I think the cause is the same as a lot of bad shots. Throwaway and the urge the hit at the ball with the club head instead of the hands. The converse to this is then of course the quit stoke.
I think flip flopping between the two to prevent on or the other causes yips.
I think the route cause is mechanical and when it goes on for too long and becomes automatic it is then a mental problem
__________________ Yani Tseng, Go! Go! Go! Yani Tseng Did It Again! YOU load and sustain the "LAG", during which the "LAW" releases it, ideally beyond impact.
"Sustain (Yang/陽) the lag (Yin/陰)" is "the unification of Ying and Yang" (陰陽合一).
The "LAW" creates the "effect", which is the "motion" or "feel", with the "cause", which is the "intent" or "command".
"Lag" is the secret of golf, passion is the secret of life.
Think as a golfer, execute like a robot.
Rotate, twist, spin, turn. Bend the shaft.
There was a study done some time ago that identified the eyes jumping around in their sockets as characteristic of the yips. Some advocate moving the eyes to the leftmost part of the socket before putting. Your head straight down, eyes straight down, ball forward...then shift eyes left in their sockets to see ball/line before startup. Might be worth a try if it fits into your putting style.
I've come to understand that "anxiety" is always lurking around in two basic places.....past or future. When we allow it to creep into the present, whether we recognize it or not, we are no longer free to perform the task at hand. This is what I think the above mentioned studies prove. And they are proving the reactions to anxiety.
The secret, if you want to call it that, is to first realize that the body's system is nondiscriminatory. There is a lot of freedom in this understanding which allows you to proceed with developing a belief system. This would be the first steps to management rather than control. Letting go of control actually gives you more control....believe it or not.
The four steps to building a belief system are, trust, knowledge, management, confidence. These are things that can be measured, therefore managable. From there you can do drills that will take you to the next level....automatic. Golfing freedom.