Fixed Interval
FI
In Plain Language
The first response after a fixed period of time receives reinforcement.
ABA Definition
A schedule reinforcing the first specified response after a constant interval since the previous reinforcer.
Everyday Example
In a game, the first button press after a fixed cooldown collects a bonus.
ABA Example
In FI 2 minutes, the first target response after two minutes produces reinforcement.
How It May Be Used
Time passing alone does not deliver reinforcement; a response is required.