Psychopathology of everyday Things (Ch-1)imp charac of design: discoverability, understandingareas of design: industrial (form, material), interaction (understandability, usability), experience (emotionl impact)human centric design: focus on human needs, capabilities and behavior first, then design to accomodate themdiscoverability based on following 5 psychological concepts(+1):>affordances (rel. b/w object properties, user capabilities. tell what action can take place)>signifiers (used to make affordances visible. tell where action should take place)>constraints (in Ch-4)>mappings (rel. b/w user action and operation carried out. eg. driving wheel. should be easy to understand, remember)>feedback (communication of results of a user action to the user. clear, visible, informative, unobstrusive)>conceptual model (simple explanation of how something works, shouldn't be based on wrong assumptions)Psychology of Everyday Things (Ch-2)Gulf of execution: how something works (via signifiers, constraints, mappings, conceptual model)Gulf of evaluation: what happened (via feedback and conceptual model)Seven stages of action: goal:-(plan->specify->perform)execution...(percieve->interpret->compare)evaluationhuman thinking: subconscious (fast, automatic, common tasks) and concious (slow, focussed, new tasks) cognitionlevels of cognition:>Visceral (immediate percepttion and reaction, design: affected by style of product)>Behavioural (learned skills, subconscious, design: every action has an expectation, feedback imp, sense of control)>Reflective (assigns causes and predictions, results in emotions like guilt, pride, blame, praise, forms memories, hence imp)emotions and cognition affect each other|GOAL||plan\(reflective)/compare||specify\(behavioural)/interpret||perform\(visceral)/percieve||WORLD|Seven Stages of Action: Questions1. What do I want to accomplish?2. What are the alternative action sequences?3. What action can I do now?4. How do I do it?5. What happened?6. What does it mean?7. Is this okay? Have I accomplished my goal?Seven fundamental Design Principles:Discoverability: discovering possible actions from current device stateFeedback: should be easy to make sense of new stateConceptual Model: should enhance discoverability and evaluation of resultsAffordances: desired actions should be possibleSignifiers: should properly communicate feedbackMappings: should take care of spatial layout and temporal contiguityConstraints: physical, logical, semantic and cultural constraints for guiding actions and interpretationKnowledge in the Head and in the World (Ch-3)Precise behaviour from imprecise knowledge arises because:>Knowledge in both head and world>Great precision not required>Existance of natural constraints>Knowledge of cultural constraints and conventionsKnowledge in the World:>Information is readily and easily available whenever perceivable.>Interpretation substitutes for learning. Ease of interpretation depends upon the skill of the designer.>Slowed by the need to find and interpret the knowledge.>Ease of use at first encounter is high.>Can be ugly and inelegant. Leads to clutter. Skills of the graphics and industrial designer required.Knowledge in the Head:>Readily available. Otherwise considerable search and effort may be required.>Requires learning. Eased by additional structure, good Conceptual Model.>Can be efficient, especially when learned to such a degree that it's automated.>Ease of use at first encounter is low.>Nothing needs to be visible, hence more freedom to designer, at cost of learning.Knowing what to do: Constraints, Discoverability and Feedback (Ch-4)4 types of constraints:>Physical (shape, size, environment, etc. most obvious, major [legacy problem: old, inefficient design persists, because it's always been there])>Cultural (change with time, place, culture etc. [schemas: knowledge structures for cultural behaviour guidelines])>Semantic (constraints derived from meaning of a particular situation, may change with change in culture, technology as well)>Logical (correspond with natural mappings, whatever logic dictates)Forcing Functions: Failure at 1 stage prevents next step from happening. 3 specialized types:>Interlocks: Operations are forced to take place in the proper sequence.>Lock-ins: Keeps operation active, preventing from premature stops.>Lock-outs: Prevents operation from happening when not required.