We use 100% of our brains. Different parts at different times. But only a total of 3% at any one time or the energy used to reset the neurons that fire in out brains when we think would overload us and our brains wouldn't be able to handle it.

And, yeah, I think it all comes down to adrenalin. I'm not sure blood-drinking effects our skills/strengths. Either that or, like you said, it's psychological.

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