1. Don Norman’s P.O.E.T. CS 4163 Citation: Donald A. Norman
The Psychology of Everyday Things
© 1988 by Donald A. Norman
Published by Basic Books
LCC: TS171.4.N
ISBN:
Additional materials:
Affordance, Conventions, and Design
by Donald A, Norman
in interactions (may + june 1999, pp. 38 – 42)
(available under ACM copyright)
Handouts: copies of pages 16, (Fig. 1.10) 47 (Figs. 2.2–2.5), 52–53,188–189)
Index of especially interesting passages (filename POET_index.txt)
Figures from User Centered System Design: New Perspectives on Human-Computer Interaction edited by Norman and Draper (filename Norman’s models (figures).pdf)
Saul Greenberg’s lecture slides <URL: (last checked on 14 May 2001)
CS 4163

2. Everyday Things Have a User Interface
Ken Olsen, (founder and CEO of Digital Equipment), confessed that he couldn’t figure out how to heat coffee in the company’s microwave
P.O.E.T. is
Psychology Of Everyday Things
Book by Don Norman
Contains
examples of poorly designed everyday objects
discussion of design processes
Also available in softcover as The Design of Everyday Things

3. Some Everyday Examples:
Figure 1.1 (coffee pot)
‘If I were placed in the cockpit of a modern day jet airliner my inability to perform gracefully and smoothly would neither surprise nor bother me. But I shouldn't have trouble with doors and switches, taps and cookers.’ (Norman, p. 2)
Coffeepot overhead: Figure 1.1 of POET (p.2)
‘Carelman’s Coffeepot for Masochists’
differentiate between the functional interface and the purpose
what it does vs. how a person attaches to it
it does brew coffee
but is it functional?

4. Another Example (1 of 4)
‘A friend’ told Don N. of the time ‘he’ got trapped in the doorway of a post office.
The entrance was an imposing row of perhaps six glass swinging doors, followed immediately by a second, identical row.
(That's a standard design — it helps reduce the airflow and maintain the indoor temperature of the building).
show slide of doors from Norman
Figure 1.2 (p.4) ‘A Row of Swinging Glass Doors in a Boston Hotel’

5. Another Example (2 of 4)
He pushed on the side of one of the leftmost pair of outer doors. It swung inward and he entered the building.
Then, before he could get to the next row of doors, he was distracted and turned around for an instant. He didn't realize it at the time, but he had moved slightly to the right.

6. Another Example (3 of 4)
So when he came to the next door and pushed it nothing happened. ‘Hmmm’, he thought, ‘must be locked.’ So he pushed the side of the adjacent door. Nothing. Puzzled he decided to go outside again. He turned around and pushed the door. Nothing. He tried the adjacent door. Nothing.
The door he had just come in through no longer worked. He turned around once more and tried the inside doors again. Nothing. Concern turned into mild panic. ... He was trapped!

7. Another Example (4 of 4)
Just then a group of people on the other side of the entrance way (far to the right) passed easily through both sets of doors.
He hurried over and followed them through.

8. Another Example (Conclusion)
How could such a thing happen?
A swinging door has two sides. One is pillar and hinge, the other moves. To open the door one must push the moveable side.
Pushing on the hinges has no effect.
In this case, the design had aimed for beauty, not utility. No distracting lines, no visible pillars, no visible hinges.
So how could one tell which side to push?

9. More Examples Computer disks Ergonomically correct chairs:
Old style floppies can go in any way
Small floppy goes in only one way
Why?
They are not really square
They are slightly rectangular
Ergonomically correct chairs:
Can anyone adjust them?
Old style floppies: 8" and 5¼"

10. How Are We Able to Use Everyday Objects?
Subtle clues
In public buildings do doors swing in or out?
We learn that about doors by experience
If there is no handle then we ‘know’ to push
Location of hinges, door knob, push bar give clues about how to operate the door
Point to mental model figure (Norman & Draper handout)
Also show Norman figure1.5 (p. 10) ‘Affordances of doors’
Note that part of experience is ‘cultural constraint’

11. Conclusions From These Examples:
Everyday devices have an interface, or boundary between device and user, which can be good, okay or terrible.
Principles that assist in design of usable everyday objects are useful to consider when designing software interfaces.
Heightened awareness of good vs. poor design of everyday devices can make us better evaluators of software interfaces.

