Concepts · Domain B
Discriminative stimulus (Sᴰ) vs. motivating operation (MO)
The difference in short
The discriminative stimulus (Sᴰ) and the motivating operation (MO) are different antecedents. The MO changes the value of a reinforcer and also the current frequency of the behaviors that have produced it. The Sᴰ signals that the reinforcer is available if a response occurs. Quick rule: MO = wanting; Sᴰ = knowing it's available.
Quick comparison
| Motivating operation (MO) | Discriminative stimulus (Sᴰ) | |
|---|---|---|
| Operation | Alters the value of a reinforcer | Signals the reinforcer is available |
| Effect | Changes the reinforcer's value and the current frequency of behaviors that have produced it | ↑ Behavior is more likely |
| Example | You haven't eaten in hours → food is worth more now. | You see the restaurant is open → you go in to order. |
How to tell them apart
- Does the antecedent change how much you WANT the reinforcer (MO) or signal that it's AVAILABLE (Sᴰ)?
Examples
MOMotivating operation
You haven't eaten in hours → food is worth more now.
SᴰDiscriminative stimulus
You see the restaurant is open → you go in to order.
Frequently asked
How do I quickly tell MO from Sᴰ?
The MO affects the reinforcer's value (being hungry); the Sᴰ signals that it's available (seeing an open café). Wanting vs. knowing it's available.
Related concepts
Practice discrimination, not just definitions
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