Ease of Use Design with Cognition
PERCEPTION
How does human perception affect the way users interact with interfaces?
MEMORY
Short-term and long-term memory in interface interaction
LIMITATIONS
Limitations and their implications for interface design
LEARNING
How users learn to use interfaces
Perceptions
We perceive what we expect
- Design rules based on human psychology
- How we perceive, learn, reason, remember and how we convert intentions into actions
- Use human cognition
- Perceptual & cognitive psychology
- User-interface design guidelines are based on human psychology
- We largely perceive what we expect to perceive
- Our expectations, therefore our perceptions, are biased by
- the past our experience
- the present the current context
- the future our goals
Perceptions – biased by experience
- Users select items without looking at them carefully
- Example of a design guideline: place controls consistently
Perceptions – biased by current context
- Meanings dependent on the surrounding words (context window)
- Polish silverware – Fold napkins
- Polish silverware – French napkins
Perceptions – biased between senses
- What we see is biased by what we hear
- What we hear is biased by what we touch
- Recognition is stimulated by the context
- This includes:
- nearby objects
- events
- memories
- e.g. dog chases a cat after a car journey
Bias by Goals
- Things unrelated to our goal get filtered out
- For example: websites we don’t ignore items we don’t notice them.
- Analogy: at a party we pay attention to a person/persons and filter out the ‘noise’.
Design Implications
- Avoid ambiguity
- Rely on conventions and standards
- Upper left light on buttons
- Be consistent
- Place items in consistent locations
- Same color, font style etc.
- Understand the user’s goals
Gestalt principles of visual perception
- Early 20th century German psychologists researched how humans visual perceptions work
- We impose structure on what we see
- We perceive
- whole shapes, figures and objects
- rather than disconnected edges, lines and areas
- The German word for shape is ‘Gestalt’ so these theories became known as the ‘Gestalt principles of visual perception’.
- Proximity
- Similarity
- Continuity
- Closure
- Symmetry
- Figure / ground
- Common face
Proximity
- Objects near each other appear grouped
- Example: stars are horizontal or vertically grouped
- Design objects together
- To reduce visual clutter group without boxes or borders
Similarity
- Objects that appear similar also appear grouped
Continuity
- We tend to resolve ambiguity
- Fill in missing data
- Perceive whole objects
- Assume continuous forms
Closure
- Similarly to continuity
- we close open figures
GUI use – we stack objects
Symmetry
- We can exploit this trait in design
- 3D on a 2D display
Figure / Ground
- We separate into foreground and background
- Foreground is primary attention
Common Face
- Moving objects
- We perceive objects that are moving together as grouped or related
- Work together not individually
Seek visual structure
We seek and use visual structure
- Perceiving structure helps us make sense of objects and events quickly
- So when information is presented in a structured way it is easier to scan and understand
- People read top to bottom so labels below are poor design
- Also poor design is if labels are as close to unrelated information as they are to the related information.
Long numbers
- Small pieces of information can be made easier by applying structure
- separate fields
- spaces or punctuation
- 4151234567 or (415) 123 – 4567
- 1234567890123456 or 1234 – 5678 – 9012 – 3456
- Dates can be formatted differently – Inform the user of the required format
Visual hierarchy
- An important method to provide information that is easy to understand is to use a visual hierarchy
- Break information into sections
- Label each section
- Sections & subsections form a hierarchy
- Higher sections are presented more prominently
- Users can find things quicker