If there was not an already fairly strong tendency to say “python,” the stimulus “Monty” could just as well evoke other responses, such as “Hall” or “that’s not his name,” or whatever.
A type of controlling variable with the following features:
It sums with another controlling variable to evoke a response in a case of multiple controlling variables
The supplemental variable, by itself, is never likely to be sufficient to evoke the response
The type of controlling variable