Spring 2002

1

Chp.1: What is HCI?

• study of interaction between humans & computer• a methodology for:

– modeling the human (e.g., perception, behavior)– examining usability of computer programs,

devices, techniques (in general doesn’t have to be just computers, applies to anything man-made that humans use, e.g., cars, light switches, kettles, etc.)

• most imporantly: HCI leads to DESIGN of interface• past contributions: physical devices (mouse, HMD),

code (GUI toolkits, window managers)

Spring 2002

2

Chp.1: What is HCI?

• All about design - in the context of Computer Science, design of interface to “back-end” program

• Interface:– graphical (GUI)– command-line (CLI)– web-based– VR, etc.

• “Back-end”:– Operating System (O/S)– dB– web site– spreadsheet– calculator

– word processor– air traffic control display– flight simulator– nuclear plant– automobile displays– etc.

Spring 2002

3

Chp.1: What is HCI?

• Computer interaction– almost ubiquitous (everywhere); chances are in whatever

device you use, there’s a chip in there– e.g., typical day:

• get up, press “snooze” on alarm clock (what’s the interface on the clock?)

• drive to work (car interface)• stop by ATM (ATM screen)• after work, shopping (scanners at store)• at home, eat dinner (microwave, stove)• watch TV/DVD/VCR (various ent. devices)

• Interface design applies to all these; computer interface is more obvious in some than in other examples

Spring 2002

4

Chp.1: What is HCI?

• Why bother with interface design?– increasing productivity

• e.g., in the workforce: employees with a better word processor will be more productive

– safety: critical systems with poor interface may endanger lives• e.g., ATC, operating room, nuclear plant

– commerce: a good interface may sell a product• e.g., today’s “hot items”: MP3 players, digital cameras,

DVD players, etc.• Key point: users shouldn’t have to think (much) about

intricacies of interface to use the tool (INTUITIVE INTERFACE)– e.g., ATM: walk up to it, withdraw cash (fairly easy to use)

Spring 2002

5

Chp.1: What is HCI?

• Key principles of interface design:– visibility: controls should be visible (e.g., volume

control on an MP3 player)– affordance: controls should map to their function,

I.e., it should be obvious what each control (button, slider, etc.) does.• controls should be intuitive, e.g., volume

control: use a vertical slider (up = loud)– feedback: device should give user indication of its

state (e.g., phone: dial tone [ready], busy signal, flashing light [message or on hold])

Spring 2002

6

Chp.1: What is HCI?

• Examples of design, visibility, affordance, feedback

Fig.1: salt / pepper shakers: which is which?

Spring 2002

7

Chp.1: What is HCI?

• Examples of design, visibility, affordance, feedback

Fig.2: which knob controls which burner?

Spring 2002

8

Chp.1: What is HCI?

• Examples of design, visibility, affordance, feedback

Fig.3: can I set the freezer / fridge temperature independently?

Spring 2002

9

Chp.1: What is HCI?

• When designing a computer program:– think what capabilities program should have– how is a user going to access those functions

• More formally,– HCI is a discipline concerned with the design,

evaluation, and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them

• NOT just the creation of “user-friendly” programs• Need to understand human processes (cognition,

perception) and interaction protocol between human and computer

Spring 2002

10

Chp.1: What is HCI?

• HCI challenges:– continuous technological development, e.g.:

• better / faster machines• new languages, applications (web, internet,

VR, multimedia, imaging, graphics, etc.)– two concerns:

• keep abrest of technology (e.g., SIGCHI)• marry good HCI with effective use of

technology (I.e., make sure both are good: the “back-end” program works and the interface is good)

Spring 2002

11

Chp.1: What is HCI?

• HCI Goals:– production of usable, safe, and functional systems– development or improvement of systems (including

computing systems), with respect to:• safety• utility (functionality, what system does)• effectiveness (is it good at what it does)• efficiency (in case of programming, speed, memory

utlization, etc.)• usability (key concept in HCI: make system easy to learn

and use)– system: consider complete environment, not just hardware

or software, but people

Spring 2002

12

Chp.1: What is HCI?

