There is also a thematic relationship between “spider” and “suspend.” However, “spider” is not a main thematic source because the other responses that it might control — such as “web,” “spin,” and “insect” — would all have a very different effect upon the listener than “suspend.” We call this a secondary thematic source.
A situation with the following features:
It controls a large group of responses
All of the responses would have about the same effect on a listener
Type of thematic elementary relationship (e.g., mand, tact, intraverbal)
Specific features of the stimulus and response
What will the spider do,
suspend its operations