If I ask you to think of times that you were assertive, and there's music playing in the background and I tell you that this music makes it easy to remember times that you were assertive, then you won't use your feeling of easiness as a source of information in your judgment. Instead of using the feeling (which would make your assertiveness rating go down with the number of examples, because it would seem harder to think of them), you use the amount of examples (which makes your assertiveness rating go up with the number of examples). The main point of the third experiment is to show that there are conditions under which both interpretations of the availability heuristic are valid. Sometimes we use feelings of ease and difficulty, sometimes we use mental content.

Does that make sense?