Final answer:
The most likely explanation for Melissa's difficulty in remembering her new student ID number is proactive interference, where old information hinders the recall of newly learned information.
Step-by-step explanation:
A few weeks after Melissa's student ID number changed she had difficulty remembering it. When asked, she begins to recite her former student ID number and then has to correct herself. The most likely explanation for failing to remember the new student ID number is proactive interference. Proactive interference is a memory error that occurs when old information hinders the recall of newly learned information. In Melissa's case, her memory of the old student ID number interferes with her ability to recall the new one.
In contrast to proactive interference, if the new information had caused her to forget the old information, it would be an example of retroactive interference. It is important to note that this type of memory challenge does not relate to prospective memory, which is the aspect of memory that enables us to remember to perform actions in the future, nor to repression, which is a defense mechanism that blocks the conscious recall of anxiety-inducing thoughts or feelings.