UX 모임 2018-10-22

UX 모임

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• 살펴볼 사이트:

The Design of Everyday Things Ch. 4 - Knowing What to Do: Constraints, Discoverability, Feedback

• How do we operate something new? --> Knowledge in the world (affordances, signifiers, mappings, constraints) and knowledge in the head (conceptual models, analogies to previous situations)

Four Kinds of Constraints: Physical, Cultural, Semantic, and Logical

Physical constraints

• Limited number of actions
• Desired action made obvious
• Restriction prior to any action being taken (to prevent wrong action before it happens)
  • Battery design; USB design?
• Legacy problem: too many devices use the existing standard
  • Expense of change?
  • Corporate thinking - not caring about the customer

Cultural constraints

• Each culture has a set of allowable actions for social situations
• Ex: Restaurant, public transportation
• Can change over time

Semantic constraints

• The meaning of the situation controls the set of possible actions
• Can change over time

Logical constraints

• After all other options, what is left?
• Obvious errors
• Natural mappings help here

Cultural norms, conventions, and standards

• Greetings with people, traffic laws, food etiquette
• A form of cultural constraint
• Sometimes become international standards or laws
• Violate conventions, and you are marked as an outsider

Applying Affordances, Signifiers, and Constraints to Everyday Objects

The problem with doors

• Sometimes unclear how to use - where to push, push or pull, automatic or not, etc.
• Focus on aesthetics may blind the designer/purchaser to the lack of usability
• Cultural norms play a role

The problem with switches

• Can be annoying... or dangerous
• Must know: 1) what they control, 2) mapping (which they control)
• More switched --> more danger
• Problem comes from coordination of various professions
• Phone/computer applications for this may solve the problem; touch screens, cameras which recognize gestures?

Activity-centered controls

• video, comptuer, full ights, lecture, etc.
• can be done poorly
• device-centered is a wrong approach - different switches/screens for different devices
• regardless, manual controls will still be required because of new, unexpected, demands which require idiosyncratic settings
• manual setting should not cause the current activity to be canceled

Constraints That Force the Desired Behavior

Forcing functions

• a kind of physical constraint: situations in which the actions are constrained so that failture at one stage prevents the next step from happening
• ex: car keys

Interlocks

• Forces operations to take place in proper sequence
• Press down brake pedal to switch out of park
• "Dead man's switch" - user must hold down switch during use so that if they die/are injured the operation stops
  • lawn mower, chainsaw, etc.

Lock-ins

• Keeps an operation active, presenting someone from prematurely stopping it
• Ex: "Want to save file?", jail cells, play pens
• Devices which only are compatible with the company's other devices

Lockouts

• Prevents people from entering a dangerous space or prevents an action
• Barrier between ground floor and basement for fire safety

Conventions, Constraints, and Affordances

• From perception of an affordance to understanding the potential action relies on conventions
• Ex: doorknob

Conventions are cultural constraints

When conventions change: the case of destination-control elevators

People's responses to changes in conventions

• People complain, new learning is required
• The merits don't matter, the change does
• Ex: metric system and the U.S.

The Faucet: A Case History of Design

• How to deal with hot and cold
  • Separate not and cold? Only temperature? Only amount? On-off?
• Which is hot/cold? How to change temp? How to change flow? Which direction controls flow?

Using Sound as Signifiers

• Useful signifier, but can annoy/distract
• Silence can be dangerous
  • Ex: Electric cars, pedestrians cannot hear the car approaching, can be hit
• Skeumorphic - old, familiar ideas into new technologies even if they do not have a functional role