12. P.O.E.T. Part II
What lessons about computer interfaces can we learn from everyday objects?
We'll begin with some properties of interfaces and some terms for them.
Then we'll examine reasoning about interfaces and objects.

13. P.O.E.T. Part II Related Readings In Preece et al.
Section 13.7 (pp. 273 – 282)

14. Affordances & Conventions
The affordances of an object are how it can be used, e.g. a chair affords support
It can be used for other things too, but it affords support
We know which properties are affordances from our cultural conventions

15. Perceived Affordances
Perceived affordances (PAs) are about perceptions of how an object in a simulated environment operates
E.g. a computer mouse ()
Affords grasping, pushing, pulling, clicking
A PA is that clicking while the mouse cursor is on an image on the screen does something particular

16. How Do We Learn Conventions?
If a part of an interface is intended to do something but it is not perceived as affording that then it is invisible — and useless
Clues are transmitted through
Clear, consistent fundamental design model
Appropriate mappings
Action/Feedback loop (visibility)

17. Visibility
The correct parts must be visible, and they must convey the correct message
Visibility must provide the appropriate information for achieving relevant tasks
If it is not visible to the user then the feature is not really present

18. Examples of Visibility
The holes in salt and pepper shakers help us identify which shaker is which
Norman used a slide projector on which the slides are changed with a single button, yet sometimes want to move the magazine backwards instead of forwards. To do so requires one to hold the button down for a longer press
This is invisible and makes for difficult use even when one knows how to do it and horrendous learning at first
(NB: many multifunction watches are similar)
Norman (p. 5) ‘The Leitz slide projector illustrated in figure 1.3 has shown up several times in my travels….’
Norman (p.110) anecdote about a multi-function watch in section entitled ‘Mode Errors’.

19. Too Much Visibility Can Be Bad
Don Norman visited a couple with a fancy washer-dryer with super-duper multi-symbol controls
All to do everything you ever wanted with cleaning clothes
One (an engineering psychologist) refused to go near it
The other (a physician) memorized one setting and tried to ignore the rest

20. Norman’s Too Much Visibility Example (cont.)
Someone went to a lot of trouble to create that design. The machine took account of everything about modern synthetic and natural fabrics.
The designers worked hard. They really cared.
But obviously they had never thought of trying it out or of watching someone try to use it!
If the design was so bad, if the controls were so unusable, why did the couple purchase it?
If people keep buying poorly designed products, manufacturers and designers will think they are doing the right thing and continue as usual.

21. An Important Property of Visibility
Visibility must be interpreted for the specific context in which users will be performing their tasks

22. Conceptual Models of Devices
Many clues for how things work come from users’ conceptual model of the device and interface.
Conceptual models — what interface tells you about how a system functions (what it does).
Your conceptual model of the bicycle (in Fig. 1.7) tells you that it will not work.
show slide 1.7
Figure 1.7 (POET, p. 13)
Carelman’s Tandem “Convergent Bicycle (Model for Fiancés)”

23. Conceptual Models of Devices
Part of our conceptual model is based on clues for how things work, from the visible structure of the device
Perceived Affordances
What one thinks they can do with some features
Constraints
Limits on what you can do
Mappings
Relationships of interface to action
Perceived Affordances
‘The term affordance refers to the perceived and actual properties of the thing, primarily those fundamental properties that determine just how the could possibly be used (see figures 1.5 and 1.6 [about doors]). A chair affords (“is for”) support and, therefore, affords sitting. A chair can also be carried...’ (Norman, p. 9, italics his)
‘Norman (1992, p.19) defines affordance as “a technical term that refers to the properties of objects — what sorts of operations and manipulations can be done to a particular object.”… Affordances play a large part in the design of objects but what is important is “perceived affordance” — what a person thinks can be done with the object. For example should a door be pushed open or pulled?’ (Preece et al., p. 6)
Human-Computer Interaction by Jenny Preece, Yvonne Rogers, Helen Sharp, David Benyon, Simon Holland, and Tom Carey, © 1994 The Open University, Published (1999) by Addison-Wesley
Quoting Norman’s Turn Signals are the Facial Expressions of Automobiles. Also published by A-W.
Mappings
‘If a design depends upon labels, it may be faulty. Labels are important and often necessary, but the appropriate use of natural mappings can minimize the need for them. Wherever labels seem necessary, consider another design’ (Norman, p.78)

24. Consider Scissors Holes are there to put something in
Holes afford grasping with fingers
Size of the holes are a constraint
Which and how many fingers
Mapping between holes and fingers
A set of possible operations is suggested and constrained by the holes

