Well, I see humans sometimes as simple machines. We have
   anticipation/expectation mechanisms always functioning. We have
   receptors that bring in reality. Then we have comparators
   inbetween. [yes, it's a computational metaphor] When the
   anticipation doesn't match up to reality, we react. In short,
   these reactions are expansions of cognitive dissonance. Of
   course, computational metaphors aren't as fun as evolutionary
   ones smile emoticon