What is an eyebrow-raiser?

An eyebrow-raiser is an expression or gesture made by raising one or both eyebrows, often to express surprise, disbelief, or skepticism. It can also be used to convey interest, curiosity, or amusement, and is commonly seen in conversation as a nonverbal form of communication. The eyebrow-raiser is a quick and involuntary facial movement that involves the contraction of the frontalis muscle, which connects the eyebrows to the scalp. It is often used in conjunction with other facial expressions to convey a range of emotions and intentions, and can be a key component in understanding social interactions and nonverbal communication.