New evidence that mothers possess a special brand of empathy comes from two studies reported at the conference.
In the first, researchers from the University of Milan-Bicocca in Italy recorded nerve signals from 40 volunteers-men and women, parents and non-parents equally split-while they looked at images depicting either happiness or distress in infants unknown to them. Both male and female parents had stronger reactions than nonparents to the pictures of infants in distress, and mothers had the greatest and most immediate response. There were no differences among the groups in responses to happy infants.
A second study, conducted at McGill University in Montreal, investigated whether a mother's empathy toward her own distressed infant influenced her perception of pain. The researchers had 12 mothers of young adult children immerse their right hand in circulating hot water for two minutes while watching a video of their child and of an unrelated young adult experiencing similar pain. The mothers subsequently rated their pain and estimated the pain of their child and of the other young adult.
Mothers' self-pain ratings correlated with how much pain they estimated their child to be in, but not with pain estimates of the other adult. Study author Catherine Bushnell postulated that the experience of watching one's child in pain activates emotional path-ways in the brain's limbic system, which in turn may alter the transmission of pain signals.