Jamie heard about a divorce that was published in the RAG MAG, which she does not believe is very reliable. However, over time, she forgot where she heard about the divorce. The fact that she later came to believe the story was true is known as .

The sleeper effect.

Explanation:

As the exercise presents, Jamie heard about a divorce that was published in the RAG MAG, which she does not believe is very reliable. However, over time, she forgot where she heard about the divorce. The fact that she later came to believe the story was true is known as the sleeper effect. The sleeper effect is, as suggested, a psychological phenomenon that relates to persuasion. It is a delayed increase of the effect of a message that is accompanied by a discounting cue. So, in this case, Jamie heard statement X from place A. After some time, she forgot where she had heard it, but the information (statement X) remained in her mind.