This is a very enlightening post as it describes the symptom of what repeatedly happens to me during competition. I've shot about 35 matches now, mostly IDPA but also USPSA and Steel Challenge. I generally do better during the early stages of a match, but find myself losing focus (and shots!) later on. The same pattern happened during an action pistol match yesterday. Afterward I'm self-analyzing, trying to figure out just why the wheels fell off. Then I stumbled upon this thread which describes exactly what happened (LIGHT BULB ON, EYES WIDE OPEN!). During the first stages I was ignoring what the others were doing and going with my own instincts. Then, without realizing it at the time, I started closely watching the shooters before me, intently discussing stage strategy with other waiting shooters, creating a mental checklist of "I need to do this here" and "remember to do that over there". My apprehension level jumped up and I took myself out. Thanks for this thread - recognizing a problem is a big step toward fixing it.
