Iterative design is a process that uses repeated cycles of prototyping, testing, analyzing, and refining to overcome problems caused by incomplete requirements.
A prototype is a primitive version of a system used to explore design ideas.
Causes
Inherent problems of incomplete or unclear requirements in early design stages.
Goals / Objectives
Overcome limitations of upfront specification by learning through building and testing.
Gather design knowledge through practical experimentation.
Importance
Enables early identification of design flaws.
Supports user involvement and feedback throughout development.
Benefits
Facilitates evaluation and feedback from stakeholders.
Helps team members communicate design ideas effectively.
Allows designers to test out ideas personally.
Supports comparison of alternative design solutions.
Procedures
Build a prototype (of varying fidelity).
Test it with users or stakeholders.
Use insights gained to refine or rebuild the design.
Repeat the cycle until the final system is developed.
Advantages & Disadvantages
Not specified in notes as a direct comparison for iterative design alone (covered under prototype types and fidelity levels).
Impact / Effect
Leads to more user-centered and functional final products.
Reduces risk of costly redesigns late in development.
Examples
Not specified in notes beyond general prototyping examples covered in other subtopics.
Throw-Away Prototyping
Definition
A prototype is built and tested for learning purposes, then discarded; the final product is built from scratch using insights gained.
Causes
Need to explore uncertain requirements or user needs without committing to early implementation.
Goals / Objectives
Gain design knowledge and user feedback quickly.
Inform the development of the final system without being constrained by prototype code or structure.
Importance
Useful when requirements are highly ambiguous or volatile.
Benefits
Encourages experimentation without concern for maintainability.
Reduces risk of building the wrong system by validating assumptions early.
Procedures
Build a quick, often low-fidelity prototype.
Test with users or stakeholders.
Extract design lessons.
Discard the prototype and build the final system based on insights.
Advantages & Disadvantages
Not explicitly listed in notes for this specific type, but implied under general prototyping trade-offs.
Impact / Effect
Final system benefits from early user feedback without inheriting prototype limitations.
Examples
Not specified in notes.
Incremental Prototyping
Definition
The final product is built as separate, independent components, each developed and released incrementally; prototypes represent parts of the future system and are later combined.
Causes
Large or complex systems that can be logically partitioned into modules.
Goals / Objectives
Deliver functional parts of the system early.
Allow users to interact with partial implementations while the full system is under development.
Importance
Enables phased delivery and continuous user engagement.
Benefits
Users receive usable functionality sooner.
Development risk is distributed across components.
Easier to manage and test individual parts.
Procedures
Create an overall system design.
Partition the system into smaller, independent components.
Build and release one component at a time as a prototype or partial product.
Combine all components into the final system over successive releases.
Advantages & Disadvantages
Not explicitly contrasted in notes, but implied as a structured alternative to throw-away or evolutionary approaches.
Impact / Effect
Results in a series of progressively more complete product versions.
Examples
Not specified in notes.
Evolutionary Prototyping
Definition
The prototype is not discarded; instead, it evolves through iterations into the final system.
Causes
When early user feedback and functional needs can be incorporated directly into a growing system.
Goals / Objectives
Start with a minimal working version and gradually enhance it based on user input and changing requirements.
Importance
Ideal for systems where core functionality is understood but details evolve with use.
Benefits
Continuous delivery of value.
Strong alignment with user needs through ongoing refinement.
Reduces rework since the prototype becomes the product.
Procedures
Begin with a limited but functional version of the system.
Release it to users.
Gather feedback and add/modify features.
Repeat until the system meets all requirements.
Advantages & Disadvantages
Not explicitly listed in notes for this type alone, but concept aligns with high-fidelity iterative development.
Impact / Effect
The system “grows” organically from a basic version to a mature product.
Examples
Not specified in notes.
Prototyping in HCI (Human-Computer Interaction)
Definition
A design technique where users interact with experimental, incomplete designs (prototypes) to test and refine interface ideas.
Causes
Need to evaluate usability, workflow, and interaction before full development.
Goals / Objectives
Involve users early in design.
Test interface concepts quickly and inexpensively.
Answer specific design questions (e.g., “How big should the icon be?”).
Importance
Bridges the gap between abstract design and real user experience.
Critical for user-centered design practices.
Benefits
Stakeholders can see, hold, and interact with designs.
Supports team communication and idea validation.
Helps examine design structure and compare alternatives.
Procedures
Choose a prototyping method (hand-drawn, screen-based, functional, etc.).
Simulate interaction (e.g., designer acts as system in paper prototyping).
Observe user behavior and gather feedback.
Iterate based on findings.
Advantages & Disadvantages
Not specified in notes as a direct comparison for HCI prototyping specifically.
Impact / Effect
Leads to more intuitive and effective user interfaces.
Examples
Mockup videos simulating system behavior.
Hand-drawn prototypes with pencil “clicks.”
Functional prototypes connected to real databases.
Types of Prototypes (by Fidelity and Form)
Definition
Prototypes vary in form and realism, from rough sketches to near-final interactive models.
Causes
Different stages of design require different levels of detail and realism.
Goals / Objectives
Match prototype fidelity to the current design question (e.g., layout vs. performance).
Balance speed of creation with depth of feedback.
Importance
Choosing the right prototype type ensures efficient use of time and resources.
Benefits
Low-fidelity: fast, cheap, flexible for early ideation.
