In Jurassic Park, a character diverts a dinosaur’s attention by throwing a flare away from him. The dinosaur chases the flare while they escape. Later, Jeff Goldblum does the same and the dinosaur ignores the flare.
We could have just been shown the Jeff Goldblum event. However, it had a stronger impact because we were shown the earlier success.
A similar scene exists in Close Encounters of the Third Kind. Dreyfuss is stopped in the middle of the road looking up directions at night. Another vehicle comes up behind him - we see only the headlights. Dreyfuss waves it on. This happens again some minutes later, and he does the same. But this time, the lights rise vertically. It has a bigger impact on the audience because they have seen the scene just recently (even if they do not remember it).