CSE 463 - Midterm

Design of Everyday Things

Don Norman
- focus on the interplay between people and technology

Usability Analysis

deals with 5 components
- Easy to learn
- Efficient to use
- Easy to remember
- Few errors
- Subjectively Pleasing

usability: Focus on tasks

- Focus on completing a task
- people have goals when interacting with systems
different users might have different goals
Example goals: purchase a flight ticket for two people, warm up food, send money to a friend

Gulf of Evaluation

- concerned with deciding whether actions were successful
- Feedback: "does the system provide a physical representation that can be directly perceived and that it is directly interpretable in terms of intentions and expectations of the person

Emotional Design

Emotional connections with products at three levels:
- Visceral: first reaction, perceived quality from look and feel
- Behavioral: experience-based, assessment of product's performance
- Reflective: reasoning, reflect on the product's impact on our lives

Validating Task

- find a target user
- revise task examples or discard them

Discovering requirements: why

a req is a functionality or a quality that the product must have
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Human-centered design (HCD)

an approach that puts human needs, capabilities, and behavior first, then designs to accommodate those needs, capabilities, and ways of behaving

HCD is concerned with the design of the

System functionalities and interaction sequence

Human Centered Design Process

Takes place within the DDDD (Discover, Define, Develop, Deliver) model. The process starts with Observation, then Ideation (idea generating), then Prototyping, then Testing solutions to problems. This process is iterative.

Common Mistakes in System Design

• Ego-centric fallacy: Other people think and feel like me (the designer).
• People will read the manual. • More functionality is better.
• People are completely logical.
• People do not make mistakes.
• Only considering ideal use and context.

Signs of good design

- know who are the real users
- fit human capabilities and context
- easy to discover and understand basic operations without reading a manual
- let people recover from errors

Fitt's Law

- Model of human psychomotor behavior
- the time required to point a target is a function of the distance to the target and the width of the target

Easy to Learn

- focus on new users
- ideally learn by exploration

Easy to Remember

- Occasional use
- how to measure: past user who has been away, longitudinal study, memory experiments

Efficient to use

- Efficient: low resources(e.g., time, mental load)
- Existing user on expert performance
- defining expertise
- how to measure? time complete a task

Subjectively Pleasing

- how to measure: user rating, observation metric
- Danger: user bias

Usability: Focus on Users

- who is the user of your system
- what knowledge and abilities they have
- what are their interests

Two gulfs

- gulf of execution
- gulf of evaluation

Gulf of Execution

- Translating goals into actions
- Discoverability: How do i know what i can do?
- does the system provide actions that correspond to the intentions of the user

Good design is "discoverable"

- Affordances
- Signifiers
- Mapping
- Feedback

Affordances

an object's design suggests how to interact with that object

Signifiers

Signs that make an affordance known to the ursers

Mapping

Spatial correspondence between the layout of the controls and the devices being controlled

Feedback

Communicating the results of an action (ex. walk sign button saying 'wait' or error pop up)

Physio-pleasure

A sensual pleasure that comes from touching, smelling, hearing or tasting something. It can also be derived from a feeling of satisfaction that comes from the effectiveness of an object in enabling an action to be performed

Socio-pleasure

Pleasures that come from a feeling of belonging to a social group, social-enablers, and other ways that one can identify oneself with social groups.

Psycho-pleasure

Types of pleasure that comes from cognition, discovery, knowledge and other things that satisfy the intellect.

Ideo-pleasure

Pleasure derived from satisfying people's tastes, values and aspirations.

accessibility

removing the barriers that would otherwise exclude some people from using the system at all

accessibility barrier: Physical/physiological

- non-ergonomic design
- not considering different types of processing information

accessibility barriers: Conceptual

- Non-understandable systems
- not considering young and older users

accessibility barriers: Economical

Designing expensive products

accessibility barriers: Cultural

Making normative assumptions about cultural aspects

accessibility barriers: Social

Making normative assumptions on social contexts

how to make something more accessible

- Using Colors
- Double-code information
- Include images and media alternatives
- Don's assume people use mouse

human abilities

- Perception
- Cognition
- Motor Control
- Needs
- Experience
- Communication
- Collaboration

Perception

- processing of the interactive system through our five senses
- visual perception is dominant in desktop and mobile interfaces
- visual design guidelines based on experimental psychology

Gestalt Principles (GP)

Principles that describe the brain's organization of sensory information into meaningful units and patterns. The seven Laws are widely applied in many design domains.

