OK, so if the whole diabetes-Sammy story really happened to Leonard how does Leonard remember if it happened AFTER he developed the amnesia? How does Leonard even now he has the condition? How does he know that he suggested to the cops to find the guy who did it to his wife, and that they ignored him and never found the guy... if this all happened AFTER he got the amnesia? Shouldn't he always be waking up, dazed and confused, asking if his wife's OK, because last he remembers she was laying in a pool of blood?
That is the ORIGINAL impression you are given - that Leonard heard the story about Sammy before he got the injury. But the twist is that what happened to Sammy actually happened to Leonard himself - but it could have only happened to Leonard AFTER getting the condition (it's the whole point of the story.)
I think this may be the point of the "conditioning" thing he's talking about. It's possible that he wrote down the altered story and read it over and over again until it sort of stuck. This could also be the reason he keeps telling it to everyone. (Okay, this is a long shot, but it's all I got.)
This troper was under the impression that Leonard's condition was degenerative with his memory gradually worsening from the attack onwards, until he's completely incapable of forming new memories. It could also tie in with the issue (mentioned below) of the apparent variation in how long Leonard's short-term memory lasts: if the condition itself is degenerative, he could have occasional "peaks" or spikes in how long he's capable of remembering things.
It's all because of conditioning. After waking and finding out his wife had died for hundreds of days, it was finally cemented into his mind.
As far as I understand it, the Sammy stuff happened before. That is, when he was normal and an insurance investigator he met a man (who had no wife) named Sammy and learnt about Sammy's condition. But Sammy actually was just faking it. Then the assault happens and Leonard does the whole insulin thing. Then the trauma of seeing his wife's corpse like that, again and again with (this is speculation) the insulin needle present and knowing that insulin overdosing can cause a coma like happened, the trauma scrambled his already scrambled brain and lodged itself in places other than short term memory (the rest of his brain, like conditioning, still worked) so he couldn't remember what happened but parts of his subconscious could and the trauma caused him to project his guilt onto Sammy and give him the goal of killing his wifes "murderer" so that he could somehow put his wife's death right. The police memory was manufactured from this.
I just assumed it was a lie Teddy told him to keep him occupided long enough for his memory to fade so he would forget what just happened. Teddy had manipulated him for years.
I just finished my second viewing of the movie, and I noticed that Teddy specifically says that Lenny used the whole conditioning thing to alter his memory of certain things. This was at the very end of the movie while they're both yelling at each other, so it's understandable if people missed that line. I'm pretty sure I did the first time around. So after he got put in an institution, he basically blended his story and Sammy's so that he could feel blameless for his wife's death.
If Leonard has met Teddy before, how does he not have a picture of Teddy already? From what's been in the movie, there's no particular reason for Leonard to destroy previous photographs of Teddy, or anyone else, unless for some reason Leonard was dissatisfied with the previous kill in a way to destroying Teddy's photograph. Still, he hasn't destroyed any photographs except Jimmy Grants and the mysterious pointing picture, so it is quite out of place.
The way he destroys those two photos suggests to me that it's something he does regularly. He burns a photo when he decides he doesn't need that memory any more; otherwise he'd be carrying thousands of photos around with him. I guess Teddy knows this. After every kill: "Glad I could help you, Lenny. Goodbye forever." One burned photo later... "Mr Shelby? You don't know me, but I think I can help you find the guy who murdered your wife."
Also this has only been taking place for a year, it's possible he didn't immediately develop the polaroid system and that even maybe Teddy had kept out of his way and tried to manipulate him by messages and phonecalls for most of the time. This is probably backed up with the "Never answer the phone" tattoo. At one point he realised he was being manipulated through it and tattooed that. Once he stopped responding to normal methods, Teddy realised he needed to guide him face to face
It's also possible that he hadn't met Teddy before. Except for the Photograph of Lenny that Teddy slipped into his room, every other piece of evidence we have that Teddy and Lenny have been doing this for ages was Teddy's story. It's possible Teddy got ahold of that photograph somehow, and when Lenny took his picture was the first time they actually met face to face.
Just how long does Leonard have before his memory "resets"? Some sources say 15 minutes but this time limit is only given for Sammy Jenkis Which is already a huge lie and we don't know how much of that is actually applicable to leonard. And it doesn't make sense, because after dealing with Dodd he heads back to Natalie's house and seems to still have an intact memory, but between those two scenes the sky has gone from day to night which is impossible in under 15 minutes. But on the other hand his memory resets while having that confrontation with Natalie which seemed to be less than 15 minutes. Is his conditioned just ill defined and he has no idea when he will just forget everything?
Nolan's DVD commentary describes Leonard as remembering things as long as he's paying attention, or can keep them in mind (I don't know if this is how the condition actually works in real life, but this seems to be the standard for the movie). In the case of Dodd, it does seem iffy that he can remember for that long, but it does seem that Leonard can keep his goals in mind while driving, and it is possible that a combination of this, and of having "ask Natalie" in the Dodd's bloody nose photo kept it in mind. In the Natalie scene, he got distracted, which lost the memory. (The movie still doesn't make complete sense even with this memory method in mind, since the black and white scenes seem to forget the condition at some points, but it will make somewhat more sense.)
