👉 The smile fluid, also known as the Zung-Shaler smile, is a physiological response that occurs when a person experiences happiness or positive emotions. It is characterized by a series of subtle, coordinated muscle movements around the mouth, lips, and eyes. The smile begins with an upward movement of the corners of the mouth, followed by a slight lifting of the lips, and then a softening of the facial muscles, creating a gentle, symmetrical expression. This fluid motion is often accompanied by changes in eye movement and can include the release of tears and a slight widening of the eyes. The smile fluid is an involuntary response, reflecting genuine emotional states and is a key component in understanding nonverbal communication of happiness.
