This document summarizes key concepts from chapters 2-4 of Donald Norman's book "The Design of Everyday Things". It discusses the 7 stages of action, different types of knowledge, and how constraints and affordances help users understand how to interact with technologies. The types of constraints covered are physical, semantic, cultural, and logical constraints. Various tweets from students discuss examples and applications of these constraints.

1. Comm / INFO 2450
Communication and Technology
Professor
Drew Margolin

2. 2450 in the News

3. Review

4. Goals
Evaluation of
the interpretations
Interpreting
the perception
Perceiving the state
of the world
Intention to act
Sequence of actions
Execution of the
action sequence
The World
Chapter 2 – The Psychology of Everyday Things
The Seven Stages of Action
GULF OF
EXECUTION:
How much do I
need to know to do
what I want?
GULF OF
EVALUATION
How hard to I have
to look to see if I
did it?

6. Chap 3 – Knowledge in the Head and in the World
Declarative vs. procedural knowledge
Information in the head
Information in the world
Great precision is not required
• Natural constraints
• Cultural constraints
Reminders

7. Chap 3 – Knowledge in the Head and in the World
Declarative vs. Procedural Knowledge
Declarative – knowing that. Knowledge you can put into words
Procedural – knowing how. Knowledge you can put into actions

8. Chap 3 – Knowledge in the Head and in the World
Declarative vs. Procedural Knowledge
Norman’s take:
1. Conveying procedural know how via declarative statements is inefficient
2. People have substantial procedural knowledge capacity
3. Both kinds of knowledge are aided by
• Relationships (physical and mental)
• Constraints (natural and cultural)

9. Chap 3 – Knowledge in the Head and in the World
Information in the head - memory
• memory for arbitrary things
• memory for meaningful relationships
• memory through explanation (mental models and novel situations)

10. Chap 3 – Knowledge in the Head and in the World
Information in the world
• physical, symbolic or social cues that
• guide behavior (procedural)
• provide knowledge or prompt memory (declarative)
hbianchi2450: I take 'knowledge in the world' for granted. Without street
signs or written reminders in my planner, I wouldn't survive!
mrothstein2450: In high school I kept my gym locker combination under a
contact named 'Jim' ... I guess I'm not as cunning as I thought

11. Chap 3 – Knowledge in the Head and in the World

12. Chap 3 – Knowledge in the Head and in the World
Perfect precision is not required
• only need to narrow down the choices enough to ensure the right one
sharrison2450: Minimal knowledge to get by: I don't know most of my
friends' last names even if we're fb friends. I rely on profile pictures

13. Chap 3 – Knowledge in the Head and in the World
How do we narrow things down?
Constraints!
rattia2450: Growing up, I thought I was a master #LEGO builder... Now I
know the makers of #LEGO were one step ahead of me #constraints

14. TweetReport

15. TweetReport
Physical Constraints
jswannie2450: the physical constraints for USB drives should be more
visible so that I don't have to flip it several times to make it fit

16. TweetReport
Physical Constraints
kmiller2450: my sister has to bypass interlock on lawn mower and put brick
on spring-loaded switch or it won't turn on bc she's too light
May only work for some users!

17. TweetReport
Cultural Constraints
julisilva2450: Can cultural constraints be partly to blame for taught or
learned helplessness?
jwegener2450: As long as a Cultural Constraint isn't breaking the law, is it
really a constraint? People break 'social norms' all the time.
llewis2450: I wonder if social networking has impacted what is considered
a cultural restraint.

18. TweetReport
Semantic Constraints
jobrien2450: all the clues depend much on culture and reminded me of
Buddy from Elf https://t.co/xzVphsnYTG #awholenewworld

19. TweetReport
Audible Visible
mneborak2450:: I am a supporter of audio feedback, because visual
feedback can clutter a space and make the correct action unclear.

20. How do people figure out what to do with a technology?
What kinds of cues / signals can designers provide?
What should a designer take into account?
Chapter 4 – Knowing What to Do

21. What is a constraint?
Chapter 4 – Knowing What to Do

22. What is a constraint?
Constraint – something which user can’t do or wouldn’t try
• Physically impossible, or much more difficult
• Socially prohibited
• Nonsensical or incompetent
• Logically / mathematically deducible
Chapter 4 – Knowing What to Do

23. Constraints vs. Affordances as cues to action
Different ways of getting to a manageable but useful number of choices
• Affordances – encourage particular possibilities
• Constraints – rule out / discourage other possibilities
Chapter 4 – Knowing What to Do
znan2450: iPod shuffle is simply designed that what can
be done is limited, and raised buttons afford pressing.

