Expressive Eyes
The eyes act as an emotion intensifier. They can't change an expression from happy to sad, but they do help delineate the degrees between being pleased and being thrilled. Moreover, emotions range far beyond happy and sad — and the eyes can be the conduits for this transformation.
The direction of the eyes can also help shape the mood of the face. For example, eyes that look up can add a sense of detachment to the expression. This is useful when trying to express a look of innocence or nonchalance. Eyes that point down can signify shame or secretiveness. A mischievous schemer might have her eyes down as she hatches her plan.
Eyes modify the intensity of the emotion.
Wide Eyes
The eyes convey most of their emotion through their size. Large, circular, wide-open eyes lend a sense of excitement and urgency to the face. They have the effect of taking the general emotion on the face and adding a charge to it. Happy becomes ecstatic and sad becomes shocked or forlorn.
Dilated pupils — an effect of inebriation — are another example of how cartoon imagery has roots in human physiology. If the pupil is over-dilated, the character seems to have lost control of his emotion. Underdilated pupils can indicate shock or sickness. Uneven pupils signal confusion.
Half-Lidded Eyes
As the eyelid closes over the eye, the eye stops magnifying emotion and starts to diminish it. Small, squinty eyes have the opposite effect of wide eyes — they drain the energy from a facial expression. On a smiling face, squinting eyes can make a face less happy. An angry face turns into a brooding face when the eyes are partially closed. In each case, it's a muted form of the same emotion.
Uneven Eyes
“Uneven eyes” describe expressions in which the intensity of one eye does not match the intensity of the other. For example, one eye is wide open and the other is half-shut. Predictably, this adds a sense of confusion to the face. The sense of puzzlement grows in strength as the difference between the two eyes increases.
Closed Eyes
Closed eyes usually turn the emotion inward. The facial expression becomes directed at the person expressing the emotion. A smile becomes smug satisfaction when the eyes are closed; a frown becomes shame.
