- the high visual weight of the human face;
- the high visual weight of the eyes in the human face; and
- the Gestalt theory of Continuity.
If eye-lines are present in a composition, they will nearly always be important structural elements because of their hard-to-dilute inherent power of directing the viewing eye. Eye-lines take two common forms:
- Direct eye-contact with the viewer
The observer has direct first-person involvement with the image. This kind of eye-line is the highest attractant.
- Looking at another object
Used to point out an object of interest, the observer has a third-person involvement. If the eye-line is directed at something out of frame, this introduces ambiguity which creates either delay or a sense of suspension.