Before Chapter 3Chapter 2 (a bit more)Normans Seven stages of of action Form the goalForm the intentionSpecify the action Execute the actionPerceive the state of the worldInterpret the state of the worldEvaluate the outcome

Before Chapter 3Chapter 2 (a bit more)Connects the seven stages of action to his principles of design:VisibilityGood conceptual modelGood mappingsFeedbackWhich results in these heuristics ==>

Before Chapter 3Chapter 2 (a bit more)Normans heuristics for good designNorman says to ask this: How easy is it toDetermine the function of the deviceTell what actions are possibleDetermine the mapping of intention to physical movementPerform the actionTell if the system is in the desired stateDetermine the mapping from the system state to interpretationTell what state the system is in

DOET 3Knowledge in the headKnowledge in the world

Question of the dayNorman claims that precise behavior is determined by:Knowledge in the headKnowledge in the worldand.. (whats the third thing?)

Precise behaviorThe knowledge required for precise behavior is not all in the head Why?Information (lots of it!) is in the worldPerfect knowledge is not required only just enough to distinguish between the choicesNatural constraints are presentCultural constraints are present

Constraints on behaviorSociety has evolved artificial conventions that operate as cultural constraints.While these have to be learned, once learned, they apply to a wide variety of circumstances.Example: Screws go in with a clockwise turnThe physical properties of objects (natural constraints) constrain possible operations.Things fit together in certain ways that exclude other choicesShape and size determines possibilities

Precise behaviorPrecise behavior is determined by the combination of:Internal knowledge (knowledge in the head)External information (knowledge in the world)Constraints (natural and cultural)

The world(The environment)Provides constraints that shape behaviorCan be organized to support behaviorPut the book you need to return against the front doorPut your keys inside the thing that you must take home with you

Knowledge in the world

Need not be memorized BUT: Must be read and interpretedIs more time consuming to accessIs only available when you are where it is

Knowledge in the worldMay not result in fluent behavior (example: typing)Relying on the knowledge in the world (hunt and peck typing) will work but is slowTransfer that knowledge to the head (by learning what movements result in what letters) speeds performance

Interesting side effects:Knowledge in the world;Knowledge in the headTypists cannot arrange keyboard keytops in their proper order.We cannot pick out which picture of the penny is accurateHerb Simons SatisficingWe learn just enough to get the job done

Interesting side effects II:A chess master can memorize a chess board layout but they are better than most ONLY if it is a layout that can be legitimately arrived at by following the rulesFreshmen at Emory were surveyed the day after the first shuttle disaster and then again as they graduated. The more certain they were right, the greater chance they werent

Head vs WorldHerb Simons ant on the beach parableThe path that an ant takes as it crawls across the beach is complex.Where does this complex behavior come from?Is it in the head of the ant? Is it even possible for something as small as an ants head to contain such complexity?Is it the complexity of the beach being acted on by the simple ant?

Kinds of KnowledgeProcedural knowledgeKnowledge of howHard to write downHard to teach (usually must be demonstrated)Apprenticeship works well hereDeclarative knowledgeKnowledge ofEasy to write downEasy to teach

Using a structured environmentPhysical arrangement in the world relays information about the relative importance of those items in the world.Visibility (or lack of visibility) also relay the relative importance of items.Placement can serve to enforce a particular sequence of eventsPlacement can serve to enforce a particular timing of events

Precision required?People store partial descriptions of objects in the world (models of those objects)The French coin exampleIt was different, but not different in ways that the public used to distinguish coin differences

Precision required?These models are sufficient to solve the problems for which they were learnedCan differ from person to personBy definition these models are not completeSometimes they will work on future novel situations, sometimes they will failGives credence to the saying to a man with a hammer, everything looks like a nail

Monday!

ConstraintsRhyming is a way of constraining possible choices, making memorization of easier.Combined with meaning, rhyming almost completely specifies the word choicesStory tellers dont memorize the story, they memorize the characters, the plot and the rhyming scheme and recreate the story each time. (They store a model of the story)

Structure of human memoryLong term memoryPermanentUnlimitedTakes work to accessyou know that you know the answer but it doesnt come to you until the next dayShort term memoryFleetingVery limitedImmediately available

Wednesday

Long term memoryOne problem is organizationalYou are trying to think of a name but you keep coming up with another name that you know is the wrong nameAnother is representational (the model used)Representational can be broken into categoriesMemory for arbitrary thingsMemory for meaningful relationships (the switch moves in the direction that the handlebar moves)Memory through explanation (the development and use of an internal model)

Memory for arbitrary thingsAKA Rote learning; has problems:Difficult to doErrors are not made evident by the sequence of actions because they are arbitraryPeople like structure (models) and manufacture them even when they do not exist (is this why acronyms work so well as a learning prop?)Reuse of these manufactured models results in inaccurate behavior

Memory for arbitrary thingsAKA Rote learning the concept of chunkingSocial security numbers and Phone numbers are broken into groups of 2, 3 and 4 numbers for a reasonWhich is easier to remember?4042245509or404 224 5509433600918or433 60 0918

Memory for meaningful relationshipsA sensible structure (natural mapping) simplifies memory taskMotorcycle turn switch example which was solved by reinterpretation of the mappingOn left handlebarForward is right Back is leftReinterpret from its on the left so forward is left to the switch movement maps to handlebar movement

Memory through explanation People are explanatory creaturesWe make stuff up just to help us rememberIf asked, most people will give you an answersometimes what is NOT said is more important than what is said (subjects, dogs & religion)Mental models simplify learning because the details can be derived from an appropriate modelModels are powerful when they are complete enough to allow them to be used to solve novel problems

RemindingTwo aspects of remindingThe signal The messagePersonal importance makes it more certain that you will remember to do something in the future (prospective memory)Place the reminding burden on the thing itself

Mappings and stovesMake the organization of the controls carry the information needed to successfully execute the behaviorHint: If labels are needed, the design may be faulty

Knowledge in the world;Knowledge in the headSummaryKnowledge in the world Acts as its own reminderEasier to learnHarder to useRelies on being in the environmentKnowledge in the head Is more efficientMay require extensive learningMay need external triggering

Concepts discussed thus far:(An incomplete list to be expanded later)You will need to know what these are and how to use them

The End!