Just curious, why is this a problem-does it affect how the chord sounds? Other than it being just a visual thing that looks odd?
If there is something in place to create sufficient desire to overcome the problem, I guarantee that the problem will solve itself in the majority of cases.
I feel that bringing a problem to light and focussing on it may actually be all that is needed to correct it. Frequently, I have found, there is not enough 'desire' to correct the problem by the student who will often be quite happy to take the easy way out and leave the hand as it is. If there is something in place to create sufficient desire to overcome the problem, I guarantee that the problem will solve itself in the majority of cases.
I disagree. One may actually make things worse, or not look in the wrong place. I suspect that the effort to not have collapsing joints may actually be causing the problem in this case, for example. Finding the cause, and thus solution, is key I think.
I think it is highly possible it appears in other situations too so any exercises which allow the student to focus on NOT allowing the knuckles to sink will be helpful.
I almost agree, but in my experience focusing on NOT doing something is usually doomed to failure. The focus must be on DOING something else correctly. (probably that's what you meant, but just in case)
Meanwhile a thing somewhere else can cause a problem. Poor balance in the lower torso can cause a tense back can cause something wonky in the little finger: but because you're worried about the little finger, and no matter how much you fuss about it, nothing changes, because the problem is actually about shifting your weight on the bench. etc.
(As a side note and at the risk of being really annoying, (and I apologise in advance for this; you are welcome to ignore this suggestion) but can I just add that by saying, “but in my experience focusing on NOT doing something is usually doomed to failure.” you are very likely limiting yourself by your own beliefs. The act of saying and believing this will pretty much ensure you are correct in your thoughts.)
It might be useful for Psykopili to make a video of his / her hand playing the same chord, from the same angle, so as to get some extra clues. I'm playing on a hunch here.