It has long been held that there are six universally recognized basic emotions that can be easily interpreted through facial expressions: happiness, sadness, fear, anger, surprise, and disgust. However, new research suggests that there are actually only four. Researchers arrived at this conclusion after studying the range of different muscles within the face involved in signaling different emotions as well as the time frame over which each muscle was activated. Read more in Current Biology.
RE Jack, OGB Garrod, and PG Schyns, Current Biology, 2014. DOI: 10.1016/j.cub.2013.11.064