Answer:
the facial feedback effect
Step-by-step explanation:
The facial feedback effect refers to the impact of facial expressions on the emotional state of the individual. Also, forced expressions tend to make people more uncomfortable and unhappy even if they are being forced to smile like on social gatherings. Here, it is said that 'most recent participants reported feeling more happy than sad after rubberbands secured to the sides of their faces were stretched over the tops of their heads'. Hence, this is clearly the facial feedback effect as it highlights the impact of facial expressions on the emotional state of the participants.