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