There is more to a baby's face than meets the eye. Psychologists at Wesleyan University in Middletown, Connecticut, documented greater emotional intensity on the right side of infants' faces while the youngsters smiled or frowned. Curiously, previous studies found emotional expressions are more intense on the left side of the face among right-handed adults.
Researchers think the adult pattern is influenced by the right side, or hemisphere, of the brain, which controls most muscles on the left side of the face and is critical in producing emotional displays. The left hemisphere controls much of the right side of the face, and is thought to inhibit emotional expressions, thus contributing to more intense expressions on the left side.
The examination of babies' faces suggests the right hemisphere matures more quickly during infancy, according to study director Catherine T. Best. At first, it apparently dampens the expression of spontaneous emotions, then gives up that function as the left hemisphere matures during childhood. Further study of facial expressions may clarify the ways in which infant and adult brains handle emotions, Best said.(Funk & Wagnalls new Encyclopedia of Science Yearbook)