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Unit 3 The Design of Everyday Things Professional Development II PSYC 4170 Part 4: Knowing what to do: Constraints, Discoverability and Feedback Michael J. Kalsher
We often combine knowledge-in-the-world with knowledgein-the-head to operate something we’ve never seen before. KITW • Perceived affordances and signifiers • Mappings between control parts and resulting actions • Physical constraints limiting what can be done KITH • Conceptual models • Cultural, semantic and logical constraints on behavior • Analogies between new situation and previous experience
Experiment: Building a Lego Motorcycle The LEGO motorcycle set has 15 pieces. Some pieces are physically similar and so physical constraints aren’t sufficient. But the appropriate role for every piece is determined through a combination of cultural, semantic and logical constraints with the physical ones. No one typically has any difficulty. Why? Visible affordances (cylinders, holes, sizes, shapes) Physical constraints (limit what parts fit together) Cultural and semantic constraints (provide strong restrictions on what makes sense for all but one part) Logical constraints (dictates placement of remaining part)
Kinds of Constraints Physical Cultural Semantic Logical
Physical Constraints (limit possible operations/actions) Most effective/useful if easy to see/interpret Example: Design of batteries and battery compartments and the Legacy problem
Microsoft Insta. Load lets you insert batteries in any direction (Gizmag Team, July 1, 2010) • • • For batteries to work, they need to go in the right way. It's one of those fundamental rules that we all pick up from an early age, but Microsoft has just announced an innovation that turns all that on its head – literally. Known as "Insta. Load" battery installation, the technology allows you to insert a battery without having to worry about positive and negative polarity. That's idiot-proofing of the highest order! Insta. Load is designed to save time when using portable devices that need regular battery swaps and would have obvious benefits for (the many) poorly designed gadgets out there that require a microscope to see the polarity diagram. Microsoft says that "unlike existing electronic solutions designed to address batterypolarity installation, Insta. Load is a mechanical invention that does not drain battery power or require expensive electronic circuitry. " The contact system is suitable for most devices that have barrel-type compartments and use CR 123, AAA, C or D size batteries (disposable or rechargeable). Microsoft is licensing the patented battery contact design and Duracell is among the companies looking to make use of the technology. Idiot-proofing cracks aside (I know I've managed to put batteries in backwards many times), there is also clear benefit here for people with hearing, vision or learning disabilities. Microsoft has recognized this and is offering a royalty-free license program to suppliers and manufacturers of accessibility devices.
Cultural Constraints (the set of allowable actions in a social situation) Cognitive science term = Scripts (Schank & Abelson) Sociologists term = Frames (Erving Goffman) Examples: “Knowing” how to behave in a restaurant or in a group of strangers. While riding in an elevator, try standing near the door facing the other riders!
Semantic Constraints (rely on the meaning of the situation to control the set of possible actions) New technologies change the meanings of things Consider the case of fully automated vehicles. What would red lights on the rear of the auto mean? That the car is braking, but for whom would the light signal be intended? The other (fully automated) cars would already “know”.
Logical Constraints (logical relationship between spatial/functional components and things they affect) Remember the LEGO example? The blue light presented a problem, as many people had no knowledge that would help, but after all the other pieces were assembled, there was only one place for it to go—it was logically constrained. Putting together a gas grill. If there are leftover parts, obviously there was an error!
Constraints that force desired behavior Forcing functions: a form of physical constraint for situations in which the actions are constrained so that failure at one stage prevents the next step from happening. Interlocks: forces operations to take place in a sequence. 1. Microwave ovens: Power shuts off if door is opened. 2. Autos with automatic transmissions: interlock prevents driver from shifting out of the Park position unless the brake is depressed. 3. Dead man’s switch (e. g. , the spring-loaded switch beneath the seat of lawn tractors and heavy equipment).
Forcing functions Lock-ins: keeps someone in a space or prevents an action until the desired operations have been done. 1. Computer applications (e. g. , a message prompt, such as “Do you want to save the changes made to …”, to confirm the user’s selected action). 2. Literal “lock-ins”(e. g. , jail cells; playpens for babies prevent the person from leaving the area).
Forcing functions Lock-outs: prevents someone from entering a space that is dangerous, or prevents an event from occurring. 1. Ground floor stairway gates prevent people rushing down the stairs from entering the basement where they might get trapped. 2. Baby lock-outs (e. g. , for cabinet doors; electrical outlets; childproof caps; fire extinguisher pins). 3. LOTO (lock-out/tag-out) Note: Should minimize the nuisance value of lock-outs to reduce the chances people will disable them.
Conventions: A special kind of cultural constraint Example: The means by which people eat is subject to strong cultural constraints and conventions.
Conventions: Destination Control Elevators Despite advantages, catching on slowly—people hate change (think about the metric system). How do they work? • Desired floor is entered into a control panel outside the elevators. • Panel display directs travelers to the appropriate elevator. • Inside controls are limited to “open/shut” doors and an alarm. Portigal, S. , & Norvaisas J. (2011). Elevator pitch. Interactions, 18(4, July), 14 -16. http: //interactions. acm. org/archie/view/july-august-2011/elevator-pitch 1
Conventions: Water faucets People really care about two things—temperature & rate of flow. The fact that water enters a faucet through two pipes (hot and cold) creates a conflict between the need for temperature and flow control and the physical structure of hot and cold. How best to handle this? If all else fails, standardize. With traditional dual faucet controls for hot and cold water, the standards should state: • When the handles are round, both should rotate in the same direction to change water volume. • When the handles are single blades, both should be pulled (toward the user) to change water volume (which means rotating in opposite directions in the faucet itself).
Using Sound as Signifiers • Can be very useful (rattling sounds when things are unsecured; whistle of a tea kettle; increased pitch when a vacuum cleaner gets clogged). • Positive and negative characteristics: • Omnidirectional, annoying/distracting; difficult to localize/keep private • Its absence can be deadly … electric/hybrid vehicles.
Not everyone agrees there is a problem https: //forums. tesla. com/forums/newregulation-electric-and-hybrid-vehicles
HF Principles for (EV/HV) Sound Design • Alerting: The sound will indicate presence of an electric vehicle. • Orientation: The sound will help make it possible to determine where the vehicle is located, a rough idea of its speed, and whether it is moving toward or away from the listener. • Lack of annoyance: These sounds will be heard frequently and continually and so should not be annoying. Sirens, horns and backup signals are deliberately unpleasant but (relatively) infrequence and of shorter duration. • Standardization vs. individualization: Must ensure that all electric vehicle sounds can readily be interpreted in a consistent way. Question: What role will the concept of skeumorphic (incorporating old familiar ideas into new technologies) play in developing sound for electric and hybrid vehicles?
http: //www. nhtsa. gov/Sample. Sounds