Interesting technique. Great bassist. I posted previously that Al Jarreau had used 2 lefty upside down bass players in his band. The other was Chris Walker who's a baddass in his own right.
I know a few guys that play guitar upside down. Never saw upside down bass before. Pretty amazing. I can't imagine what it's like to learn an instrument backwards? Both right and left hand have to learn unique moves.
Jimmy Haslip (Yellowjackets, Gino Vanelli)? IIRC, he was the 1st I knew about. Keith Horne used to play in bars around here...you could sit about 5ft away. It was crazy times.
Stan Sargent’s technique is definitely unusual. I emailed him to ask how he does it, and he said that he thumps with his index and middle fingers, and pops with his thumb. Some of the others that I’ve exchanged messages with or spoken to (Alvin Mills, Larry Williams, Anthony Corley) do it the same as a righty by thumping with their thumb, and then moving up to pop with their index finger. Here are a few more for you. Examples of A Lefty Playing an Inverted (upside down) Righty