A Talk with Simon Baron-Cohen (Edge.org)
The results of the experiment were that we found more boys than girls looked longer at the mechanical mobile. And more girls than boys looked longer at the human face. Given that it was a sex difference that emerged at birth, it means that you can’t attribute the difference to experience or culture. Twenty-four hours old. Now you might say, well, they’re not exactly new-born, it would have been better to get them at 24 minutes old—or even younger. But obviously we had to respect the wishes of the parents and the doctors to let the baby relax after the trauma of being born. And let the parents get to know their baby. So strictly speaking, it might have been one day of social experience. But nonetheless, this difference is emerging so early that suggests it’s at least partly biological.