Birds have a reputation of having rather simple brains. Sure, they can react to stimuli to avoid danger and survive, e.g. if I kick a chicken it will probably try to avoid me, but is this just automatic instinct or is there something deeper? Does something happen in the bird's mind along the lines of "boy that kick was unpleasant, I sure wish it hadn't happened and I hope it doesn't happen again"? Do birds experience negative emotions?