Newborns can taste your voice!

New fascinating finding from the labs of developmental neuroscience: all babies start out with synesthesia, a melding of senses in which stimulation of one sense or modality is experienced as stimulation of other senses as well. Many adults retain the trait of being able to "see" sound or even "taste" emotion. An infant begins life with intermingled senses because his brain is one big interconnected glob; he has far more neurons than at any other point in his life and more than twice the number of connections between them than he'll ever have again. This massive recursivity of neural connections usually dies off by 8 months through a process of neural pruning, resulting in the discrete sensory processing most adults experience.

Now the totally amazing thing: people on the autistic spectrum seem to miss the heavy bonsai-like neural pruning most infants go through before they turn one year old. Autistic brains are wired far more heavily than other people's; the cognitive trouble is caused not by a lack of brain cells or communication between them but instead by a surplus. Too much connection prevents any one pathway from "winning out" and that prevents associations from being made, which means the brain can't shape itself around experiences the way most brains can; there can be no formation of consistent patterns (learning). Adults with synesthesia seem to have hit the sweet spot between us mere mortals and the autistic spectrum. So is my understanding anyway, based on sources such as "Preverbal Infants’ Sensitivity to Synaesthetic Cross-Modality Correspondences" by Walker et al (2010), "Infants Possess Intermingled Senses:Babies are born with their senses linked in synesthesia" by Maria Konnikova in Scientific American Mind, and The Scientist in the Crib: Minds, Brains, and how Children Learn (2009) by Gopnik et al.