S-delta
A stimulus in whose presence a particular response has not been reinforced, so that response becomes less likely when the stimulus is present (written SΔ).
An S-delta (SΔ) is the counterpart of a discriminative stimulus. Responses made in its presence have not produced reinforcement, so over time the learner stops making that response when the S-delta is present. A vending machine with an "out of order" sign is an S-delta for putting in money, and a closed sign on a store is an S-delta for trying the door.
In discrimination training, the stimuli that are not the target function as S-deltas for that response. If the instruction is "Touch spoon," the cup and plate in the array are S-deltas for touching: touching them is not reinforced. Whether something is an SD or an S-delta depends on the response and the reinforcement history, not on the object itself. The cup is an S-delta for "Touch spoon" and an SD on trials where the instruction is "Touch cup."
An S-delta is not a punisher and does not mean the learner will be reprimanded. It only signals that the particular response will not be reinforced at that time.
For an RBT, delivering reinforcement consistently only in the presence of the SD, and not in the presence of S-deltas, is what makes discrimination training work. Accidentally reinforcing an incorrect choice weakens the discrimination.
Example and non-example
| Example | During a matching program, the RBT reinforces placing the card on the matching picture. The two non-matching pictures are S-deltas for placing the card there, and placements on them are not reinforced. |
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| Non-example | Talking out of turn has been reprimanded whenever a particular teacher is present, so that teacher's presence signals that the response will be punished. That makes the teacher a discriminative stimulus for punishment; an S-delta signals only that reinforcement is not available. |
Don't confuse it with
| Discriminative stimulus | Responses in the presence of an SD have been reinforced; responses in the presence of an S-delta have not. |
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| Extinction | Extinction is the procedure of no longer reinforcing a response; an S-delta is a stimulus that signals that the response is not reinforced in its presence. |
Test yourself
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Question 1In discrete-trial teaching, what is a discriminative stimulus (SD)?
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B: A stimulus that signals reinforcement is available for a response. An SD is a stimulus in whose presence a response has been reinforced, so the response is more likely when it is present. In DTT the SD is usually the instruction together with the materials.
- A: That describes an S-delta, not an SD.
- C: Extra help is a prompt; the SD is the instruction or cue itself.
- D: That describes a reinforcer, which follows the response.
Task C.3 · 40-hour curriculum section E
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Question 2What does discrimination training involve?
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B: Reinforcing a response when one stimulus is present and not when other stimuli are present. Discrimination training is differential reinforcement across stimuli: the response is reinforced when the SD is present and not reinforced (extinction) when an S-delta is present. Over time the response occurs mainly in the presence of the SD.
- A: That describes shaping, which changes the form of a response rather than which stimuli it occurs in the presence of.
- C: That describes forward chaining, which links steps of a behavior chain.
- D: That describes programming for generalization, which spreads a response to new stimuli instead of narrowing which stimuli control it.
Task C.6 · 40-hour curriculum section E
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Question 3In discrimination training, an S-delta (SΔ) is a stimulus in whose presence:
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D: a response has not been reinforced. An S-delta is a stimulus in whose presence a given response has not been reinforced. Because responding does not pay off when it is present, the response becomes less likely in its presence.
- A: That defines a discriminative stimulus (SD), the stimulus that signals reinforcement is available.
- B: A prompt is added help from the teacher; an S-delta signals that reinforcement is not available.
- C: That describes an establishing operation, a kind of motivating operation, not an S-delta.
Task C.6 · 40-hour curriculum section E
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On the RBT exam
This term belongs to task C.6 Discrimination training in content area C, Behavior Acquisition, which is 19 of the 75 scored questions.