Scope
A control can function mechanically while producing uncertainty in use. The Ordinary Actuation Index records the conditions under which a person can initiate an action, recognize the response and stop thinking about the control itself.
Method
OAI observations consider tactile certainty, repeatability, response recognition, actuation force consistency, learned familiarity, expected feedback and ordinary-use confidence. Familiarity is treated as an engineering quality because a known response reduces unnecessary attention at the point of action.
| Observation | Meaning in field use |
|---|---|
| Tactile certainty | The control presents a distinct and repeatable point of actuation. |
| Response recognition | The resulting change can be recognized without a second confirmation channel. |
| Force consistency | Ordinary repetitions do not require materially different effort. |
| Learned familiarity | Repeated use reduces reasoning about the actuation itself. |
Button & Interface uses PCP availability language when a control’s access envelope is constrained by placement. Queue Technologies contributes approach and sequence observations where actuation occurs within managed waiting.
Revision history
Distinguished response from mere mechanical movement.
Added tactile certainty and force consistency.
Established learned familiarity as an ordinary-use consideration.
Aligned response certainty with SCR-6.
Related publications
Continue by concept
Printable web edition. A matching PDF is available: download OAI-98-22.pdf.