link1264: Similar things happen in combat sports, especially MMA. There have been times where a fighters is "out of it" by still concious, the ref steps in to stop it, and the fighter ends up attacking the ref because the fighter still thinks the fight is going on because his brains are so scrambled at that moment.
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That's a completely different thing, reacting out of instinct... the closest I've been to that, is playing football, where I collided with a TE, everything went black of a sec, I got up, jogged to the sideline, took my hat off, kneeled down, asked for water, and thought I was getting patted on the back by my teammates, when in reality was the other team's coach asking my if I was feeling ok, I was told afterwards :)
Given the scene, Henslet had just gotten hit somewhere in the head, but given the expression shown and the music played in the cut scene, I took it more as a sign of rage, more like "how dare this priest tell me what to do", and smashing him against the rock was more of a sign of disdain.