Because American Sign Language (ASL) is a language without a writing system, the study of historical change in ASL has been almost impossible. No data are available from written materials on early forms of the language, except a few sketchy descriptions of how some early individual signs looked.

However, in the early part of this century, the National Association of the Deaf (NAD) created a set of films of the most fluent 'sign masters' of the time. Their goal was to preserve and demonstrate the sign language of the epoch. Twenty-two films were made between 1910 and 1920, fourteen of which have survived. They featured speeches, poetry and stories performed by twelve master signers. The master signers were of different ages, providing a sample of three generations of ASL users at the time. The original copies of the NAD films are stored in the archives of Gallaudet University and the Library of Congress. In 1997, Sign Media, Inc. produced a videotape copy of the NAD films. These films have turned out to be a rich source of material for analyses of historical change in ASL.

An important goal of this project has been to use the NAD materials to analyze how ASL — a relatively mature and quite complex sign language — has developed its linguistic complexity over generations of users and through historical change. Most of our understanding of the history and diversity of human language and language change comes from research on spoken languages. The literature on historical linguisitics suggests that language change should occur in particular specifiable directions.

At the SLRC, we are working to determine whether these universals of language evolution apply to sign languages as well.