It's been a while, but I have a recollection of Foer going into the question of why more people don't do this in his book. It mostly has to do with the amount of time one needs to commit to practice, coupled with limited transferability of this skill.
To give another anecdote, I've worked with a very high-performing engineer who spent a bunch of his free time building memory palaces for new codebases to ensure retention. I'm sure he was above average IQ-wise, but his productivity likely benefited from his approach as much as from his innate abilities.
It also goes against common sense. Math, reading, and so many things are all learned, but frequently used by people who have a high IQ. Are we to assume that these things are not learned, because the author thinks IQ is the cause of reading skill, math, and similar things?
I've bothered going through the labor to learn the skill. I've seen my baseline measurement of recall ability improved by the training time I invested in learning the skill. I haven't bothered to get to a competitive level, but I don't need to do so to be certain that humans can learn skills by practicing them with the intention to improve.
The skeptic is just wrong. People can learn to improve their memory.
Critically, that doesn't mean that the skills aren't learnable. It means that people with the most advantages can exploit those advantages to gain a greater deal of advantage than someone who has less advantage.
> –One study showed that that training is non-transferable. This means if one learns a sequence of numbers, the skill fails when one tries to recite them backwards or a new set of numbers.
but just about every person who has ever memorized numbers with those memory techniques can recite the numbers backwards too. If you gain the skills to memorize one page of random numbers you can memorize a different one too, no problem.
Mensa? A low threshold, yet smart enough to be in the game if you can find something that really interests you. But you choose a club? Huh...
It's actually heartening that various people famous for their IQs have accomplished zilch in their lives other than being famous for their IQs. This tells you that the test is flawed, and that other factors determine revolutionary levels of success.
The magician/mathematician Persi Diaconis long ago explained to me about "memory palaces" and their effectiveness in competition. This can be generalized: The mountaineer Conrad Anker relays how European skiers can spot an American skier from far off: They waste effort. Many people had Michael Jordan's physique, but Michael Jordan spent a decade developing his physique into a world class athlete.
One is the architect of one's intelligence. The most poisonous aspect of IQ tests is that people believe them, and conclude that intelligence is innate, not malleable.
There are no peer-reviewed studies that corroborate the claims of the book, and research shows memory champions all have Mensa-level IQs. This is not surprising. Short-term memory is g-loaded and is a component of IQ test (it is called digit span or digit recall), so it is logical to assume that the best at memory would also have high IQs.