25. Example — Don Norman's Refrigerator
Don Norman's refrigerator has the controls that are shown in Fig. 1.8
Suppose
The freezer is too cold but
The fresh food is just right
How would you adjust the controls so that the freezer is warmer, and the fresh food stays the same?
show slide 1.8
Figure 1.8 (POET, p. 14)
My Refrigerator
description on pages 14 – 15

26. Don Norman’s ’Fridge (2)
Figure 1.9 shows two of the possible conceptual models of the refrigerator’s operation.
Which is right?
Show Figure 1.9 (P.O.E.T., p. 15)
Two Conceptual Models for My Refrigerator
Answer after click

27. Don Norman’s ’Fridge (2)
Figure 1.9 shows two of the possible conceptual models of the refrigerator’s operation.
Which is right?
It’s ‘B’.
The controls are not independent, even though they appear to be.

28. Example Mappings: Don Norman's Stove
How well/natural controls map to functions they control (including perceived affordances, and constraints)
show slides
Norman (p. 76 – 77, Figures 3.3 – 3.5)

29. Example Mappings
Consider the relationship between a set of controls and the results in a device
For example, with a steering wheel, turning it to the right makes tires turn right also
The mapping is the relationship between steering wheel interface and the action of the tires
Modal interface: turning right is right turn in Forward mode only.
Different in Reverse or Neutral modes.

30. Mappings — Conclusions
Mappings — relates interface to action
A device which leads to a good conceptual model is likely to be more usable than one that does not lead to such a model
When our conceptual model is incorrect, or inadequate, we may have problems using the device
The closer the mapping between the control and its function the more accurate the conceptual model
For everyday things, the conceptual models are not necessarily complex

31. Feedback
Sending back to the user information about what action has actually been done or what action has been accomplished

32. Feedback Examples Old style telephones provided
tactile feedback (‘feel’ when you pushed a button),
sonic feedback
tone sound when you pushed a button
sounds from the connection
Contemporary style phones
have more functions but often less feedback
may be more difficult to learn
may be harder to feel confident about using

33. Conclusions: Evaluation
Everyday devices have an interface or connection with users
Everyday devices can be designed well or poorly for the user and task
We cannot evaluate their design independently of either user or task
I recommend that you read pp. 188 – 202 of P.O.E.T. for a more in-depth summary of Norman’s Seven Principles for Transforming Difficult Tasks Into Simple Ones.

34. Conclusions: Evaluation
Dimensions to evaluate usability on
Visibility
Mappings
Feedback
Affordances
Design model
I recommend that you read pp. 188 – 202 of P.O.E.T. for a more in-depth summary of Norman’s Seven Principles for Transforming Difficult Tasks Into Simple Ones.

35. 7 Principles for Simplifying Difficult Tasks (1–3)
Use knowledge in the world and knowledge in the head
Simplify the structure of tasks
Make things visible: bridge the gulfs of execution and evaluation
Quoted from Chapter 7 of POET
(pp.189–191)
Knowledge in the world:
see diagram of mental models and interactions (p. 190 in POET, p. 152 in Preece et al.)
‘the world’ is the realm of the system
(pp.191–197)
Minimize the overhead of planning, etc. needed to carry out tasks
Keep the task the same, but provide mental aids
Use technology to give more visibility & feedback
Automate but keep much of the task the same
Change the nature of the task (e.g. remove manual nature of task)
Don’t take away control, user must feel in control
(pp.197–198)
See the gulfs figures (4163-gulfs.pdf)
Anecdote on p.198 about the remote control for a CD player

36. 7 Principles for Simplifying Difficult Tasks (4–7)
Get the mappings right
Exploit the power of constraints, both natural and artificial
Design for error
When all else fails, standardize
(p.199)
Make sure the user can determine the relationships between:
Intentions and possible actions
Actions and their effects on the system
Actual system state and what is perceivable (by sight, sound, feel, etc.)
Perceived system state and the needs, intentions, and expectations of the user
(pp. 199–200)
Use them so that the user feels there is only one way (the right way) to do something
(p.200)
‘The nice thing about standardization is that no matter how arbitrary [it is] you only have to learn it once.’
(pp.200–203)

37. For More … In Preece et al. At website Interview p.59 Chapters 6 & 7
Miniature index of P.O.E.T.
Miniature glossary of Norman’s terms