Have you heard the term “Bilateral Transfer“? One definition I found said, “a transfer of skills learned from one side of the body to the other. Although the skill was originally learned and used on one side of the body, the other side of it has the potential to learn this same skill.” (Thank you, internet Psychology Dictionary.)
Or to bring this closer to home, have you ever noticed when you make a shift with your left hand, your right hand (and your bow) tend to shift in the same direction? It happens without thinking about it. It’s a natural tendency and we all do it. Your body wants to be “in sync”. The right side does what the left side does. Unfortunately, this is not what we want to do when playing cello. We may be making shifts up and down the fingerboard with our left hand but we need the bow to continue going left and right across a string without moving up and down. This is how you will get better tone quality, which we all want. I’m as deficient in this aspect as anyone. Unless I ignore my left hand and focus completely on my bow hand, my bow will be shifting along with my left hand, which is NOT what I want. One way to practice keeping your bow steady and in one “channel” on each string is to play open strings very close to the bridge- almost on it. Watch yourself in a mirror and pay attention to the path your bow takes. It takes deliberate practice and concentration to work on this skill, but it is definitely one that will pay off in spades, and you’ll be “rockin’ it just like Yo-Yo” before you know it!