Understanding and simulation
't Hart examined how we understand language, especially language that refers to emotions. Current theories suggest that, as part of our understanding of the word 'angry', we simulate the emotion with our facial expression. This can for example be seen in the corrugator supercilii, the frown muscle, that will tighten slightly.
Good or bad characters
In his research, 't Hart looked at how a word like 'angry' is treated in two different situations: 1) if it describes the emotion of a nice or good character and 2) if it describes the emotion of a mean or bad character. His research showed that we deal with the same emotion-related stimulus differently depending on the further emotional context, especially our evaluation of the situation being referred to. This was evident from the frown muscle activity measured in his experiments.