# Interaction & Motion Design

**Track:** Systems, Strategy & Frontier — Design & Human-Centered Design — proposed (25)
**Framework / surface:** design
**Level:** Advanced
**Prerequisites:** Affordances, Signifiers & Feedback, Prototype: Fidelity & Making Tangible

**In one line:** Behavior over time — microinteractions, feedback, and motion as a functional material.

## Theory, aesthetics & inspiration

Interaction design is the design of behavior, not just appearance — Bill Moggridge and Bill Verplank, who coined the term in the mid-1980s, framed it as choreographing how a product responds over time. Alan Cooper's "About Face" (1995) grounded that behavior in users' goals rather than features, and Dan Saffer's "Microinteractions" (2013) showed that a single trigger-and-feedback loop — a toggle, a pull-to-refresh — carries a product's character. Motion is the functional material here: easing curves give weight and causality, signaling feedback, continuity, and meaning rather than decoration. Contemporary practice tempers this with the CSS prefers-reduced-motion query, treating motion as an accessibility contract, not an indulgence.

## References

- [Interaction design](https://en.wikipedia.org/wiki/Interaction_design)
- [Media Queries Level 5 — prefers-reduced-motion (W3C)](https://www.w3.org/TR/mediaqueries-5/)
- [The Role of Animation and Motion in UX (Nielsen Norman Group)](https://www.nngroup.com/articles/animation-purpose-ux/)