# Interaction Design (IxD)
Interaction Design (IxD) is the practice of designing interactive digital products, environments, systems, and services with a focus on behavior—how users interact with them. The term was coined by Bill Moggridge and Bill Verplank in the mid-1980s at IDEO, originally as "soft-face" design (later "interaction design"). While [[User Experience (UX)]] encompasses the entire user journey, interaction design specifically focuses on the moment-to-moment dialogue between user and product: actions, responses, feedback, and flows.
Interaction design draws on [[Cognitive Psychology]], [[Human-Computer Interaction (HCI)]], and [[Product Design]]. Key concerns include defining how products behave in response to user input, designing clear [[Affordance]]s and [[Signifier]]s, providing appropriate feedback, and creating coherent interaction patterns. The field has evolved from designing desktop software to encompassing mobile, voice, gesture, AR/VR, and conversational interfaces. Core texts include [[Don Norman]]'s *The Design of Everyday Things* and Alan Cooper's *About Face*.
## Interaction Design Focus
```
┌─────────────────────────────────────────────────────────────┐
│ INTERACTION DESIGN SCOPE │
├─────────────────────────────────────────────────────────────┤
│ │
│ USER INTERFACE SYSTEM │
│ │ │ │ │
│ │ ┌─────────────────────────────────────────┐ │ │
│ │ │ INTERACTION DESIGN FOCUS │ │ │
│ │ │ │ │ │
│ ├────▶ ACTION: User does something │ │ │
│ │ │ ↓ │ │ │
│ │ │ RESPONSE: System provides feedback ◀────┤ │
│ │ │ ↓ │ │ │
│ ◀────│ OUTCOME: User perceives result │ │ │
│ │ │ ↓ │ │ │
│ ├────▶ NEXT ACTION: Based on feedback │ │ │
│ │ │ │ │ │
│ │ └─────────────────────────────────────────┘ │ │
│ │ │ │
│ Goals Capabilities│
│ Context Constraints │
│ Abilities States │
│ │
└─────────────────────────────────────────────────────────────┘
```
## Five Dimensions of IxD
| Dimension | Description | Example |
|-----------|-------------|---------|
| **1D: Words** | Text, labels, microcopy | Button labels, error messages |
| **2D: Visual** | Images, typography, icons | Interface graphics |
| **3D: Physical** | Hardware, space | Mouse, touchscreen, keyboard |
| **4D: Time** | Animation, sound, duration | Loading indicators, transitions |
| **5D: Behavior** | How product responds | Feedback, state changes |
## Core Concepts
| Concept | Description |
|---------|-------------|
| **[[Affordance]]** | What actions are possible |
| **[[Signifier]]** | What communicates affordances |
| **Feedback** | Response to user actions |
| **Mapping** | Relationship between control and effect |
| **Constraints** | Limiting possible actions |
| **Consistency** | Predictable patterns |
| **Mental model** | User's understanding of system |
## Interaction Patterns
| Pattern | Use Case |
|---------|----------|
| **Direct manipulation** | Drag and drop, resize |
| **Menu selection** | Choosing from options |
| **Form fill-in** | Data entry |
| **Command line** | Expert text input |
| **Conversational** | Chatbots, voice assistants |
| **Gesture** | Touch, motion control |
| **WIMP** | Windows, Icons, Menus, Pointer |
## Design Process
| Phase | Activities |
|-------|------------|
| **Research** | User interviews, observation, analysis |
| **Define** | Personas, scenarios, requirements |
| **Ideate** | Sketching, wireframing, flow diagrams |
| **Prototype** | Interactive mockups, clickable prototypes |
| **Test** | Usability testing, iteration |
| **Implement** | Collaboration with development |
## Key Figures
| Person | Contribution |
|--------|--------------|
| Bill Moggridge | Coined "interaction design," IDEO founder |
| Bill Verplank | Interaction design framework |
| [[Don Norman]] | Cognitive design principles |
| Alan Cooper | Personas, *About Face* |
| Jef Raskin | Human interface design (Mac) |
| Dan Saffer | *Designing for Interaction* |
## IxD vs Related Fields
| Field | Focus |
|-------|-------|
| **Interaction Design** | Behavior, moment-to-moment dialogue |
| **[[User Experience (UX)]]** | Entire user journey, holistic |
| **UI Design** | Visual appearance, layout |
| **[[Product Design]]** | End-to-end product creation |
| **Service Design** | Cross-channel experiences |
| **[[Human-Computer Interaction (HCI)]]** | Research-focused |
## Interaction Modalities
| Modality | Input Method | Example |
|----------|--------------|---------|
| **GUI** | Mouse, touch | Desktop apps, mobile |
| **Voice** | Speech | Alexa, Siri |
| **Gesture** | Body movement | Kinect, Leap Motion |
| **Tangible** | Physical objects | IoT devices |
| **Gaze** | Eye tracking | VR interfaces |
| **Brain-computer** | Neural signals | Accessibility devices |
## Core Texts
| Book | Author | Focus |
|------|--------|-------|
| *The Design of Everyday Things* | [[Don Norman]] | Foundational principles |
| *About Face* | Alan Cooper | Comprehensive IxD methods |
| *Designing for Interaction* | Dan Saffer | Modern IxD practice |
| *Designing Interfaces* | Jenifer Tidwell | Pattern library |
| *Microinteractions* | Dan Saffer | Small moment design |
## References
- Moggridge, B. (2007). *Designing Interactions*
- Cooper, A. et al. (2014). *About Face: The Essentials of Interaction Design*
- https://en.wikipedia.org/wiki/Interaction_design
## Related
- [[User Experience (UX)]]
- [[Human-Computer Interaction (HCI)]]
- [[Product Design]]
- [[Affordance]]
- [[Signifier]]
- [[Don Norman]]
- [[Usability]]
- [[Design Patterns]]