Eyebrow_flash
The eyebrow flash is an unconscious social signal, a raising of the eyebrows for about a fifth of a second that communicates a wish to approach another whom the sender recognizes and is preparing for social contact (such as a greeting).[1][2] People generally return an eyebrow flash, unless they do not recognize the sender, or the sender looks away immediately after.[3] The message must be interpreted in context. Psychologists and sociologists say that eyebrow raising can be a reaction to fear or surprise.[4]