James-Lange Theory of Emotion: A theory suggesting that our physiological reactions (like smiling or frowning) occur before we experience emotion – this theory supports the idea behind the Facial Feedback Effect.
Body Language:Non-verbal communication through conscious or unconscious gestures and movements - this ties in with Facial Feedback Effect as our body language (including facial expression) can affect our mood.
Emotional Contagion: The phenomenon where people tend to catch feelings from others - if you're smiling because of the Facial Feedback Effect, others might start to feel happier too!