[s_m_t]

All this tells me is that people report a wide range of levels of ability pertaining to some skill. You could find similar ranges of abilities in any skill but that doesn't necessarily mean there is anything fundamentally different about the people in that spectrum of ability except insofar as developing that skill has changed them. There could of course be a fundamental difference but I haven't seen anything to convince me of that.

[ajb]

Well, that's a different proposition: I think that if you were to query you'd find that people who experience strong mental imagery have done so as long as they can remember, and don't have the experience of needing to develop it as a skill. It's true that such data isn't in Galton's study; perhaps it's in others, but more simply, we can ask:

Anyone reading this who has strong mental imagery (video like): Do you remember ever not having it? consciously or unconsciously, did you ever have to work to develop it?