1. DOET Chapter 1 Models, Modes, Execution and Evaluation
ITEC4130
Dr. Jim Rowan

2. Today’s Question:
Name the two Gulfs discussed by Don Norman

3. Stuff in the world DVDs Cell phones Automobiles
Student IDs with RFID chips
Turn arrow at PepBoys on JimmyCarterBvd

4. Poorly designed objects
Difficult to use
Don’t provide clues as to their use
EVEN WORSE: Provide false clues.
Have hidden modes of operation
Generally unpleasant to use, unfriendly…

5. Well-designed objects
Easy to interpret
Easy to understand
Provide clues as to their use

6. Why does this happen? (My personal opinion: Up for discussion)
For objects in the natural world: form follows function
For objects in the man-made world form can be completely disassociated from function
Made worse by the transition from the mechanical to the electronic
Mechanical objects are visually inspectable
Electronic objects are NOT visually inspectable

7. The glass door trap

8. Design principle: Visibility and the GlassDoors
Correct parts must be visible
If they aren’t how do you know what to do?
Parts must convey the correct message
Mappings: Does what the object tells you about how to use it (through the parts it shows you) match your expectations of those parts?

9. Hidden mappings The Leitz slide projector control
Only one button but two operations
Not designed for intuitive use
Not designed for explorative use either
Does it violate Norman’s Visibility?
Does it violate Norman’s Mapping?

10. The phone example in book
Instructions were written in the language of the designer not the language of the user
The hold function lacked results visibility:
Was the call I just put on hold actually put on hold or was it disconnected?
Other phones flash a light beneath the hold button (at least it connects the flashing light to the button that activated it)

11. The phone Did you know… Dial tone was an intentional addition
Made the invisible (do I have a connection?) visible
It tells you that you can start dialing

12. Norman’s Principles Visibility Appropriate clues
Feedback of one’s actions

13. Affordance and Causality
The perceived and actual properties of a thing that determines how it is used.
Affordances are strong clues.
Correlation does not imply causation
Though as humans we REALLY want it to!
Temporal correlation implies causality
Can give rise to superstition

14. Affordance and Causality
For push buttons (especially the remote)
Sometimes they click
Sometimes a light flashes
The lack of expected temporal correlation gives rise to repeated action
Like an idiot, you keep pushing the button hoping to eventually get something to happen
You end up causing an error… or deleting an entire season of CSI!

15. Projected keyboards Why? You don’t have to carry them with you!

16. Projected keyboards…
What are the problems?
my answers next slide

17. Projected keyboards… fingers block the display
no audible click (can be added with software
no physical movement
no physical feedback on finger positioning
room lighting

18. Projected keyboards…
Possible partial solutions?
my answers next slide

19. Projected keyboards… (partial solutions)
software generated “click”
the typed word appears on the screen
What about solving the finger position problem? (not so easy)

20. Tiny keyboards… affordance issues
Problem:
fingers hide keyboard?
show the selection larger

21. Where do user expectations come from?
Some are cultural
Some are explicitly learned (standards)
cold water is on the right
hot water is on the left
Some may be basic to humans
The attraction of the campfire…
The beauty of the arch as a basic form…

22. Clues from visible structure
Affordances
Constraints
Mappings
Consider scissors
Holes in the handles afford insertion
Hole size constrains what can be inserted (fingers, maybe; legs, probably not.

23. Models, Mental and otherwise
Three different models
Design model: The designer’s conceptual model.
System image: The model implied by and presented by the device’s structure
User’s model: The mental model you hold that guides your actions

24. Models, Mental and otherwise
Consider the refrigerator
the visible controls (the system image) imply two separate systems
in actuality it is only one system
Errors arise when the user (using his mental model implied by a flawed system model) tries to operate the system

25. But: Who’s Model is it really?
The designer has a model when creating a device
The user has a model when trying to use a device
The system image is how the designer communicates with the user; It’s the device’s physical and operational form.
You (as the designer) are most probably NOT the user so you’d better know the user!

