Anyway, I was just trying this on this week - uncomfortable as this can be - and it reminded me how freeing it is.
Here's how it goes: You use your judgement of another to see something about yourself. Check to see if that thing which you are accusing isn't also you and if you can't find it in you, check for the shadow (the opposite) of that thing. Now in order to make '3 fingers' work for you, be willing to use the information as revelatory, not accusatory. In short - no beating yourself up! It's all about understanding that we are all a little bit of everything, which allows you to get off of other people's backs, release you both from all the hellish things that you think (projections) and give yourself half a chance of actually seeing them for who they are.
When you see that the ammunition you are using against a person is actually part of you too it helps you soften to them and to yourself and sometimes even let go and connect more.
Here's my example:
My swift judgement was that someone was "confused and not together". As soon as I turned this back to me, it immediately occured to me: "I'm a know-it -all'." I often think that I am supposed to have all the answers and have it all together ALL the time. Of course I would pick on someone I think doesn't! What a classic projection. Of course, this is also a very painful way to live because it allows me no mistakes. Imagine, it doesn't work all that well for me, but I want her to 'get it together'. Wouldn't we both be better off if we just lightened up?
Seeing this has allowed me to let go completely of my judgement of this person and just be ok with who we both are.
What a relief.