My Psychology professor showed us this movie to illustrate anterograde amnesia, and it does basically work like that. Leonard can remember something for as long as he can focus on it. After that, it's gone. Knowing how to drive is a different kind of memory from knowing information (it's unconscious) so Leonard can drive and keep a single event in mind at the same time.
Specifically, knowing how to do certain things (drive a car, shave, or in Sammy's case, inject insulin) are all different kinds of what is called procedural memory (memory concerning skills) which operates in a very different way to memory of facts or people. There are reported instances of people with retrograde amnesia who can't remember their own names but can play a violin expertly, for example.
How about a notebook?
I have a very similar condition and keep notebooks, with tabs and post-its to mark where I wrote something down. Easier than a tattoo but less dramatic, I suppose.
Aside from drama, you could also say Lenny is paranoid, to him tattoos mean "this is permanent, it's definitely correct", plus he's sending himself a message "all this stuff about John G is serious, not just something you scribbled in a book one day" but he's already learned to trust his handwriting so it shouldn't be necessary.
Okay, maybe this was explained and I need to re-watch it, but isn't Leonard's quest for constant justice kinda screwed now that he's tattooed the license plate number of a dead John G. to his arm? How many identical license plates being driven by John G.s could there be?
Down the road, he'd realize it's a dead end or that the guy's already been killed. It's quite possible he'd alter the evidence again to keep up the illusion. We've already seen him do this once on camera, and it's implied he's done this several times before. He'd probably put a sticky note on his leg telling him to remove or alter the tattoo. It's not like he's let evidence stand in his way before!
Considering that Lenny has progressed from killing criminals to killing a cop, I'd say his days as a free man are limited.
An interpretation is that he didn't want to kill people, he was manipulated by Teddy to do so (well, the first guy was John G maybe but it's not confirmed either way, and while the rape seems likely the murder seems much less so). After learning that Teddy has been tricking him into killing criminals for him, he decides to set things up to kill Teddy and "get his man" at the same time, ending the cycle.
I think he wanted to end the cycle. The voice-over when he writes it down suggests he wants Teddy to be his lasting vengeance. He takes Jimmy's car because he wants people to recognise him and link him to Jimmy, which as well as helping get Teddy probably is also making sure that he'll get locked up after this
There is also a split-second shot at the end of Lenny in bed (with his wife?) with a tattoo over his heart that says "I did it", so I assumed Teddy would be his last kill.
The license plate is probably another part of his plan, it's something that would let him CONFIRM that "John G" is dead and was murdered. So even if he forgets to write it down, he'll know he's killed John G and his vengeance ends. And with Teddy dead, there's no one left around to manipulate him further.
Why did Leonard switch clothes with Jimmy Grants?
One person in the previous entry mentioned the possibility that he wanted to be recognized and get caught. While that's possible, I think he did it for the opposite reason, to alter his appearance quickly. He goes from a guy in a pickup and dressed like a laborer to a fancy suit and a Jag. Teddy didn't seem to find it odd that Leonard was doing this, so it's possible that he's done it before.
How does Leonard know he has amnesia? How come he does not spend every new loop figuring out that he cannot remember anything?
Leonard's pre-accident experience with this type of amnesia is through meeting Sammy. Your and my previous experience with this type of amnesia is through the film Memento. Therefore, if you were to find yourself in a park, sitting on a bench, with no recollection of how you got there, no familiarity with the clothes you were wearing and no concept of what time it was, the first thing you might do as a reflex action is look at your watch. Instead of seeing the watch, you'd see a small note that says 'Remember Memento'. All it takes to put two and two together is a bit of mental sharpness, helped no doubt by having done this same thing, hour after hour, day after day, for months/years.
This also falls under the 'conditioning' explanation. He's had it for years, so it's managed to penetrate.
Why doesn't Leonard write specific dates and times on his notes to keep track of their order?
It could be he doesn't want to, it's part of the thing Teddy was talking about with Leonard altering his memories through conditioning. He doesn't want the information to be too specific, so he can interpret it to fit whatever his current circumstances are. The thing with putting down Teddy's license plate is a departure, because that time he was specifically targeting Teddy, and wanted to make sure he got the job done.
Alternately, it could be that he has his own system that doesn't require dates. Everyone's got their own personal way of doing things, and often a person's system only makes sense to himself.
If he remembers things from before the attack that lead to his injury, why has he never called or sent a letter to any family members or friends?
It would be a little difficult to explain to family and friends that you, a formerly mild-mannered insurance investigator, are going on a quest for revenge.
Possibly he had no family or friends apart from his wife. Might help to explain his devotion to her.
When Leonard got the tattoo, how did he remember that the "I" wasn't a "1"? The way he wrote them, they looked the same, and the tattoo lady put a "1" on his leg. While Leonard was a very observant person, I doubt he paid attention to the pattern of letters and numbers on the license plate.
Even if he did screw up one letter for a number, it wouldn't have really mattered. If you put in a license number when searching for who owns the car, it would still come up as Teddy owning the car. All Natalie would have to say is that find out who owns this number and the person might have the name John G. Typically you only need a few letters to search for the car (hence why cops can catch you on cameras even if you have a few numbers blocked). It is also somewhat implied that Natalie met Teddy before so once she saw his picture she knew he was a cop.
There are actually some letters that can't be used in official identification like plates and licenses. I and O are among them because they resemble 1 and 0 too much in non serif text. This is also the case in insurance, which was Leonard's job. So he would know this.