So for a source, I would recommend "The Highly Sensitive Person". The theory is this: some people are more sensitive. They pick up on the microgesture you maybe dont. They hear the small vocal cue or see the change in posture. Our brains -- thinking in general -- its expensive! If you process things more quickly, it's plausible your batterys drain a bit quicker too. Evolutionary speaking, everything has a cost. Look is this true? I dont know the science has to be sorted out, but it is plausible.