Getting Over the Yips
I first encountered yipping when a professional I knew talked about the "live snake" in his hands as he was over the ball on the putting green. I had no idea what he was talking about until I watched him putt. And there it was. It was as if the club developed a life of its own once he tried to move it.
It was hard to believe. I met an amateur who yipped so badly I had to resist the urge to laugh as I watched. It seemed so exaggerated, I thought that my friends must have sent him to me to as a joke to warn me not to take this mental stuff too seriously.
At its worst it is almost impossible to believe that yipping can be real, the movements so random and jerky. In trying to get to the root cause of yipping, we typically find that some past event triggered in a player's mind a sort of mental self-destruct button. For example, you identify a putt that really meant something, a putt you really wanted to make, and missed. And the whole thing gets blown out of all proportion. As the (self-inflicted) mental anguish escalates, the significance attached to that one event affects the way you approach the next putt.
You are afraid that the same awful outcome might happen again. The fear response means you have a lot of negative thoughts, your blood pressure goes up, your breathing becomes shallow and your muscles tighten, ready to deal with the 'threat'. All these have the potential to create the yips. All that muscle tension makes it very hard to control the very small, subtle movements required for good putting.
So what do we do about it? Given that it is generally thought to be a fear response, we can look at ways to reduce the fear. You need to focus your attention on something that is easy to control, so that you don't perceive there to be a threat, or at least the threat seems smaller. In other words, you have to change what you think about and pay attention to.
The most reliable way I know of to do this is to turn your attention to your breathing pattern. Do all your usual pre-shot routines such as reading the green, practice swings, etc.
Then, either before or as you take the putter back, breathe in. The timing of this in-breath seems to be an individual preference. Some people like to inhale before they take the putter back, others prefer to do it as they take the club back. Then comes the most critical part. Just as you are about to make your through-swing and stroke the ball (i.e. as the club moves forward towards the ball), breathe out in one long, smooth, even breath. Make sure there are no sudden whooshes. The key to this exercise is the smoothness with which you exhale. Generally speaking, the softer your breathing, the slower you will strike the putt; the harder you breathe out, the harder the putt.
This technique works because our breathing is one of the few things we have control over, even when we are under pressure. Breathing out is a reliable way to relax the muscles (hence the old cautionary saying "Take a deep breath"). When you have a lot of attention on your breathing you have much less attention on the one thing you are afraid of (i.e. missing the putt), and without negative interference you are therefore less susceptible to the the "fear" response.