(GP) Proximity

Objects near each other (relative to others) appear grouped, while those farther apart do not

(GP) Similarity

Similar-looking objects appear grouped, all other things being equals

(GP) Continuity

When visual elements are aligned with each other, we perceive them as continuous forms rather than disconnected segments

(GP) Closure

the tendency to complete figures that are incomplete

(GP) Symmetry

automatically organizes and interprets the data to simplify it and give is symmetry, making it easier to comprehends

(GP) Figure/Background

- Our mind separates the visual field into the figure (the foreground)
and ground (the background)

(GP) Common Fate

Objects that move together are perceived as grouped or related

Visual Hierarchy

- Users deduce the information structure of a system from its design
- Most important content should stand out the most
- Design hierarchical relationships among elements
- Visual hierarchy must reflect information hierarchy

Attention and Memory

- sensory (touch, small, hear, ...)
- short-term
- Long-term

Attention

- selectin things to concentrate on at a point in time from the mass stimuli around us
- information should be structured to guide users attention

Change Blindness

failing to notice changes in the environment

Memory: short term

- it decays rapidly
- has limited capacity: 7+-2 items, actually 4+-1
- chunking and meaning of information can lead to an increase in capacity

Memory: long term

- Deletion is caused by decay and interference
- Information retrieval: recognition and recall

Recall is harder than Recognition

- Recognition is about patter matching

- Recall is the process by which individuals search in their memory to find a piece of inromation

Descriptive vs. Predictive Models

Descriptive model: analogy, metaphor, categories, design spaces

Predictive Models: Analytic Statistics, equations

Fitt's Law of Movement Time (mt)

MT ~ D/W
D = distance to the object
W = Width of the object


a+b = Device dependent
Log2(D/W +1) = Index of Difficulty

MT = a+b * Log2(D/W + 1)

Impact of input Device

touchpad = 1.6
Trackball = 2.9
Joystick = 5
Mouse = 10.4
Hand = 10.6
eye tracker = 13.7

Steering Law

Governs the time it takes to steer a screen pointer along a constrained path to a target; the wider the path, the faster you can move the pointer to the target.

Derived from Fitts' law

Limitations of Fitts' and Steering Laws

- Time to find a target
- Visual saliency or content of the target
- muscle memory

Keystroke Level Model

Models performance given a sequence of steps for an expert user

power law of practice

- if you repeat a task, you'll get faster at it
- Applies to typing

Tn = T1 n^-a

PACT

- User-centric framework for thinking about design problems
P: who are the users?
A: how does the interaction occur?
C: where the interaction is taking place?
T: What technologies are used?

PACT: People

How do users differ?
Primary: frequent hands-on
Secondary: occasional or via someone else
Tertiary: affected by its introduction, or influence of its purchase

PACT: Activities

How does the interaction occur?
- what is the overall purpose of the activity
- temporal aspect: regular or infrequent
- Cooperation: one or more actors
- Complexity: well-defined or vague
- safety critical: can result in injury
- Impact of error: what kinds of errors

PACT: Context

Where does the interaction occur?
Physical context: noise, light, time
Social context: alone or with others
Organizational Context: related services or businesses

PACT: Technology

What are the technology requirements for the task?
Input
output
communication
content

Common Mistakes in PACT

- Considering only on a subset of users
- not specifying various parameters of the activities and context
- Proposing a technology instead of analyzing the variety of relevant technologies and tech req

Research Methods

- open ended interview
- contextual inquiry
- Observation ethnography
- Surveys Diaries
- Log file analysis
- analysis of archival data

Question to avoid when interviewing

- long questions
- Compound sentences
- Jargon and Language that the interviewee may not understand
- leading question that make assumptions
- unconscious biases, gender stereotypes

Contextual Inquiry: Four Main Principles

• Context: Going to the user, wherever they are, and seeing what they do as they do it
• Partnership: User and interviewer explore user's life together
• Interpretation: Observations interpreted by user and interviewer together
• Focus: Project focus to understand to what should be paid attention

Affinity Diagram

- record all notes or observations on individual card or sticky notes
- look for patterns and notes or observations that are related
- create a group for each pattern or theme
- Give each theme or group a name

Steps for developing task descriptions

- describes what the user wants to do but does not say how the user would do it
- very specific
- describes a complete job from when the user starts until they achieve their goal
- says who the users are (fred)
- as a set, the task descriptions identify a broad coverage of users and task types

Personas

bring users to life
- good personnel help the designer with design decisions and remind the team about

Why?
- easy way to communicate with others
- Helps with design

Persona should have

photo
age
demographic info
maybe a quote
primary goals
motivations
pain points
behaviors, daily routine

Scenarios

Informal narrative description reports about user tasks

Task Descriptions vs. Scenarios

Scenarios
- can involve description of tech
- used in wider range of situations

Conceptual model

A high-level description of how a system is organized and operates

Implementation model

describes what the system does
1. documentation
2. interface and behaviors

User's Model = Mental Model

Describes how user think about the system

Horizontal Prototype

- give a broad view of the system
-showing how the functionalities are brought together

Vertical prototype

- Elaborate on specific features or functions
- Demonstrate that the requirements are technically possible

Evaluation: Why?

- Conceptual design: do users understand the conceptual model?
- Prototyping: evaluate alternatives
- After Deployment: Collect users' requirements for future redesigns, privide usability assessments