I have this problem too. My T picked up on it very quickly and she knows that it is often a defense mechanism for me. Sometimes I really don't know because I have done such a good job blocking things out that I can't even think straight. Anyway, I find it is helpful for me to write things down and read them in session. Having my thoughts write out and not all jumbled in my head helps me to reflect on things and answer her questions better. Often after having 1 or 2 productive sessions I will start shutting down again. My T described it as slowly chipping away at a block only to have someone putty over it. It is a slow and painful process