Fraiberg and her co-workers studied ego development in children with three kinds of defects: blindness, deafness, and thalidomide birth defects. With "proper" mothering, the traumata resulting from all three defects were eventually overcome. The most striking finding was that blind children show the greatest lag in ego development. Thus vision appears to be the most important biological given, without which "abnormal" ego development will occur. It must be noted that autism occurs much more frequently in blind children than in sighted children, but only when the "mothering" was inadequate.