ONE: OVERVIEW
1. A good design should make atrade-off among follow aspects:
a) Provide a good conceptualmodel, so users can know how the system operate, having a nice system image.
b) Make things visible, so userscan pay attention to the exactly point.
c) Use natural mapping, so userscan map the control and the operation with no effort..
d) Give feedback, so users cancatch the state of the system and if their operation work.
TWO: The psychology of everyday actions
1. Blaming your self: People tendto blame themselves when fail to word some everyday thing, but now we can takeit as a signal to distinguish the bad design.
2. Wrong mental model for lackingexternal information: people always form conceptual models from fragmentaryevidence, basing the models on whatever knowledge in the absence of externalinformation.
3. Blaming the wrong cause: ”Itseems natural for people to blame their own misfortunes on the environment. Itseems equally natural to blame other people’s misfortunes on their personalities.”For exmple:
a) Learned helplessness: “itrefers to the situation in witch people experience failure at a task, oftennumerous times. As a result, they decide that the task cannot be done, at leastnot by them: they are helpless.”
b) Taught helplessness: thelearned helplessness result to some phobias to everyday things. ”if you fail atsomething, you think it is your fault. Therefore you think you can’t do thattask. As a result, next time you have to do the task, you believe you
can’t soyou don’t even try. The result is that you can’t, just as you thought. You’retrapped in a self –fulfilling prophecy.”
4. The nature of human though:Experience will affect how people judge. One has to consider the possibilitythat the instruments are wrong when the instruments indicate that something iswrong. But when operators mistakenly blame the instruments for an
actualequipment failure, the situation is ripe for a major accident.
5. Seven stages of actions: tolead to actions goals must be transformed into specific statements of what isto be done—intentions.
a) Action cycle: World >Evaluation(Comparing what happened with what we wanted to happen) > Goals(What we want to happen) > Execution (what we do to the world ) > world
b) Stages of Execution: Goals >An intention to act so as to achieve the goal > The actual sequence ofactions that we plan to do > world
c) Stages of evaluation: world> perceiving the state of the world > interpreting the perceptionaccording to our expectations > evaluation of the interpretations with whatwe expected to happen > goals
d) Seven stages of actions: world> perceiving the state of the world > interpreting the perception >evaluation of interpretations > goals > intention to act > sequence ofactions > execution of the action sequence > world
6. The gulf of execution: How wellthe system allows the person to do the intended actions directly, without extraeffort: Do the actions provided by the system match those intended by theperson?
7. The gulf of evaluation: thegulf of evaluation reflects the amount of effort that the person must exert tointerpret the physical state of the system and to determine how well theexpectations and intentions have been met.
THREE: Knowledge in the head and in theworld
Make a trade-off between knowledge in world and knowledge in memory.Knowledge in world relieves users from the difficulty in work everyday things.But it may slow how fast users accomplish their goals. Reserve a more effectiveapproach for users with knowledge
in head.
FOUR: Knowing what to do
a) Affordances suggest the rangeof possibilities
b) Constraints limit the number ofalternatives
c) Visibility: make relevant partsvisible
d) Feedback: give each action animmediate and obvious effect
The thoughtfuluse of affordances and constraints together in design lets a user determinereadily the proper course of action, even in a novel situation.
Five: To err is human
Slips: Captureerrors, Description errors, data-driven errors, Associative activation errors,Loss-of-activation errors, Mode errors,