A final point is that the speaker can supply themself with the prompt or probe; it needn’t be another person. Notice that this makes the prompt situation more likely since often the speaker will be affected by the primary source.
A discriminative stimulus with the following features:
It is a supplementary stimulus
The person providing the supplementary stimulus can identify the response that the speaker is likely to emit
It is a supplementary stimulus
The person providing the supplementary stimulus cannot identify the response that the speaker is likely to emit
Whether the controlling relationship is formal or thematic
Who provides the supplementary stimulus (either another person or the speaker him or herself)