Sylvester, the cartoon cat, and a system of signing developed by deaf Nicaraguans may seem an unlikely combination but new research, published in Science this Friday, has used both to shed light on how children’s natural learning abilities shape the fundamental structure of language.
Dr Sotaro Kita of Bristol University and colleagues in the U.S. and The Netherlands studied deaf users of Nicaraguan Sign Language (NSL), a new language created and developed by deaf people in Nicaragua over the past 25 years since the first school for the deaf was established in the late 1970s.
The researchers asked NSL users of different ages and Spanish speaking adults to watch a cartoon featuring the black and white cat, Sylvester and describe the action. The older NSL users had learned NSL immediately after its inception, and the younger NSL users had learned NSL after it had been passed on by generations of pupils in the deaf school.
The researchers then compared any gestures the hearing Nicaraguans made while describing events in Spanish with the signs employed by the NSL users.
In particular, they examined the gestures and signs that described complex motion events, such as when Sylvester, having swallowed a bowling ball, rolls rapidly down a steep street.
The researchers found that the Spanish speakers exclusively used gestures that depict manner (rolling) and direction (descending) of motion simultaneously, whereas the NSL users employed a mixture of sign expressions, some of which described manner and direction simultaneously and others separately. The tendency to separate manner and direction was strongest in the youngest NSL users, whose signing represents the latest development in the short history of NSL. Furthermore, NSL users hierarchically structured separate signs for manner and direction into a phrase.
This suggests that NSL started out by imitating the structure of real world events (in which manner and direction are simultaneous aspects of motion), using sign expressions similar to gestures used by hearing Nicaraguans. However, successive generations of deaf children learning NSL shaped their signing into something akin to other spoken and signed languages in the world, that is they segmented complex events into basic elements and then sequenced these elements into hierarchically structured expressions, according to principles not observed in gestures made by hearing people. Nicaraguan signing has thus been transformed from its early gesture-like form into a linguistic system within 25 years by generations of children learning and passing on the language.
Dr Kita said: “We propose that this early segmentation and recombination reflect mechanisms with which children learn, and thereby perpetuate, language. Thus, children naturally possess learning abilities capable of giving language its fundamental structure.”Paper
Ann Senghas, Sotaro Kira, Asli Özyürek: 'Children creating core properties of language: Evidence from an emerging sign language in Nicaragua.' Science vol. 305 no. 5691, 17 September 2004
Nicaraguan signing
Before the 1970s, deaf Nicaraguan children and adults had little contact with each other. Societal attitudes kept most deaf individuals at home, and the few schools and clinics available served small numbers of children. In this context, no sign language emerged. This situation changed abruptly with the introduction of special education for deaf people: by 1981, more than 200 deaf people were being educated together and numbers continued to grow throughout the 1980s. Although teaching was conducted in Spanish, these first children began to develop a new, gestural system for communication with each other. These gestures soon expanded to form an early sign language and this growing language has been passed down and relearned naturally every year since, as each new wave of children enters the community.
Today there are about 800 deaf signers of NSL ranging from 4 to 45 years of age. Previous research has found that changes in grammar first appear among preadolescent signers and soon spread to subsequent, younger learners, but not to adults. This pattern of transmission has created an unusual language community in which the most fluent signers are the youngest, most recent, learners. Consequently, the gestures of older signers retain much of NSL’s early nature, whereas younger, more recent learners, produce the language in its expanded, most developed form.
This study compared the signed expressions of 30 deaf Nicaraguans grouped into three cohorts according to the year that they were first exposed to NSL: 10 from before 1984, 10 from 1984 to 1993 and 10 from after 1993. All of the deaf participants had been signing NSL since the age of six or younger. Their signed expressions were compared to the gestures produced by 10 hearing Nicaraguan Spanish speakers while speaking Spanish.