in spoken English (see the discussion of Baby sign language). These studies also provided information on how young children learn to form ASL signs. More specifically, these data enabled Bonvillian (with Theodore Siedlecki) to develop an account of sign language phonological acquisition. Bonvillian also conducted investigations into the use of manual signs to facilitate communication in minimally verbal or non-speaking children and adults, such as persons with aphasia or an intellectual disability. In particular, he conducted a number of studies of sign language acquisition in children with autism. In the 1990s, Bonvillian (with Brenda Seal) examined sign formation difficulties in children with autism. This study made it clear that for manual signs to be used easily by children with autism, then the signs should consist of a single movement and be composed of a limited number of basic or unmarked handshapes. Over his career, Bonvillian contributed multiple articles and chapters on sign language, sign language acquisition, and sign language development to various encyclopedias, textbooks, and other forums focused on language development, child development, and/or various aspects of deafness. He also wrote multiple reviews of books that were focused on these research areas as well as on language development in special populations. Word recall studies In addition to word recall in deaf and hearing students being the topic of his dissertation, Bonvillian continued to perform a series of investigations into strategies or factors that improve (or inhibit) deaf persons’ and hearing persons’ recall of ASL signs and/or English words that had been presented to them. In one study, deaf students who performed the sign language equivalent of each English word in a list remembered more words than those deaf students using other recall strategies; English words rated higher in imagery value also were recalled more often than words with low-imagery values. In a sign recall study involving hearing persons previously unfamiliar with American Sign Language, different recall methods were encouraged in each of three experimental conditions; the condition in which the etymology or origin of a sign was provided along with its English translation equivalent resulted in better long-term sign retention. Project Koko Bonvillian wrote a review of The Education of Koko by Francine Patterson and Eugene Linden in 1982. Bonvillian and Patterson had known each other at Stanford University and had worked together with Koko the gorilla. They also had written an article on mother and peer attachment in rhesus