(Sound is an important signifier and feedback, if used properly and naturally without annoyance)Human Error? No, Bad Design (Ch-5)Error: Deviance from "appropriate" behaviour.Root Cause Analysis: Investigation of an accident till a single underlying cause is found. Should NOT stop at human 'error'.The Five Why's: Once a cause is found, don't stop. Ask why that was the cause. And so on.Two types of Errors:>Slips: diff. in intended and performed action. can be action-based or memory-lapse>>Action Slips types>>>capture slips: frequent activity instead of desired, occurs for 'initially similar' actions that diverge. actions should be diff. from start. occurs when distracted.>>>description similarity slips: action upon item similar to target. correct action, wrong object. occurs when stressed. controls etc should be easily differed.>>>mode error slips: occurs when device has diff. states in which same controls mean different things. mode should be visible to avoid confusion.>>Memory Lapse slips: generally occurs because of interruptions. design should minimise such interruptions. also, minimise steps, add forcing function etc.>Mistakes: establishment of a wrong goal. can be rule-based (appropriate diagnosis, wrong rule), knowledge-based (misdiagnosed), memory-lapseSocial pressures (social, economic, schedule-based, culture based etc.) are also a critical factor in errors.Checklists: increase accuracy, reduce error (esp. slips and memory lapses)W.R.T. 7 stages of action: Mistakes (GOAL, plan, compare), Slips (specify, perform, percieve, interpret)Error Reporting and correction examples:>Jidoka (Toyota's error handling method): anyone can report error. if found, others penalised for not reporting. promotes honesty.>Poka-Yoke:adding small conveniences, fixtures, etc to minimise common sources of error. based on forcing functions primarily.>NASA safety reporting sys: semi-anonymous error reports. when submitted to FAA, all contact details removed.Designing for error:>understand causes of error, efforts to minimize them.>sensibility checks ('does it make common sense?')>actions should preferably ne reversible.>errors easy to discover and correct.>treat erronous action not as 'error', but as an approximation of intended action.Swiss Cheese Model: Accident occurs when lots of layers of cheese (layers of ops.) have perfectly lined up holes (errors).To minimise, add layers (more procedural steps), reduce size and number of holes (less safety points)Resilience engineering: design accomdating oncoming problems. equipment, procedures, people continually tested, assessed, improved.Good Design Principles:>Knowledge for operation should be in the world. Aids experts in novel situations and novicesin getting work done easily.>Use natural and artificial constraints, forcing functions and natural mappings.>Bridge the Gulf of Execution and the Gulf of Evaluation. Make things visible, both for execution (feedforward) and evaluation (feedback).Design Thinking (Ch-6)Human Centered Design (HCD): Design should be created for easy use by humans.Double Diamond Model of design: First find the right problem, then the right solution, using HCD principles.Both stages go through steps of divergence and convergence w.r.t alternatives: right problem[(define)], right solution[(deliver)]Steps for HCD: Iterating through observation, idea generation, prototyping, testing.>Observation: of people's requirements, goals, impediments etc. (applied ethnography: observing customers in natural environ to judge needs)>Idea Generation: thinking up potential solutions. required: numerous ideas, avoidance of constraints, question everything>Prototyping: (Wizard of Oz technique: use mock-ups sketches, skits, basically anything quick and easy to whip up)>Testing: Single or in Groups (even for single, preferably in pairs allowing free interaction). Magic number: 5 people.>IterationActivity centered design: Activity defines product, not the people. Works because nost people do similar activities across the world.Activity: High level structure, hierarchial. Task: Low level component of an Activity.Goals have 3 levels: Be-goal (detemines self-image), Do-goal (plans and actions for an activity), Motor-goal (how an activity is performed)Iterative vs Linear Design:>Linear (traditional, waterfall method, no undo. involve decision gates in form of management review)>Iterative (circular, continual improvement. for early stages, since time, money consuming, suitable for small projects)Law of Product Development (by Don Norman :P): The day a product development process starts, it is behind schedule and above budget. (Multidisciplinary teams help)