High-fidelity: realistic, useful for usability testing and stakeholder buy-in.
Procedures
Hand-Drawn Prototype: Designer sketches screens on paper; user “interacts” with pencil; designer simulates system responses.
Tool-Drawn Prototype: Screens created digitally (e.g., MS Access, Visual Basic), printed, and used like hand-drawn versions.
Screen Prototype: Static screens shown on a computer; limited interactivity (e.g., simulated via secret keys or stickers).
Functional Prototype: Interactive elements work (e.g., open windows, update data, access real databases).
Advantages & Disadvantages
Covered under Low vs. High Fidelity comparison (see next subtopic).
Impact / Effect
Influences the type and quality of feedback received.
Affects team alignment and development direction.
Examples
Hand-drawn screens with pencil annotations.
Printed mockups from Visual Basic.
Clickable screens with yellow sticky-note responses.
Database-connected interactive demo.
Low-Fidelity Prototyping
Definition
Prototypes made with simple, non-digital materials (e.g., paper, cardboard) that do not closely resemble the final product.
Causes
Early design phase where speed and flexibility are prioritized over realism.
Goals / Objectives
Quickly explore and compare multiple design concepts.
Focus on structure, layout, and workflow—not visual details.
Importance
Enables rapid iteration and early user involvement without heavy investment.
Benefits
Less time and lower cost to create.
Effective for evaluating screen layouts and navigation concepts.
Serves as a useful communication tool among team members.
Encourages open feedback (users don’t mistake it for a finished product).
Procedures
Use sketching, storyboards, wireframes, index cards, or “Wizard of Oz” techniques.
Simulate interaction manually (e.g., designer plays the computer).
Iterate based on user comments or team critique.
Advantages & Disadvantages
Advantages:
Less time & lower cost
Evaluate multiple design concepts
Useful communication device
Addresses screen layout issues
Disadvantages:
Limited usefulness for usability tests
Navigational and flow limitations
Facilitator-driven (not user-driven)
Poor detailed specification
Impact / Effect
Supports early visualization of alternatives.
May miss usability issues that only emerge in interactive contexts.
Examples
Sketching: Quick hand-drawn UI ideas using simple symbols.
Storyboards: Series of sketches showing user task progression (from film industry).
Wireframes: Simple screen layouts with rectangles and annotations to show structure and flow.
Card-based prototyping: 3x5 inch index cards, each representing a screen (common in web dev).
‘Wizard of Oz’: Human simulates system behavior behind the scenes to mimic interactivity.
High-Fidelity Prototyping
Definition
Prototypes that closely resemble the final system in appearance and often in interactivity, though not always in full functionality.
Causes
Later design stages where detailed interaction, visual design, or performance must be tested.
Goals / Objectives
Validate look, feel, and behavior of near-final designs.
Collect accurate human performance data (e.g., task completion time).
Support marketing, sales, or stakeholder approval.
Importance
Provides realistic user experience for final validation before full development.
Benefits
Partial or complete functionality enables real interaction.
User-driven (not facilitator-dependent).
Clearly defines navigational schemes.
Useful for both exploration and formal testing.
Can serve as a marketing or sales tool.
Procedures
Built using professional tools (e.g., Adobe XD, Photoshop, Xcode/Swift, Web dev tools).
Includes interactive elements like clickable buttons, dynamic screens, and real data.
Tested with users in realistic scenarios.
Advantages & Disadvantages
Advantages:
Partial/complete functionality
Interactive
User-driven
Clearly defines navigational scheme
Use for exploration and test
Marketing and sales tool
Disadvantages:
Time-consuming to create
Inefficient for proof-of-concept designs
May blind users to major representational flaws (because it looks “real”)
Impact / Effect
Can lead to more accurate usability metrics.
Risk of over-investment in design directions that may still be flawed.
Examples
Interactive mockups in Adobe XD.
Functional iOS app demo built in Xcode.
Clickable web prototype with real navigation.
Prototyping Compromises (Horizontal vs. Vertical)
Definition
All prototypes involve trade-offs in scope and depth, typically categorized as horizontal or vertical.
Causes
Limited time, resources, or clarity about system requirements.
Goals / Objectives
Maximize learning within constraints by choosing the right compromise.
Importance
Understanding these trade-offs helps select the most appropriate prototyping strategy.
Benefits
Horizontal: broad overview of system scope.
Vertical: deep validation of specific features.
Procedures
Horizontal prototype: Implement many features at a shallow level (e.g., all menu items visible but non-functional).
Vertical prototype: Implement few features with full depth (e.g., one workflow fully functional from start to finish).
Advantages & Disadvantages
Not explicitly contrasted in notes, but described as two common compromise types.
Impact / Effect
Shapes the kind of feedback received (breadth vs. depth).
Examples
Not specified in notes.
Prototyping Tools
Definition
Software or physical kits used to create prototypes of varying fidelity.
Causes
Need for efficient, consistent, and shareable prototype creation.
Goals / Objectives
Accelerate design iteration.
Enable collaboration and user testing.
Importance
Tools determine the speed, fidelity, and interactivity achievable in prototyping.
Benefits
Digital tools allow easy sharing, versioning, and interactivity.
Paper kits support low-cost, hands-on ideation.
Procedures
Select tool based on fidelity needs and team skills.
Create screens, link interactions, and test with users.
Advantages & Disadvantages
Not explicitly compared in notes, but tools are listed with access models.