Perpetual intermediates

Most people are perepetually intermediate - only few beginners and experts

Design should target intermediates!

Interaction Design

• The design of spaces for human communication and interaction. (Winograd, 1997)
• Designing interactive products to support the way people communicate and interact in their everyday and working lives. (Sharp, Rogers and Preece, 2011)

Design Thinking (Visual Thinking)

To understand them, the systems had to be constructed, and their behaviour observed. (Herbert A. Simon, 1969)

We need rapid prototyping and testing through observation!
However, this is just an opinion, and there are people who think otherwise.

• Design research is great for improving existing product categories, but essentially useless for new, innovative breakthroughs.
• Conceptual inventions happen because technology has finally made them possible.
• Technology first → Invention second → Needs last

Design-thinking process

• Empathize
• Define
• Ideate
• Prototype
• Test
• Implement

We might have to turn back, or lop multiple times!

Fundamental Design Principles

• Generalizable abstractions for thinking about different aspects of design
• The dos and don'ts of interaction design
• Key considerations in interface design: what to include and what to avoid

Affordance

Objects have both perceived and actual properties.
When an object's perceived and actual properties align, it has right affordances!
Well-designed objects can be used effortlessly - without words, symbols, or trial and error.

Ex) A chair affords sitting.

Different users have different affordances.

• Kids: need large buttons, simplified interfaces
• Elderly: reduced mobility, slower reactions
• Disabled: struggle with vision, mobility, and interaction limitations

Mapping

Controls should correspond logically to their effects.
Good/natural mapping make the relationship between controls and actions obvious.
Minimize the need for labels or legnends - users should instinctively know what to do without instructions.

Constraints

• Visible Constraints: limit the possible actions by appearance
• Physical Constraints: physical limitations constrain possible operations
• Semantic Constraints: depending on our meaning of situation
• Cultural Constraints: allowable actions for social situations (e.g. Is stop sign red or blue?)
• Logical Constraints: use spatial layout of components (only one piece left, only one possible place to go)s

Conceptual model

Mental model of how things work.
Mental models are formed by:

• Affordances: what an object suggests it can do
• Constraints: what limits an action
• Mappings: how controls correspond to effects
• Experience: what users have seen before
• Training & Instruction: learned behavior

But there are three aspects of mental models!!!

• Design model: how the designer envisions the system working.
• User's model: how the user believes the system works.
• System image: the actual system representation that the user interacts with.

Great design aligns three mental models! Bad design doesn't

Make things visible

Important functions should be immediately noticeable.
Functions don't have to be seen; e.g. it can be touched.

Feedback

Good design should provide user with clear visual, tactile, auditory feedback.
User need confirmation that their actions have been recognized.
Good feedback improves interaction and prevents user errors.

Causality

Be responsive - users need to recognize causality!

Perceptual fusion: people assume that the thing happens right after an action be caused by that action. (Feedback should be within 100ms!)
If the task takes too long, you need feedback such as hourglass.

Consistency

Similar elements for achieving similar tasks

Other Design Constraints

• Cost: real design has limited cost
• Space: real design has limited space
• Discoverability: if some controls are hidden, how do people find them?