By Carrie Gress

Thinking back to when my children were babies, I remember carrying each on my left side. Being right-handed, it seemed to make sense to hold a baby on the left so my right hand was free to do other things. My husband, however, who is left-handed, said he carried our children on the left side because it was his dominant hand.

Apparently (no pun intended), we aren't the only couple who prefers to carry our young on the left hand side. In fact, according to psychiatrist, philosopher and neuroscientist Iain McGilchrist, this preferred pattern has been around for millennia.

In his deeply insightful 2009 book, The Master and His Emissary, McGilchrist reports that "[t]he right hemisphere's affinity for both the perception and expression of emotion appears to be confirmed by the strong universal tendency to cradle infants with their faces to the left, so that they fall within the principal domain of attention of the adult's right hemisphere, and they are exposed to the adults own more emotionally expressive left hemiface." In other words, the right hemisphere of the brain is more focused on emotions and relationships, so therefore the left hand side, which wires to the right hemisphere, has an easier time of engaging with emotional triggers, like a baby. McGilchrist adds that "even left handed mothers display the leftward cradling bias." 

McGilchrist is generally critical of the popularized theories of right and left brain split, arguing that the brain is a much more complicated whole with the two hemispheres working together. Efforts to split them generally misses much of reality. But he adds that the left and right hemispheres have their own focus or work. The left hemisphere is generally focused upon the abstract, power, and utility, while the right absorbs content as a wider whole, including emotions and relationships. "The right hemisphere," McGilchrist explains, "presents individual, unique instances of things and individual, familiar, objects, where the left hemisphere re-presents categories of things, and generic, non-specific objects."

McGilchrist adds another reason for the left side cradling. "[T]he emotional impact of touch, the most basic and reciprocal mode of interaction, is also more direct and immediate if an infant is held to the left side of the body." In other words, if the child is on the right side, the left hemisphere of the brain first mediates the engagement with the child before signaling the emotional response to the right side of the brain. But if the baby is on the left, the emotions processed in the right hemisphere are lit up much more directly.

So the next time you pick up a baby, notice how you hold him. There might be much more going on than you might think.