PLS HELP! What is Kleinke, Peterson, and Rutledge's theories on facial feedback? I can't find anything online, but maybe I'm just not looking in the right places.

(This would be related to psychology, but they don't have that choice for a topic)

Thanks in advance! :))

Aim: To examine if facial expressions would have an effect on positive and negative moods (facial feedback)

Sample: 131 undergraduate physiology students

Methodology: The experiment was described as a study of how accurately people can communicate facial expressions. Participants were shown a series of photographs and asked to mimic the expressions. One group was given a mirror to look into and the other was not. There was also a control group that did not mimic the expressions and instead were asked to keep a neutral face throughout the study. Mood assessments were taken at the beginning and end of the experiment.