I assumed the books were somewhat fictional (i.e. they were Gladwell-style) because if he meant to make a claim seriously he'd have published in a medical journal instead of a popular/literary book. But since writing the comment above, I've learned that over the years many people actually believed that all details in the books were literally true (you can search for e.g. [Sacks prime] to see many people who took the story seriously and analyzed them), which does put things in a different light.
I’ll do you one better, I believed Gladwell wasn’t writing fiction either.
Not OP but I guess Gladwell-style can be understood as writing that is presented as nonfictional but has more in common with fictional writing.
To me, it's when narrative has priority over accuracy. There are a number of popular edutainment figures who fit this mold, but Gladwell is probably the most prominent example.
if I search for Sacks prime, I get articles about Ulam spiral
what exactly was I supposed to find and see people believe?
Interesting, there seems to be a different Sacks (software engineer Robert Sacks) who devised his own Ulam-like spiral.
Anyway sorry I didn't keep track of the pages I visited, but here are some of the search results I see now, indicating at least some time wasted exploring something that did not need to be explored if it had been clear that the story was not fully real:
- https://empslocal.ex.ac.uk/people/staff/mrwatkin/isoc/twins....
- https://www.goertzel.org/dynapsyc/yamaguchi.htm
- https://www.pepijnvanerp.nl/articles/oliver-sackss-twins-and... (pretty good article!)
- https://www.ams.org/journals/bull/2005-42-01/S0273-0979-04-0... (mention by Granville!)
- https://blog.computationalcomplexity.org/2009/09/possibly-re...
- https://www.discovermagazine.com/oliver-sacks-and-the-amazin...
- https://forum.artofmemory.com/t/prime-numbers-mental-calcula...
BTW the same account of the twins (https://archive.is/MmogP) also has several paragraphs revealing major misunderstandings on the part of Sacks, e.g.:
> And yet they are called “calendar calculators”—and it has been inferred and accepted, on next to no grounds, that what is involved is not memory at all, but the use of an unconscious algorithm for calendar calculations. When one recollects how even Carl Friedrich Gauss, at once one of the greatest of mathematicians, and of calculators too, had the utmost difficulty in working out an algorithm for the date of Easter, it is scarcely credible that these twins, incapable of even the simplest arithmetical methods, could have inferred, worked out, and be using, such an algorithm.
[Needless to say, calculating the day of the week for a fixed date is a much easier and completely unrelated problem to that of Easter, “the first Sunday after the Paschal full moon (a mathematical approximation of the first astronomical full moon, on or after 21 March” https://en.wikipedia.org/wiki/Date_of_Easter ]