I am trying to figure out additional variables for classical conditioning. The example I am writing about is the response to being pulled over by a...

I am trying to figure out additional variables for classical conditioning. The example I am writing about is the response to being pulled over by a cop for speeding. I already have the Unconditioned stimuli/response and the conditioned stimuli/response. I am having a hard time find an example of an additional variable that makes sense with that example. The variables are Blocking