The Double Pin Problem
Here is a tactical motif that I am struggling to master in my ChessTempo Saltmines training.
I've attempted the following tactical puzzle 22 times since February 15, 2016 and I've missed it 6 times. Of course, I'm only spending about 5-6 seconds on each attempt, as the Saltmines training method's goal is to solve a set of tactical problems repeatedly until the average solve time is only 8 seconds per problem and the accuracy is over 98%.
But, why is my mind occasionally refusing to see that there is a double pin here that wins and instead jumping to sacrificing the exchange for no reason? I've gotten it correct 16 times!
Since this problem is really a compound of two pins, one of which is a bank rank mate threat (a threat pin in NM Joel Johnson's terminology), I suspect that my intuition is just not adequately tune yet to threat pins, as the pin on the c3 pawn jumps out at me immediately.