Amnesia is a very interesting phenomenon, which tends to be presented in various forms in movies as well as TV shows. Amnesia is split into two major types, retrograde - the inability to remember past events - and anterograde - the inability to create new memories. While both are shown in popular culture, there are some interesting instances of anterograde in terms of short term memory loss. Some examples include Lucy and Ten Second Tom in 50 First Dates
Both of these examples show signs of short term explicit memory loss, but at the same time, all three of them showed signs of their implicit memory still being intact. Explicit memory is that which we make a conscious effort to remember, such as events in our lives and facts. On the other hand, our implicit memory is automatic and includes muscle memory and can also be probed using priming.
Lucy had a fictional type of amnesia, called "Goldfield Syndrome, in which she was stuck in the same day due to damage to her hippocampus during a car accident the year before. Every day, she would wake up thinking it was her dad's birthday. When she went to bed, all the events of the day would be forgotten. While she would events of the day, she still remembered some events without trying. For example, she told Henry that she didn't know who he was, but she remembered dreaming about him every night. This shows that her unconscious still recognizes him but explicit memories, such as the dates that they went on were never encoded in her long term memory.
In the case of Ten Second Tom, the character was based on Clive Wearing. Tom would converse with a person, forget all about it in ten seconds, and then reintroduce himself. In this case, the explicit memories are clearly lost, as he cannot remember events that happened ten seconds ago; yet muscle memories such as waving and shaking hands when introducing oneself, still exist.
Here's a clip of Tom in the movie: http://www.youtube.com/watch?v=Jk7WuvNKe_g