24. Chapter 4 – Knowing What to Do
Hhahn2450: I always viewed constraints as negative, but they can actually
help guide you by clearing things/options away.
Value of constraints
Information Theory (Claude Shannon)
More possibilities  more uncertainty (also known as “entropy”)

25. Value of constraints
Information Theory (Claude Shannon)
More possibilities  more uncertainty
Chapter 4 – Knowing What to Do

26. Value of constraints
Chapter 4 – Knowing What to Do

27. The King of Constraint
[Google Screen Shot] [Bing Screen Shot]

28. The Competition

29. The Competition – Two Years Ago

30. The Competition -- Now

31. Do They Still Have a Search Engine?

32. Overly constrained, causing confusion and annoying user!
Chapter 4 – Knowing What to Do

33. Kinds of constraints
Physical constraints
• Speed
• Size
• Shape
• Effort
• Energy
Chapter 4 – Knowing What to Do
jsong2450: I've definitely experienced physical constraints when i try jam my
keys into a keyhole obviously too small
HAjmani2450: My juicer has to be assembled before use and 2 different
pieces have the same physical constraints. Juice goes everywhere

34. Physical Constraints
What are the glasses telling the user
about how they should be used?
Chapter 4 – Knowing What to Do

35. Physical Constraints
What are the glasses telling the user
about how they should be used?
Or, how is this design different?
Chapter 4 – Knowing What to Do

36. Kinds of constraints
Physical constraints
Semantic constraints
• Derived from the “meaning” of the situation or purpose of technology’s use
• determines competent actions, rules out “silly” actions
• What the technology “expects” the user is trying to do
Chapter 4 – Knowing What to Do

37. Reducing ambiguity via semantic constraint
Chapter 4 – Knowing What to Do

38. Semantic constraint is important to organizational and product success
Sometimes called “core concept,” “use case” or “mission”
• Provides clear rules for organizational decisions
• Easier for customers to evaluate
• Improves designer – user communication
Chapter 4 – Knowing What to Do
gahmed2450: New self-driving concept cars aren't bound by the same
semantic constraints as before. Now all the seats can face each other.
And what else…?

39. Kinds of constraints
Physical constraints
Semantic constraints
Cultural constraints
• Derived from social norms of acceptable, appropriate action
• Scripts, typical habits of action in a culture
• Prohibited actions, things people “wouldn’t do”
Chapter 4 – Knowing What to Do

40. Cultural Constraints
Most social media rely on cultural constraints to police users
Chapter 4 – Knowing What to Do
kzhou2450: #CulturalConstraints #prevent #people #from #doing #stupid
#stuff #like #this #or #at #least #I #hope #so #hashtag
Is the 140 character limit really a constraint?

41. Kinds of constraints
Physical constraints
Semantic constraints
Cultural constraints
• Derived from social norms of acceptable, appropriate action
• Scripts, typical habits of action in a culture
• Prohibited actions, things people “wouldn’t do”
Chapter 4 – Knowing What to Do
kbrown2450: even though baseball gloves make good hats it seems pretty
obvious how they are supposed to be used... cultural constraint?
This is more based on affordances. The primary constraint is not
cultural

42. Kinds of constraints
Physical constraints
Semantic constraints
Cultural constraints
• Derived from social norms of acceptable, appropriate action
• Scripts, typical habits of action in a culture
• Prohibited actions, things people “wouldn’t do”
Chapter 4 – Knowing What to Do
bschiff28: I still struggle every time I use chopsticks #CulturalConstraint
fgulotta2450: As an AEM major, I see a lot of examples of cultural
constraints. A popular one: the Chevy 'Nova' did not sell well in Mexico

43. Kinds of constraints
Physical constraints
Semantic constraints
Cultural constraints
Logical constraints
• Derived from eliminating some of a fixed set of choices
Chapter 4 – Knowing What to Do
rpicard2450: Funny how 'logical constraints' is a separate clue into design.
All of this discussion kind of seems like 'logic' to me
mnelson2450: Most of the time I only know to push a push-door and pull a
pull-door because of logical and physical constraints.

44. Chapter 4 – Knowing What to Do
Logical Constraints
Something logical about light switches?
(Norman would be aghast)

45. Your Groups
Graduate TAs
Marina Filkin
mf453@cornell.edu
Lucy He
lh486@cornell.edu
Emma Lichtenstein
ejl227@cornell.edu
Franccesca Kazerooni
fk235@cornell.edu
Angel Liu
yl839@cornell.edu
Vincent Yu
cy395@cornell.edu
Amanda Loesch
ajl338@cornell.edu
Rachel Goldman
rcg84@cornell.edu
Jason Cogan
jdc356@cornell.edu
Darra Loganzo
dsl236@cornell.edu
Red Group Green GroupBlue Group
Ruth Weissman
raw287@cornell.edu
Stefanie Wu
scw87@cornell.edu
Gabrielle Stadlen
gss78@cornell.edu

46. For Next Class
• Read Zanella et al.
– Only pages 22 – 25 (stop at end of Section II)
• If you like to pre-read before the lecture
– Read Norman Chapter 5 in version on BB (skip the
part about the “types of error”)
• But you will only be tested on material
covered in lecture (as though you had not
read it)

47. END