During an instrument flying lesson (on a RedBird FMX full motion simulator at KJYO) I had something new happen a couple of times recently. My instructor regularly includes some new experience in my instrument rating training and instead of having me in the cloud deck right after takeoff he had me go through it and climb to the cloud tops. The result of this was that I was just over the clouds and could see them moving below me. In the first case I was in a turn, got to the tops and then because I could see them I had an immediate visual sensation that I was moving much faster than I actually was. I almost pulled back on the throttle because of the effect but I checked the pitch and airspeed and could see that I had not suddenly accelerated. During my primary training my instructor pointed out that flying in the clouds (particularly with lights on) might cause this feeling but this was the first time that I had experienced it. The experience definitely reinforced that you rely on the instruments and not your eyes. It also gave me even more respect for my instructor in exposing me to the plethora of things that might happen to you in aviation.