Attention

4 main types.

1. Selective: Tuning out other things to a select set of stimuli
2. Sustained attention: Focusing on a single task for a long time
3. Divided attention: Focusing on multiple tasks at once
4. Executive attention: More organised sustained attention - having a plan/end goal in mind and tracking progress over a long term task

Focus determines how a system is interacted with, so grabbing attention in the right ways makes for effective interfaces.
How to keep attention:

• Don’t clog the UI
• Switch visuals often to keep it fresh
• Make tasks intuitive, so less focus effort is needed to complete a task
• Don’t overdo attention grabbing techniques, it can be annoying

Memory

Short term memory

• Can hold ~4 things at a time
• Used as a scratchpad for holding transitory information

Long term memory

• Episodic: Events and experiences in sequential, serial form. How we remember / reconstruct past events.
• Semantic: Collection of facts, concepts and skills, which are derived form episodic memory.

Commiting to long term memory

• We need to make committing interface actions to long-term memory as effortless as possible.
• Common design patterns can help: eg. people already know that blue text = hyperlink, exploit that pattern

Norman’s human action cycle

• Gulf of evaluation: Psychological gap of interpreting a UI, and the expected result of performing an action.
• Gulf of execution: Gap between the user’s goals and the means to execute them, ie. number of steps required to do something.

We can extract some design principles to optimise these aspects of a design.

• Visibility: Users can tell the system’s current state and their possible options
• Good conceptual model: Action outcomes are consistent in their presentation
• Good mappings: Easy to determine an action’s outcome from it’s appearance and context
• Provide feedback: Users get constant and consistent feedback on the effect of their actions

Gestalt laws of perceptual organisation

1. Figure-ground principle: People segment vision into a “figure” (foreground) and “ground” (background)
2. Similarity principle: form informs function (eg. blue hyperlinks)
3. Proximity: Elements close to eachother have similar function
4. Common region: Elements grouped together (eg. in boxes) have similar function
5. Continuity: Objects on a line/curve ae continuous and similar
6. Closure: Complex arranements are seen as a single pattern (eg. tiger image made of black stripes)
7. Focal point principle: Attention is drawn to a standout element

Affordances and signifiers

• Affordances: Functions an object allows us to do
• Signifiers: Cues/hints as to an object’s affordances For example, a road has the affordance of being able to walk on it, but crossings act as a signifier as to where you should cross.
  A save icon is a common signifier, informing a user of the save button’s affordances.

Usability

Concepts that impact system design:

• Feedback: Informing users of the effects of their actions
• Constraint: eg. blurring non-focused activities
• Mapping: Relate controls to their effects eg. dragging objects into a recycle bin
• Consistency: Similar operations for similar elements for similar tasks

Nielsen’s usability principles:

1. Visibility of system status
2. Match system and real world: ie. use familiar language to user
3. User control and freedom: Give escape routes such as an undo button
4. Consistency and standards (especially consistency in the use of language)
5. Help user recognise and recover from error
6. Error prevention: eg. “Are you sure?” dialogue
7. Recognition, not recall of action flows
8. Flexibility and efficiency of use: eg. macros for advanced users
9. Aesthetic and minimalist design
10. Provide help and documentation

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