Mothers reveal their baby faces.

Mothers throughout the world talk to their babies using common conventions, such as raising the pitch and exaggerating the emotional tone of their voices. There's now evidence that moms in different cultures also use three distinctive facial expressions to communicate with their infants.

The three maternal expressions differ from adult oriented facial displays of emotion, such as those for happiness, sadness, and surprise, say psychologist Janet F. Werker of the University of British Columbia in Vancouver and her coworkers.

Puckering and slightly spreading the lips, often with a slight smile or subtle eyebrow raise, make a facial expression dubbed "oochie" by the scientists. Moms use this look to convey concern and caring, say the scientists propose in the September Infant and Child Development.

Raising the eyebrows sharply while opening and stretching the mouth, with a hint of a smile, yields the so-called "wow" expression. This display imparts a mother's sense of pride in her baby.

Finally, smiling and raising the cheeks with a slightly open mouth produces the "joy" expression, which also features what Werker calls "an unmistakable look of love in the eyes." Mothers adopt this expression to communicate a mix of affection and happiness, the scientists suggest.

Werker's team videotaped 10 Canadian mothers and 10 Chinese mothers interacting with their 4-to 7-month-old babies. Given a stack of pictures of the mothers taken from the tapes, 32 college students easily identified each of the expressions. Another 40 students and 35 mothers of infants reported close agreement on what each facial display meant.

Further research needs to explore whether mothers in other cultures, as well as fathers and nonparents, make the same three faces at babies.--B.B.