How many rating points is a photographic memory worth?

Curious.

Tons !

Just imagine leafing through 300 chess books and remembering everything !

I just watched a chess documentary last night, and in it Fischer claimed not know any of the old master games by heart.

Ivanchuk also said he had 10,000 games in his 'personal database', but didn't manage to increase this number 

For Kasparov, I heard 50,000 in some documentary.

I used to know the answer  to this one, but I forgot. 

Interesting. Anybody willing to do some research on the other side of the issue? I'm a bit busy at work at the moment.

photographic memories do exist but these are exceptionally rare and these memories do not apply to everything experienced and these memories may not be recalled with the clarity of a photograph, i've seen art in which the artist recalls things down to the finest details correctly to the finest details of sights from childhood of a time long-since-gone.  often these things result from natural or latent talent combined with acquired skill.

I used to have a photographic memory, but it was never developed.

Can't recall.

Rating points have mass?

I wouldn't think it'd be worth a whole lot. I don't think memory would help you much outside of opening theory.

You don't place any value on coming out of the opening phase with a clear advantage?

For weak players a photographic memory probably is less useful than you would think.  Here's Dan Heisman's "thought experiment" on the subject of perfect memory (for opening moves)

Taken From his "Novice Nook" column at Chesscafe, found here:

http://www.chesscafe.com/text/heisman127.pdf

How much does memorizing extra opening moves help?

Try the following "thought experiment," which reveals quite a bit about the 

relative importance of memorizing opening sequences:

1.  Assume that when a player is "in the book" he can play at a 3000 

playing strength, but after he is "out of book" his strength returns to his 

current rating.

2.  Assume that because of the exponentially growing number of 

variations, as one studies further into the same opening line one gets 

diminishing returns. One cannot only learn fewer moves deeper per 

study time, but the chances that any opponent will play those moves also diminishes. If we lock the average player away for two years and 

he studies only opening lines, he can probably go about four ply (two 

moves) deeper before either his knowledge is exhausted or a similar 

rated opponent takes him out of book.

3.  Finally, compare three "theoretical" chess matches: In Match A, two 

GMs rated 2700 FIDE play; In Match B, two players rated 1700; and in 

Match C, two players rated 700.

In Match A obtaining a slight opening advantage is important. Because GMs 

rarely make big mistakes, it is possible for a GM to hold onto a slight 

advantage and play for a extended period – perhaps the entire game – for a 

win or at worst a draw. Therefore, although the players' strength may fall off 

300 points when they get out of book (3000-2700), getting a slight advantage 

out of the opening is a big deal for players that usually only make tiny 

mistakes.

In Match B the playing strengths fall off 1300 points (from 3000 down to 

1700) as soon as the players get out of book. That large drop-off means that it 

is very easy for the player who gets a slight advantage to throw it all away (or 

more) on any one move. A slight advantage might be the equivalent of less 

than a pawn, say 0.1-0.3 pawn equivalent, but players rated 1700 routinely 

make moves that are much less than optimum. In complicated positions, they 

err much more than that. 

So for players at this level getting a small advantage out of the opening is 

nice, but it is primarily the psychological aspect of an opening advantage (to 

give them some confidence) that helps the most. Learning a couple of extra 

moves will thus likely have a very small effect on the outcome of the game. It 

is much more effective to spend that study time learning to play better than a 

1700 once you are out of the opening! There's only approximately two moves 

that will benefit from the extra opening study, but more than thirty moves out 

of the book. Therefore, what you do after you are out of book has a much 

bigger effect than knowing two more moves, even if once in a while your 

opponent falls into an opening trap and you win the game immediately.

In Match C the situation deteriorates considerably, as the ratings fall off 2300 

points after the book moves. With this level of play, getting a slight advantage 

from the opening, or even a distinct one, is almost meaningless. The optimum 

learning strategy for 700 players is not to try to memorize more opening 

moves, but rather to learn how to identify and make safe moves, even in the opening.

Yeah, my first thought is it the usefulness scales up with rating.  But I do think it could be worth a lot.  Consider a solid player who spent 10 years hovering around 2000 level. 

A total guess of course, but if they were able to memorize a few thousand GM games during that time I think that would be worth maybe 300 rating points or so because their analysis/understanding is likely competent enough after 10 years as an expert, they just can't discard poor moves/plans as quickly to spend time on the correct ideas.

Again, a complete guess, and the usefulness would vary from person to person.

Oh, and if all they used it for was to memorize opening moves, then probably worth a lot less until you're much further up there.  I think it would be much more useful to use a perfect memory on linking ideas to structures and positions as seen in GM games.  What worked, what didn't and why.  That sort of thing.

Interesting.  Another form is something I've heard called "autobiographical" memory where the person has "total" recall of everything they've ever experienced back to an early age... but I suspect after reading your link that they too only remember almost everything, and it's still short of total recall.

I think that a photograhic memory would help in end games as well and perhaps in the middle game with tactics and weaknesses in particular structures. 

Some value sure, but I was thinking about an beginner to strong-intermediate player, where advantages much less than a pawn don't mean very much. They mean something, but I don't think they mean a lot.

I don't know -- in those phases of the game you're really getting heavily into pattern recognition which is something else entirely.

Yeah, that's fair.  The same reason the win/loss percentage when playing white is higher for master level players than at the beginner to strong-intermediate level (where it's much closer to even).