Thank you for offering feedback! The study you mentioned also references another that may indicate that further studies could be helpful to determine whether there is an effect “The results of McDonald, et al. (1988) suggest, inconclusively, that some personality changes may occur during SEAL training” (p 12). Generally speaking, your criticism is well-taken; I agree that the SEAL example is a difficult one because of the strong selection effects. Generally speaking, one should a priori expect more composite conscientiousness in any elite group (except maybe among artists?). One would have to diff-in-diff things to empirically determine an added training-based effect. My main qualm with the selection argument is it might elide differences between sub-traits of conscientiousness. “The average SEAL is also more persistent, reliable, and scrupulous, viewing life as a series of task- oriented challenges,” whereas BUD/S seems only to select for one of these sub-traits: persistence. Given that there is status associated with being a SEAL, we might expect Berkson’s Paradox to actually lead SEALS to be somewhat lower in the unselected sub-traits (task-orientation, reliable, scrupulous). Since this is not the case, we might adopt a null hypothesis wherein we expect that there is some add-on effect from training itself.That being said, you’re right that this is very far from conclusive. I suspect it would only really be compelling to those who personally witnessed the rapid shift in personality consequent to elite military training in an acquaintance. I count myself among this group, but recognize it may not exactly be a large % of the LW community — hopefully there the convergent cultural evolution argument holds a bit more weight?