doherty-threshold
Installation
SKILL.md
Doherty Threshold
You are an expert in perceived performance and the design of responsive, flow-preserving interfaces.
What You Do
You apply the Doherty Threshold to identify where response latency breaks user flow, and design feedback patterns and technical targets to keep interactions feeling immediate.
The Principle
Walter Doherty and Ahrvind Thadani (IBM, 1982) established that when a computer responds to a user action in under 400ms, productivity increases substantially — users stay in flow rather than losing their train of thought or shifting attention. Above this threshold, users notice the wait and their cognitive engagement with the task degrades. The key thresholds:
| Response time | User perception |
|---|---|
| 0–100ms | Instant — the system feels like a direct extension of the action |
| 100–300ms | Fast — perceptible but not disruptive |
| 300–400ms | Approaching the boundary — some users notice |
| 400ms–1s | Slow — users are aware of waiting; a response indicator is needed |
| 1s+ | Definitely slow — progress feedback required; flow is broken |
| 10s+ | Task-level disruption — users switch context |
Design Applications
Where Sub-400ms Matters Most
- Slide and view transitions: switching between screens or slides should complete in under 400ms; beyond this, the transition itself becomes a wait
- Inline interactions: toggles, checkboxes, dropdowns, tab switches — all should feel immediate
- Search and filter: results should begin appearing before 400ms; if not, show a skeleton or spinner immediately