Already at a few days of age, the child can discern the mother’s face, voice and odours from those of other women. However, it has not been known where in the baby’s brain this takes place. Of course, a baby’s brain is more difficult to investigate. However, a Swedish team (Carlsson m.fl. Acta Paediatrica 97:1221-1225) demonstrated that when babies of six to nine months of age compare pictures of their mothers with those of other women, their right-hand frontal and temporal lobes are activated. One could say that the baby from early on “decides” what part of the brain should be used in order to recognize faces. It is known that adults, too, work on their impression of faces in this part of the brain.
Furthermore, it has been known for long that the newborn can differentiate sad, happy and surprised facial expressions in an adult. Leppänen and coworkers (Infancy, 14(3), 346-362) showed in 2009 where this happens in the brain. Researchers are now beginning to understand how the brains of mothers and babies are working when they communicate with each other.
The next page shows two simple examples of the baby’s sensitivity of the mother’s signals and some other interesting experiments.