Don Norman’sDOET
Jim RowanGeorgia Gwinnett College
ITEC 4130
Don Norman’s fundamental principles of
designing for humans Provide a good conceptual model Make things visible Provide good mapping Provide feedback
Don Norman’s fundamental principles of
designing for humans Provide a good conceptual model Make things visible Provide good mapping Provide feedback
What’s a conceptual model?
Designer’s conceptual model is built into the device
System image is what the device shows the user
User’s conceptual model is how the user interprets the system image
Q: Does it match the system’s actual functioning?
Different conceptual models
The system image
The user’s model
The actual underlying model
Don Norman’s fundamental principles of
designing for humans Provide a good conceptual model Make things visible Provide good mapping Provide feedback
Make things visible
Just because it is available to be seen doesn’t mean you are going to see it– Apollo 13 for example
Don Norman’s fundamental principles of
designing for humans Provide a good conceptual model Make things visible Provide good mapping Provide feedback
Good mapping
Natural mapping– Physical analogy
• Louder or softer• Rising level or lowering level• Movement direction as pointer
– left points left– right points right– up points up – down points down
Good mapping
Natural mapping– Cultural standards
• Red is stop• Green is go• Yellow is caution
Parroting the shape:One way to support mapping
What does it mean?
You have to memorize a mapping for this: left is back?
If the wheel was vertically placed it might be easier to invent the mapping: Up is forward
Start Here
Don Norman’s fundamental principles of
designing for humans Provide a good conceptual model Make things visible Provide good mapping Provide feedback
Feedback
When you pick up your phone to make a call you wait until you get a “dial tone”
This dial tone is intentionally provided feedback
The Bell system wanted the user to know when he is connected and allowed to dial
Feedback
Feedback of what?
– Feedback of possible actions to be taken?• Norman’s Execution
– Feedback to show the result?• Norman’s Evaluation
Feedback
Compare the magic marker and board to chalk and chalk board…– Marker proclaims it’s existence– Chalk also proclaims it’s existence– Which tells you that it is going to be
usable? That’s feedback
Humans are explanation seeking
We want to explain why things happen
This is why correlation is frequently mistaken for cause and effect
When you are explaining things you are forming a (possibly faulty) cognitive model of the way things work
Humans look for “reasonable” explanations
L1011 is a 3 engine aircraft One engine shows low oil pressure and
gets cut off Eight minutes later the remaining two
engines show low oil pressure and get cut off
Crew didn’t want to believe it “Million to one” so it’s not reasonable Why?
Explaining the L1011
Crew can’t understand how 3 engines can fail simultaneously
But… they were thinking of the engines as independent units but…
There was an unseen connection between the 3 engines– They were all 3 overhauled at the
same time!
Faulty explanations:Naïve physics; Running man
Q: Why is Summer hotter?
Nature of human action
1)We look at the world
2)We compare it to what we want
3)We form goals to make it happen
4)We take actions to achieve those goals
5)Go back to 1
Nature of human action:Execution
As you move down on the graph, you get more specific
•Form the goal: •Build a house
•Form the intention: •To build a house I need to:
•Apply for loan•Look for a lot•Look for a house plan •Look for a contractor
•Form the action sequences required•Look online for loan providers•Contact a real estate agent•…
•Actually carry out the actions•Fill out loan applications•Attend appointments to view lots•…
Nature of human action:Execution
As you move down on the graph, you get more specific
•Form the goal: •Get an undergraduate degree
•Form the intention: •?
•Form the action sequences required•?
•Actually carry out the actions•?
Nature of human action:Evaluation
•As you move up on the graph, you get less specific
•Perceive the current state of the world
•Do I own a lot?•Interpret the perception by comparing results to expectations
•No I’m still looking•Evaluate the interpretation
•I don’t have a lot so I’ll have to continue looking for one
•Since I don’t have a lot, clearly I haven’t reached my goal of buying a house.
Putting it all together:Norman’s 7 stages of action
•Form the goal•Form the intention•Specify the sequence of actions•Execute the actions•Perceive the state of the world•Interpret the state of the world•Evaluate the interpretations
•Have I met my goal?
Restart here on wednesday
Knowledge in the head;Knowledge in the world
•There’s more knowledge in the world than you might imagine
•Humans are lazy… on purpose•There’s too much going on in the world to pay attention to everything so we are selective•We learn just enough to do what we need to do
• Herbert Simon called this “satisficing”•http://en.wikipedia.org/wiki/Satisficing•What good is the right answer if it comes too late to help you solve the problem?
Herbert Simon
He pointed out that human beings lack the cognitive resources to optimize: •we usually do not know the relevant probabilities of outcomes•we can rarely evaluate all outcomes with sufficient precision•our memories are weak and unreliable
•A more realistic approach to rationality takes into account these limitations•This is called bounded rationality.
Strategies that take advantage of satisficing
Don’t sacrifice the “good enough” answerIn a search for the perfect answer
POGE: Principle of good enough http://en.wikipedia.org/wiki/Principle_of_good_enoughWorse is better:http://en.wikipedia.org/wiki/Worse_is_BetterThe reverse of this is Featuritis:http://en.wikipedia.org/wiki/Featuritis
Knowledge in the head;Knowledge in the world
There’s more out there than you might imagine
Knowledge in the head;Knowledge in the world
There’s more out there than you might imagine
That’s why context is so important
Many times context provides the actual meaning
This is one reason that moving an aging person to an elder care facility can be so traumatic for the aging person… their living arrangements provide the context to their lives… it provides them with clues to who they are and how they live
Knowledge in the head;Knowledge in the world
Heuristics for the 7 steps
What’s wrong here?
How does this fix it?
Making controls look different:That’s the problem in the Pixar
short we saw earlier
Types of task structure
What is the structure of the task you are asking the user to carry out?
Deep– Many simple decisions
Shallow– A single more complicated decision
A deep task structure
A shallow task structure
Interlocks and
forcing functions
Physically block one action by placing the first task in the way of the second
Lockout form of forcing function
Overcoming task
complexity through
organization
Mappings
Is making something easy to do always the
goal? What about
game design? What about in
specialized environments?
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