If someone were to say to you “say alligator” and you responded with “crocodile,” this would be an example of thematic control because there would be no point-to-point correspondence between the stimulus and the response. For that matter, you could say “doorknob” and that would be thematic control, too.
When a controlling variable evokes a response and has the following features:
There is NO point-to-point correspondence between the controlling variable and the response
Whether or not there is formal similarity between the controlling variable and the response
Formal characteristics of either the controlling variable or the response
Dynamic characteristics of either the controlling variable or the response