Please stop talking about Human Factors/Ergonomics.
As a Mechanical Engineer who also decided to add Ergonomics electives to my degrees the entire "science" behind it borrows 99% from Kinematics [minus the actual Kinematics calculated as it's punted to us Engineers] and 1% Psychology BS.
Funny, that's the same ratio of perspiration to inspiration as in genius...
You can't get very far with a Psychology BS...more like Psychology PhD. Try to design systems based on 99% kinematics results in systems that miss the human aspect and addresses only the body aspect. As in "nice feeling tablet...too bad the workflow and usability sucks and it's as ugly as a brick".
I don't recall Tog's background but Jef's was CS and philosophy or music if I remember right.