The movie 'Memento' explores the connection between memory and one's self-identity. The movie gets its name from tattoos and Polaroid photos. When the main protagonist, Leonard Shelby suffers a head injury during an assault, he loses the ability to form new memories and uses these two mementos to remember the present.

The deliberate back - and - forth in time scenes, alternatively in color and black-and-white, confuse the audience as much as Leonard is confused as the continuity of his memories is lost. 

In the above attack, Leonard's wife is presumably killed, and the movie is all about his past identity (before the attack), and his present identity (after the attack) in which his aim is to find his wife's killer and take revenge by killing him despite suffering from brain damage that precludes him from forming new memories.

Leonard very aptly describes his condition to a motel attendant, "I have this condition; it is my memory; I have no short-term memory.I know who I am, I know all about myself.It is just, since my injury, I can't make new memories-every thing fades."One can feel Leonard's frustration and helpless rage as he tries to cope with his condition. 

This makes us ponder deeply on how important continuity of memory is in making us who we are and forming our identity. John Locke (1632-1704), also propounds the same theory that consciousness is key to self and continuity of consciousness plays an important role in the identity of a person. As per Locke, I am the same person as I was 10 years back as I have memories of what I did when I was 8 years old. Similarly, after waking from a night's sleep, I am the same person in the morning because I have a conscious memory of myself before I had gone to sleep the night before. Thus, I am morally responsible for my past actions.

On the contrary, Leonard has a short-term memory and has to store every new memory as mementos. He does not remember what he did a few minutes ago. Teddy says to him,"You don't even know who you are. "Leonard's past memory is till the attack in which his wife was killed, and that is why vengeance is so important to him. But if Leonard's existing memories of his life up until the injury are removed, then, who-is-Leonard?

Thus, in John Locke's view, the 'present memory' Leonard is not responsible for the killings that he does in the movie, as he would not have been the same person as the actual 'past memory' Leonard. He does not have any conscious memory of the murders he commits. There is no conscious continuity in his mind.

Continuity of memory makes up our 'self' or 'who we are.' However, sometimes our consciousness or memories deceive us; or maybe sometimes we deceive ourselves by choosing to forget or manipulate our memories of the past. I do remember many things from when I was 8, and I also do not remember so many incidents of that time that my parents relate to me. Thus I cannot be held responsible for many of those actions, even though I am the same person as that child of 8. In the movie, at the end, Teddy tells Leonard the 'truth' about the attack on him and his wife's'death. But is that what actually happened? 

Memento is thus a very complex and intriguing film but it does vindicate Locke's theory that one's consciousness is one's identity. If the memory of the act is not there, then that person is not responsible for the act. Without continuity of memory, one's self-identity cannot be maintained.