Eidetic memory comes in grades. It usually seems to make use of or abuse spatial memory to remember facts in great detail that you then synthesize into semantic information. See "memory palace."

Eidetic memory used to be considered a negative mutation in that the bearer was not "properly using" their semantic memory, i.e. just remembering the fact without having to synthesize it from a raw sense memory.

From Wikipedia on eidetic memory:

> To constitute photographic or eidetic memory, the visual recall must persist without the use of mnemonics, expert talent, or other cognitive strategies. Various cases have been reported that rely on such skills and are erroneously attributed to photographic memory.

Eidetic memory is exceedingly rare more on the "single digit adults have ever had it", many scientists don't believe it is a thing. However, you also have things like:

> von Neumann also possessed the power of absolute recall. Once he was asked to recite “A Tale of Two Cities” before being asked to stop after a perfect 15-minute recitation.

> John von Neumann was able to memorize a column of the phone book at a single glance.

This is on a whole other scale than what the original poster said.

True, but note it is consistent with what I gave. There is more to memory and the study of the mind than Wikipedia. There are people with very good recall that do not fit that definition, or who recall things in a different way, but share similarities.

No, you said eidetic memory comes in grades. It does not, it is a binary ability the same as perfect pitch. Obviously there is more to memory than an ultra rare ability, but that was never part of this discussion.

> eidetic ī-dĕt′ĭk adj. Of, relating to, or marked by extraordinarily detailed and vivid recall of visual images.

There are grades of "extreme detail" ranging from instantaneous recall of your lunch three years ago as well as what everyone was wearing and what you were talking about to very very well above average recall of useful information in the form of sensory memory.

The justification for this interpretation is on Wikipedia and is related to the physiological explanation of eidetic memory. Instead of semantic memory sensory memory is used, and you can see this occur to various degrees in people.

The qualifiers are loose and mean different things to different people. You are not sovereign of the English language. The second definition given in my source matches yours, but it is not the only one.

The English language isn't sovereign to scientific terms, the science community is. If you pulled out a dictionary definition of "policy" in the reinforcement learning community, you would be ridiculed. These terms have clear and agreed upon definitions.

Etymology or dictionary definition is not 1:1 with a scientific term.