interpreter/PredictorInterpreter/Predictor Task analysis, cognitive Task analysis, cognitive walkthroughwalkthrough

Actor in environmentActor in environment Ethnographic field work, Ethnographic field work, participatory designparticipatory 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 design1. Senses2. Information processing systems3. Physical responding

10

Time and effort expendedto 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’SCLASS

NEXTCLASS

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: 10-6~107 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…

FLOWSDOES NOT FLOW

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)

• 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 Context2. Describe the User3. Task Analysis4. Function Allocation5. System Layout / Basic Design6. Mockups & Prototypes7. Usability Testing8. Iterative Test & Redesign9. 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)abilitiesDesign Im

plicatio

ns?!

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

ABSTRACT 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