Jill's friends tell her they think she has a really good memory. She finds this interesting so she decides to purposefully test her memory. Jill receives a list of to-do tasks each day at work. Usually, she checks off each item as the day progresses, but this week, she is determined to memorize the to-do lists. On Monday, Jill is proud to find that she remembers 95 percent of the tasks without referring to the list. On Tuesday, her memory drops to 80 percent, and by Thursday, she is dismayed to see her performance has declined to 20 percent. Jill does not realize that she is demonstrating a natural mechanism of memory known as

proactive interference                    

Explanation:

In psychology, proactive interference is considered as one of the two different types of interference and is described as a phenomenon that occurs when an individual's old or former memories tends to interfere with his or her capability of encoding as well as retrieving a piece of new information.

According to various psychologists, it seems very difficult for an individual to create or develop a specific new memory that tends to contradict or oppose or is too similar as compared to the older memories.

According to the question above, Jill is demonstrating proactive interference.