• Examples of not very usable systems:– complicated telephones

• do you use all the features (e.g., multi-party conf. calls, call forwarding, call-waiting, etc.)?

– wristwatch• how often do you use its “extended” features

(time zone, stopwatch, alarm, countdown timer, etc.)

• Examples of very usable systems:– scissors

• intuitive how to use, mainly because it mostly has just one application

Spring 2002

13

Chp.1: What is HCI?

• Underlying HCI belief: people come first; a computer is just a tool, a means to accomplish some task, e.g.,– writing a paper– communicating with friends– designing a landscape– preparing income taxes– cataloging, organizaing, printing pictures– desinging roads, bridges, airplanes, cars, etc.

• For good design, need knowledge of humans and technology– often need multi-disciplinary teams (e.g., Comp.

Sci, Psychology, IE, Arts, etc.)

Spring 2002

14

Chp.1: What is HCI?

• Evolution of HCI– 70s--80s: psychologists interested in information-

processing aspects of computer as analogy to mental processes (e.g., modeling brain as a computer, connectionist network, associative memory, etc.)• various HCI studies: testing menus (depth vs.

breadth), usability of single-user computer– 80s--90s: examining more powerful PCs,

workstations, communication (e.g. email), multimedia (e.g., imaging, visualization, “data mining”), VR (“presence”), group work (CSCW)

Spring 2002

15

Chp.1: What is HCI?Evolution of HCI: three landmark systems

1. Dynabook• Alan Kay, Xerox Parc• one of first laptops (book-sized PC)

2. Star• Xerox Parc• desk-sized system• high-res display, graphics, icons• mouse mapped to 2D “desktop” on screen

3. Apple Lisa• based to some extent on Dynabook & Star• precursor to Macintosh• WIMP: Windows, Icons, Menus, Pointer• introduction of desktop metaphor• GUI, WYSIWYG word processor

Spring 2002

16

Chp.1: What is HCI?Evolution of HCI: Main considerations

• All HCI takes place in social & organizational context• Application design is geared towards specific purposes,

dividing tasks between human and machine• To adapt application to human, need to know something about

human psychological and physiological abilities and limitations– human info processing: limited attention, memory– language: linguistics, verbal comm.– communication: methods of, body language, emoticons,

etc.– interaction: human-to-human, e.g., turn-taking– ergonomics: carple-tunnel syndrome, eye strain, fatigue, …

Spring 2002

17

Chp.1: What is HCI?Evolution of HCI: Main considerations

• To create successful computer application, need to know something about capabilities and limitations of computer– input: devices, e.g., keyboard, mouse, camera,

microphone, sensors, etc.– output: displays, graphics, sound, etc.– dialogue techniques, genre, style: what & how to

communicate to user, e.g., state of system, output (visualizations, charts, numbers, etc.), what colors to use, animation speed, etc…

Spring 2002

18

Chp.1: What is HCI?Discussion

• Can you think of examples of:– very usable systems– not so usable systems (are there any devices that

appear to be confusing to people)? How can they be improved?

• Can you think of examples of:– very usable computer programs– not so usable computer applications? How can

they be improved?• ASSIGNMENT 1: collect at least 3 examples

(pictures) of not so usable “systems”, e.g., door, whatever, doesn’t have to be computer program

Spring 2002

19

Chp1: Goals of System Engineering

• Functionality• Reliability, availability, security, data integrity• Standardization

– common UI features (e.g., WIMP)• Integration

– of multiple components/modules (libs)• Consistency

– common action sequences (e.g., File->Open)• Portability

– e.g., Mac OS X, Linux, Windows

Spring 2002

20

Chp.1: Goals of UI Design

• Human factors central to evaluation:– Learnability (time to learn)– Performance– Human error (rate of errors by users)– Retention (easy to use?)– Satisfaction (subjective)

Spring 2002

21

Chp.1: Human Modeling

• Human cognitive and perceptual abilities– Short-term memory– Long-term memory and learning– Decision making– Attention and set (scope of concern)– Search and scanning– Time perception

• Personality differences• Cultural diversity• Universal accesibilty (users with disabilities)• Elderly users