From a New York Times obit by Katharine Q. Seelye headlined “Ursula Bellugi, Pioneer in the World of Sign Language, Dies at 91”:

Ursula Bellugi, a pioneer in the study of the biological foundations of language who was among the first to demonstrate that sign language was just as complex, abstract and systematic as spoken language, died  in San Diego.

Dr. Bellugi was a leading researcher at the Salk Institute for Biological Studies in San Diego for nearly five decades and, for much of that time, was director of its laboratory for cognitive neuroscience. She made significant contributions in three main areas: the development of language in children; the linguistic structure and neurological basis of American Sign Language; and the social behavior and language abilities of people with a rare genetic disorder, Williams syndrome.