[QUOTE=anamnesis]
The characters fleeing through a flooded portion of a spaceship in Alien Resurrection…
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This was the example I was going to use!
I also do this when driving through tunnels tunnels.
No, can’t say I have.
[QUOTE=brazil84]
When watching a movie, I mean.
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I think it’s possible I might do it to an imperceptible degree, but I can’t say I’ve noticed.
However, if I ever see a drowning scene that involves Steven Seagall I will inhale very deeply.
No, but I often “time” scenes when a countdown clock has been set. Usually the actual time doesn’t agree, but I know of two cases where they do – that episode of TV’s MAS*H where the guy has a shattered aorta, and they have 25 minutes to replace it (there’s a clock in the lower corner of the screen. Which keeps going through the commercials), and the original version of Invders from Mars (the 1950s Menzies version), where the countdown to the explosion is timed properly, and seems intolerably long.
No, but depending on how bad the movie is, I may have the urge to laugh.
[QUOTE=Charger]
Now that I’m older, I have distanced myself from the “immersion” into a scene like that.
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Thinking about it, I think that “immersion” (haha) is what’s going on. If the movie is doing it’s job, part of you forgets about your own reality, and you identify with the characters of the movie. Subconsciously, you start to feel like the fantasy on the screen is your own reality.
Another example is if a character gets garotted, I sometimes get the urge to scrunch up my neck, chin, and shoulders.
[QUOTE=N9IWP]
Yes, I’ve done that - to see if the amount of time without breathing is resonable. (granted I’m resting on the couch and the hero is flopping around, but its a good 1st approximation)
Brian
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I’ve done it before, and I tend to test it when my bullshit meter goes off.
Yes, I do, and I also find my body rocking/moving/straining if I see the hero jumping, or trying to lift something, or grab something. It’s very physical, watching an action movie when you’re me. 
Only with Disney’s Robin Hood.
Yep, I do; and you should see what I do during the sex scenes . . .
This was a problem for me when I was a little kid, in the 70s.
PBS had Jacques Cousteau specials on a lot.
I solved the problem by turning blue, & fainting.
For real.