Psychology of usability

User interfacesJaana Holvikivi

EVTEK

Usability goals

International Standards Organization ISO 9241 definition:

Usability is the effectiveness, efficiency, and satisfaction with which users can achieve tasks in a particular environment of a product. High usability means a system is easy to learn and remember; efficient, visually pleasing and fun to use; and quick to recover from errors.

Effectiveness: can users successfully achieve their objectives?

efficiency: how much effort and resource is expended in achieving those objectives?

satisfaction: was the experience satisfactory?

Universal usability

Variations in physical abilities, disabilities Variations in use environment Diverse cognitive abilities Diverse perceptual abilities (vision,

hearing) Personality differences Cultural and international diversity Special user groups: children and the

elderly

Related fields

Engineering psychology Ergonomics Experience design Human-centered computing Human computer interaction (HCI) Industrial Design Systems engineering Ubiquitous computing User-centered design User experience design

Ease to learn in interface design

Familiarity in interface Observations and patterns

regular shapes proximity continuity recognition grouping

Logical structure

Grouping

1. features- colors, size, shape

2. prototypes, schemas3. internal consistency & similarity

in a group4. logical, conform with reality5. sparse (not too many categories)

Regular shapes

vision / perceptions simplifies and groups things together 5 circles (not 9 parts)

Proximity

Similarity

Continuity

Familarity

Connectedness

Object - background

Balance

size color

dark colors heavy position

proximity

do these move?

Creating forms

Left-aligned Vertical alignment of texts Items that repeat in the same

position Chunking & grouping Regular size input fields

Grid for forms

Code:

Name:

12345 OK

Address:

A Company

Old countryroad

Esbo02650

Efficient dialogue

6..15 groups

neat layout use of space experienced user prefer dense

forms novices prefer less crowded boxes

Fastest spotting of items

Mediocre spotting of items

Human perception: sees patterns

People can discriminate color and lighting

Object and background Borders and continuity Shapes and interpretations People remember even large chunks Football teams: colored shirts

Shades

source of light concave and convex

Interpretation

Interpretation

Müller-Lyer -illusion

Background

Colors

Help in recognition Have emotional values and

symbolic meanings - warning Warmth Color blindness common

Background

Human cognitive capacity 1

Based on patterns and schemas Chess masters remember nearly all

pieces in a game Affordances: visual object is

perceived through intended action; perception depends on context

Auditive and visual input separate

Human cognitive capacity 2

Attention: selective perception Object and background: discrimination,

exceptional features Attention is directed to one object Memory registers also unconscious

perception Automatic actions (bicycle riding) do not

need attention; but then action becomes fixed, difficult to modify (changes in interface)

Mechanicalsenses: touch,

painBody state (hunger,

vestibular sensation, etc.)

Brain

Audition

Vision

Chemical senses:Smell, Taste

Stored experience:MemoryEmotions

Movement

Action

Working memory

Modalities: perception

MEMORY

Short term memoryLong term or Reference memory

Modalities

Precedural memoryDeclarativememory

Sensorymemory

Workingmemory

Centralexecutive

Motorskills

Perceptuallearning

ConditioningSemanticmemory

Episodicmemory

Habituation and sensitation

RecallRecognition