Discriminative Stimulus
Also called: SD, S-Delta, stimulus control
Definition
A stimulus in the presence of which a particular response has been reinforced in the past, and which therefore comes to evoke that response. It signals the availability of reinforcement rather than altering its value. A stimulus correlated with the absence of reinforcement is called an S-delta.
In plain language
Something in the room that tells a person a behavior will work right now. A green light tells you that driving forward will go fine. It does not change how badly you want to get there.
Examples
A vending machine that is lit and stocked. Putting money in has paid off before when it looked like this, so a person does so again.
A learner asks for help only when a staff member is facing them, because requests made to someone turned away have not been answered.
Staff orientation signals whether the request will work.
Not discriminative stimulus
Several hours without a drink, which makes water more valuable. That changes how much the learner wants water, not whether asking will succeed.
A stimulus a learner has never encountered before, which cannot yet signal anything about reinforcement.
Commonly confused with
See also
Written from
- michael-1982 — Discriminative versus motivational functions
Written from Michael (1982), whose whole point is the distinction between discriminative and motivational functions. No textbook glossary consulted.
This entry has not yet been through clinical review. Treat it as a draft.