26. Hidden Mode Problems
A mode is a change in context that affects the interaction with a device.
A button means one thing in one mode and something different in another mode
Many features with few controls give rise to hidden modes
“featuritis”
Modes must be made visible

27. Hidden Mode Problems Airbus 320 was a mode problem
pilot was doing a flyby
the airplane was doing a landing
Flying into the Everglades:
A tale of human attention/distraction
Going off autopilot was silent

28. The Good Visibility Natural mapping from control to controlled
Feedback
Number of controls = number of functions
or make certain the modes are visible

29. The Bad Hidden modes Arbitrary mappings False conceptual model
The forklift!
False conceptual model
The refrigerator
Many functions, few controls
cell phones

30. Natural Mappings
Relationship between controls and actions are apparent to the user
Spatial analogy: Up on the control is up
Cultural or biological (rising level is more)
Additive (loudness, brightness)
Substitutive (increasing pitch is more)

31. Feedback: Good! Tactile feedback (keyboards… )
Auditory feedback (keyboards, phones…)
Visual feedback (pencil, changing lights…)

32. Why are there so many bad designs?
Multiple stakeholders in a design venture
Designer
Manufacturer
Retail outlet
Purchaser
Maintenance

33. Technological Paradox
Technology provides more functionality; possibly reducing the number of devices needed
More functionality increases complexity
Making it more difficult to learn
Making it more difficult to use
So… Life’s simpler but more complicated!
Creeping featurism: Attractive but deadly!

34. Picking up from last class:

35. Human Error? You use a device and continually make the same mistake…
Is it your fault?
Is it the device’s fault?
Is it the designer’s fault?
Yes to all three… but knowing what mistakes humans are subject to make allows the designer to avoid them.

36. Folk Theory and Home Heating Thermostats
Humans want causality!
Naïve theories abound.
The timer theory: Half way is half the time.
The valve theory: Half way is half open.
Truth: It’s on full blast or it’s off.

37. Norman’s Structure of Action
To get something done you need:
A goal to achieve in that world
A world in which to act
Then take action:
Make a change in the world
Check the world to see if the goal has been met

38. Goals
Goals are Underspecified: They don’t tell precisely what is needed to be done to accomplish them
Get dressed
Go to work
Drive home

39. The Action Cycle: Two types of Actions
Execution
Make a change in the world
Evaluation
Check the world to see if the goal has been met

40. Stages of Execution Form the intent to act on the goal (mental)
Form the action sequence required to achieve that goal (mental)
Execute that action sequence (physical)

41. Stages of Evaluation Perception of the world as it is after execution
Interpret that perception according to our expectations
Evaluate the interpretation against our intentions and our goals

42. Goals World Intentions Action sequence Execute
Evaluate interpretations
Interpret perceptions
Perceive the state of the world
World

43. Norman’s Seven Stages of Action
Form the goal
Form the intention
Form the action sequence
Execute the action sequence
Perceive the state of the world
Interpret the perception
Evaluate the interpretation against expectations

44. Everyday Tasks a class of tasks we all do all the time in the course of each day
Humans are Opportunistic in nature
They take advantage of circumstances
Implies that action is triggered by opportunity
Use the environment to trigger activity
Not necessarily planned in advance
you are reminded as you walk around that…
the dishes need washing
you need to shop for groceries

45. Gulf of Execution
The difference between the intentions on the part of the human and the allowable actions on the part of the system
VCR bridges the gulf of execution found in the reel-to-reel videotape machines… there is no way to foul up the threading the machine.

46. Gulf of Evaluation
A measure of the amount of effort on the part of the user needed to interpret the state of the device and determine if (or how well) expectations have been met.
VCR: Can’t tell if a tape is in the machine. Press play and it just sits there (in some models)

47. Norman’s Principles of Good Design
Visibility: Can the state of the machine and the possible available actions be easily determined by inspection?
Good conceptual model: Is the system image a good one for the intended users?
Good Mappings: Are there ties between actions and results? Controls and effects?
Feedback: Does the user get feedback from the results of actions taken.