When I was a kid, I played cello and bass, which were tuned in 4ths and 5ths. I could go back and forth between the two instruments without batting an eye, incl

When I was a kid, I played cello and bass, which were tuned in 4ths and 5ths. I could go back and forth between the two instruments without batting an eye, including sight reading. I think you just develop two parallel mental circuits, and there are enough sonic and tactile clues that you don't forget which instrument you're playing. After high school I played bass exclusively for almost 40 years, and during the pandemic I got my cello out again. After several weeks, the old circuits started to re-attach themselves again. In my case I'm trying to play jazz on both instruments, which includes improv soloing. Let's just say that's a work in progress. There is still a lot of stuff I can play on bass, that I can't approach on the cello.