In the research on positive emotions we find that positive emotions broaden your perceptions/thoughts/behaviors, while negative ones narrow them. The idea is that deep in our evolutionary past, our ancestors faced very specific threats, and our bodies have evolved to attend to these threats in specific ways, to the exclusion of other things in the environment.
For example, if there's a dangerous predator nearby, you don't want to be caught admiring the pretty daisies. So your whole body shifts perceptions and resources to prepare you to run or fight. But when things are going well, when there's no particular threat, it's better to broaden your perceptions and the potential thoughts and actions you can take, so that you can expand, build resources and make new allies.
Hence, positive emotions counter the physiological effects of negative ones, allow more divergent thinking, and help you to processes faces more globally, rather than focusing on particular features, as negative emotions would tend to lead you to do.
Patti Wood, MA, Certified Speaking Professional - The Body Language Expert. For more body language insights go to her website at www.PattiWood.net. Check out Patti's website for her new book "SNAP, Making the Most of First Impressions, Body Language and Charisma" at www.snapfirstimpressions.com. Also check out Patti's YouTube channel at http://youtube.com/user/bodylanguageexpert.