The expansion of the opening in the iris of the eye. Pupil dilation is involuntary, and usually merely an adjustment to darker conditions, but it can also communicate emotional arousal (see alsoleakage). Even with photographs, viewers express more interest in an attractive model when the pupils are retouched to appear larger. In face-to-face interaction this kind of nonverbal signal is neither deliberately intended nor consciously noticed, so if we count it as an act of communication then it reminds us that neither of these is a necessary condition for communication.
Subjects: Media Studies.