A pair of studies looks at the look of love:
And in another:
Volunteers looked at faces with exaggerated or reduced male or female features; the faces had been morphed to look either more or less masculine or feminine. As the faces flashed on a computer screen, the volunteer was supposed to hit a key as quickly as possible to indicate whether the face was looking at them or away from them. Both women and men could do that more quickly when the face had exaggerated sexual characteristics.