The eyes focus in multiple imaginary triangles.
Eye Movement The view focuses either between
(A) eyes and forehead (business look)
or (B) eyes and mouth (friendly look)
or (C) eyes and chest or crotch (intimate look).
If eyes meet for more than two thirds of the time, the other person is either interested (dilated pupils) or he/she puts out a non-verbal challenge (constricted pupil). If a person likes the other, he/she often looks back. This has the effect that the other person may realize that he/she is liked.
This is one out of 63 gestures from the body language trainer.