CS1512 Part 4: Introductory Notes on Human Factors

1
CS1512Part 4 Introductory Notes on Human
Factors Human Computer Interaction (HCI)

• Kees van Deemter
• University of Aberdeen
• (Much of the following is based on
  transparencies by L.Ciolfi and M.Cooke,
  Interaction Design Centre, University of
  Limerick)

2
Introductory Notes on Human Factors Human
Computer Interaction (HCI)

• Early history
• An influential figure Donald Norman
• A crucial issue evaluation

3
Short history re. ergonomics, human factors (1)

• Ergonomics - Ergos (greek) - work.Nomos
  -study, science
• Fitting the human operator to the machine
• Early focus on manual work, design of tools
• Frederick W. Taylor (1900s) Engineering work
  rates
• Time and motion studies, automation
• Frank B. Gilbreth study of motion
• E.g., bricklaying, 1911
• 2nd World War - growth of human factors
• selection of pilots etc., training, assessment,
  design of controls, ...
• Heavy Military involvement to this day.
• But, Not everyone is a 29-year old airforce
  pilot

4
Short history re. ergonomics, human factors (2)

• Development of man-machine communication in
  1960s
• Work of US human factors researchers (e.g.
  Alphonse Chapanis)
• Fitts Lists (1951)
• Machine is better at / Man is better at
• (MABA-MABA list)

5
Short history re. ergonomics, human factors (3)

• People are better at
• detecting small amounts of visual, auditory,
  chemical energy
• Perceiving patterns of light or sound
• Improvising
• Storing information for long periods of time, and
  recalling appropriate parts
• Reasoning inductively
• Exercising judgement

6
Short history re. ergonomics, human factors (4)
MABA-MABA list

• Machines are better at
• Responding quickly to control signals
• Applying great force smoothly and precisely
• Storing information briefly, erasing it
  completely
• Reasoning deductively

7
Short history re. ergonomics, human factors (5)

• Work on public safety and health design
  standards, regulations re. equipment safety
• Focus on fitting machine to human
• Shift from machines to computer interfaces
• Shift from machine operators to everyday users
• Origins of HCI as distinct field
• Interest in human use of computers, writing and
  understanding programs
• 1982 - First HCI conference
• 1983 -gt ACM CHI conferences

8
2. The Design of Everyday ThingsDonald A. Norman
9
The psychopathology of everyday things

• Door handles
• Light switches
• Taps
• Telephones
• Microwaves
• VCRs

10
Affordances

• the perceived and actual properties of the
  thing, primarily those fundamental properties
  that determine just how the thing could possibly
  be used

11
Affordances

• Plates are for pushing
• Knobs are for turning
• Buttons are for pressing
• No picture, label or instruction is required

12
Doors are for opening
13
Once at Philips (1993-1994)

• New high-end audio set was designed specifically
  for elderly customers
• CD, Cassette player radio, all in one. Number
  of buttons was minimised by function sharing.
  E.g., Fast Forward button
• CD fast foward through CD
• Cassette player fast foward through cassette
• Radio ...

14
Once at Philips (1993-1994)

• New high-end audio set was designed specifically
  for elderly customers
• CD, Cassette player radio, all in one. Number
  of buttons was minimised by function sharing.
  E.g., Fast Forward button
• CD fast foward through CD
• Cassette player fast foward through cassette
• Radio search for next radio station

15
Once at Philips (1993-1994)

• Experiment show the set to naive subjects ,
  without any explanation. Then record their
  conversation.
• One finding Many people did not see that the set
  contained a radio
• Clearly something wrong with the affordances of
  the audio set!

16
Normans Action Cycle
17
Normans Seven Stages of Action
Goals
Execution
Evaluation
Evaluation of interpretations
Intention to act
Interpreting the perception
Sequence of actions
Execution of the action sequence
Perceiving the state of the world
The World
18
Norman highlighted two problems in particular

• The Gulf of Execution The difference between the
  intentions and the allowable actions
• The Gulf of Evaluation the amount of effort that
  the person must exert to interpret the physical
  state of the system and to determine how well the
  expectations and intentions have been met.

19
Principles of good design
20
Provide a good conceptual model

• A conceptual model allows the user to simulate
  the operation of the device.
• A good conceptual model allows the user to
  predict the effects of their actions.

21
(No Transcript)
22
Make things visible

• By looking, the user can tell the state of the
  device and the alternatives for action.
• It helps when the user can map what he sees now
  to something he has seen before. A mapping may
  rest on
• Physical analogies
• Cultural standards

23
Car speaker control (analogy between size and
amplitude)
24
Natural mapping
25
Good mappings ...

• ... make it possible to determine the
  relationships between
• Controls and their effects
• The system state and what is visible
• Actions and results

26
The Principle of Feedback

• Sending back information to the user on what has
  been done.
• The user should receive full and continuous
  feedback about results of actions.

27
From hardware to software

• All this is even harder in relation to software
• If you make a door, then chances are that
• you can see that it can be opened
• you can see how it may be opened
• you can hear when it closes
• If you make a web page, you have to explain
• what can be done with it
• how it can be done
• whether youve managed to do it

28
Small case study data projection in MT1
projector
video
PC
On
Off
laptop
pic mute
29
To switch on the projector (when laptop is to be
used)

• touch button marked projector
• touch button marked on
• wait about 20 seconds until projector starts
  casting some light
• Can you detect any problems?

30
Problems with this interface

• Why is it not sufficient to touch
  projector?(What else could you do with it then
  switch it on or off??)
• Layout suggests that on/off apply to the box
  to their left, not to the projector. (No natural
  mapping)
• Lack of early feedback suggests that you have
  failed to switch the projector on (even if, in
  fact, you have).
• BTW textual explanation is provided, but not a
  word on all this

31
Conclusion from Normans work

• Things dont have to be so hard to use.
• Even the best-trained and best-motivated
  designers can go wrong when they listen to their
  instincts instead of testing their ideas on
  users.
• Evaluation is crucial

32
3.How to evaluate
33
Usability Issues

• Inappropriate decision criteria for interfaces
• I like it ...I always do it that way...Its
  conceptually appealing to me
• Evaluation of systems often too little, too
  late.
• It is important to build in evaluation right
  through systems development, from needs
  assessment through to interface design and field
  testing.

34
Usability Issues

• 1. Early Focus on Users Tasks
• designers must understand who the users will be
  -study users and tasks (work)
• 2. Empirical Measurement
• users should try out prototypes to do real work -
  record, analyse their performance
• 3. Iterative Design
• must be a cycle of design, test, measure ( and
  repeat..)
• principles seem intuitive, but many designers
  still do not recommend or follow them...

35
Usability ... Empirical Measurement

• User diversity is often underestimated. (Think of
  differences in experience, age, disabilities.)
• E.g., People who have developed a system think
  differently about its use, do not make the same
  mistakes, and use it differently from novices...
• Testing on yourself is better than nothing, but
  no substitute for actual users...
• Simply asking users is not the answer..need
  scenarios, mockups prototypes so users can
  experience future use situation

36
Competing ideas/approaches

• Belief that Design Guidelines are sufficient
• too general as constraints on design ..ignores
  contextual factors..
• guidelines as informal collections of
  suggestions, not distilled science...
• Analytic approaches the holy grail of HCI is an
  analytical model that predicts usability. But
  this goal is still very far away. Current
  analytical models leaves things out..too much
  armchair reflection...mismatches with existing
  systems in settings