Why did Obi-Wan didn't seem to recognize the droids

He didn't own any droids so he was telling the truth. He just didn't admit to knowing them at all because at that point he was protecting Luke from the truth about the past and his father. If he had told Luke everything at that point it would have been too much for Luke to take in and the adventure may have ended right there. He had to come to terms about his ancestry gradually over the natural course of time which is what happened.

 

My current interpretation (after a couple of G 'n T's) is this: Both Obi-Wan and R2D2 are super sneaky and cunning and both seem like to hold their cards pretty close to their chests by default. R2 perhaps because of unique coding/errors/lack of memory wipes, and Obi-Wan due to spending a looong time on his own. PT Obi-Wan didn't have that shifty look in his eyes or manipulate others as disrespectfully as OT Obi-Wan did. I can suspend most of my disbelief with these assumptions. (Thanks Mr Guiness for your cunning acting.)

 

I have a doubt about R2's memory.
I think his memory is not intended to store events for years.
I think R2 just cannot remember long-aged events.
Why ? For two reasons that match.

1. Having such a long-time memory implies that there is a processor, or something able to analyze events as they occur, determine wether this event should be recorded or forgotten, etc... Just because any memory can store, over decades, every second of every day. Having such a filter involves a powerful artificial intelligence. If R2 was smart enough to do this, he would be smart enough to speak human language, and not blip-blip like a synthetiser...

2. Artoo is a simple astromech. He is a tool. He is not as evolved as 3PO whose function is "to interface humans and cyborgs".
Basically, Artoo's job is just to detect hardware malfunctions, and repair them.
I spoke of artificial intelligence. Consider the fact that 3PO's job is precisely to speak with humans, "understand" their wills and what they are telling to him, even remembers past acts with this human in order to understand better, and then translate it to the cyborgs. According to this, 3PO capabilities are much better than R2 ones.

In my mind, this explains that 3PO is the only one that can store events, and remember them.
I don't even believe that Artoo recognizes one human from another ?

 

This is exactly how I view it. Obi-Wan was intentionally hiding pretty much everything about Anakin, and R2 always does what he thinks is right, regardless of other opinions.

In the old EU there were some books called the Dark Nest trilogy. I wasn't particularly a fan of those stories, but they were the books where Luke more or less watched the prequels. Long story short: Artoo malfunctions, leading Luke to discover a bunch of heavily encrypted data in his old friend's memory banks. Artoo is obviously hiding something, even going so far as to damage himself in an attempt to keep his secrets. Over the course of the novels, Luke works to uncover those files—which turn out to be all about Anakin—and ends up witnessing several key scenes from the prequels. Artoo had hidden the truth from Luke (for decades) because he thought it was better that way. I could definitely see the little droid doing such a thing; Artoo's stubborn, smart and very protective of his friends.

 

That doesn't sync up with what we know about R2 in the films whatsoever. Additionally, his beeping rather than speaking would be based upon how he is built, not his intelligence. Also R2 is clearly a highly advanced droid with a clear sense of loyalty and heroism, which wouldn't make sense if he couldn't remember one person from another.

 

Interesting idea, daRinze. Welcome to the Cantina (If you're new to these parts!)

This is my preferred interpretation on Artoo Detoo too (couldn't resist ). Not only does this allow for great personality traits but is also along similar lines of some other EU narratives - I remember the X-Wing series portraying these astromech's as sensitive military equipment with an emphasis on discretion including memory wipes after missions. (Just today two F-16's were scrambled due to a military blimp going AWOL - I think militant rebels would take other mission sensitive information just as seriously!)

 

Thank you Moral Hazard.

Don't you think this is a little bit "too psychological" for an humble astromech ?

 

Obi Wan was getting older at this point. He had ceased his daily regimen of ginko baloba and ginseng and blue milk years ago. He had started to develop forcezheimer's disease, and couldn't be relied upon to remember things like he used to. The man thought Darth Vader killed Luke's father, for Cripe's sake. Talk about unreliable for information! It's no surprise that he forgot about the droids.

 

Not for Artoo. He's gone decades without a memory wipe and developed an extremely strong personality. We know that he can lie, "If you take off that restraining bolt, I can show you the rest of the hologram." Assuming that he hung around Alderaan a lot, I'd imagine that he'd been told to keep the secret from Leia, and he could easily think that he also needed to keep it from Luke.

Another (possibly more realistic) option is that Artoo didn't know the full story. He missed out on a number of scenes in the PT (i.e. being stuck outside in the speeder while Anakin was in the Temple slaughtering Jedi), and he had no reason to know that Vader was really Skywalker. As far as Artoo knew, Anakin died on Mustafar. I doubt that Luke mentioned the Cloud City confession (since he didn't tell Leia about it until they were chilling with the Ewoks), so it's possible that Artoo actually did tell Luke about Anakin at some point after ANH. That could even add a bit to Luke's conviction that Vader could be redeemed—he'd heard all of Artoo's tales of Anakin's heroism and bravery, and so that is how he viewed the past.