1. Is Sign Language a Universal Language?
The United Nations page cites figures from the World Federation of the Deaf (WFD), stating that there are more than 70 million people with hearing impairments worldwide and that over 300 different sign languages are used [1]. As the phrase "more than" suggests, the number is not exactly 300. Sign language is not simply spoken language translated into hand movements. The UN explains that sign language is a natural language with a structure different from spoken language [1]. Just as Japanese and English are different languages, sign languages also have differences by country and region. The UN established September 23 as the International Day of Sign Languages, decided in 2017, with the first commemoration in 2018 [1]. So, if everyone in the same country uses the same sign language? Let us look inside Japan.
2. Do Sign Language Words Differ From Region to Region Within Japan?
Researchers associated with the Sign Language Research Center at Kwansei Gakuin University state that, like spoken language, sign language is not universal and has dialects, with expressions differing depending on the region where people live [2]. Japanese Sign Language is often explained as having nearly common grammar, with the biggest differences found in vocabulary. The differences between the Kanto (Tokyo area) and Kansai (Osaka area) regions are well known, but systematic research on finer classifications is said to be limited [4]. A survey published as part of Ministry of Health, Labour and Welfare research found significant changes in vocabulary usage between generations and regions in two areas: Tokyo and Kyoto. Furthermore, older deaf people reportedly used a wider variety of words [3]. Differences exist by region and generation, just like in spoken Japanese. How do these differences arise?
3. How Do Schools for the Deaf Cause Regional Differences in Sign Language?
Some families of deaf children do not use sign language. Therefore, schools for the deaf become one of the places where sign language is passed down. The National Museum of Ethnology explains that when instructors from other regions come to educational settings, their sign language can greatly influence the local sign language [5]. Mr. Maekawa also states that when teachers who know sign language move to another prefecture, the children in that prefecture learn that sign language and acquire it under the influence of teachers and seniors, so sign language changes depending on the environment [2]. In Japan, schools for the deaf were established in Tokyo and Kyoto during the Meiji era. It has been pointed out that these separate beginnings may be related to the formation of dialect differences between Kanto and Kansai [4]. However, schools are not the only reason; cultural differences are also cited [5]. If schools create differences, what happens in small villages without schools?
4. Why Do Hearing People Use Sign Language in a Japanese Fishing Village?
The Miyakubo district in Imabari City, Ehime Prefecture, is an area with many people who are deaf from birth. It is explained that a habit of using sign language without distinction between hearing and deaf people spread among neighbors and those in the fishing industry [6]. Imagining scenes where "pass me that" is conveyed by hand movements on boats or at the port, one can imagine how a life of communicating via sign language spread among both hearing and deaf people. As of 2016, out of a population of 2,736 people, there were 20 deaf people, and approximately 50 people were estimated to understand sign language [6]. The number of deaf people is less than 1% of the population, but the number of people who understand sign language is higher, suggesting that some hearing people understood sign language. Note that these are not current numbers. Similar examples are said to exist abroad. In the Al-Sayyid Bedouin village in the Negev Desert in Israel, hereditary hearing loss is common, and a unique village sign language is said to have emerged. Hearing people also used it, and a regular word order reportedly emerged [7]. However, since the figures are limited to encyclopedia introductions, we keep this as "it is said." Village sign language grew in small places. Do sign languages become similar or mix between countries?
5. Do Sign Languages of Different Countries Share Words or Mix Together?
There are reports that Taiwanese Sign Language, Korean Sign Language, and Japanese Sign Language share about 60% of their vocabulary, and historical connections with Japan are pointed out. There is also a view that classifies these together as the "Japanese Sign Language Family" [4]. However, the 60% figure comes from various reports. Taiwanese Sign Language is said to have developed uniquely, influenced greatly by Japanese Sign Language but also by other sign languages [4]. American Sign Language is introduced as having grown from a mix of French Sign Language and signs used within the US and in families, sparked by a school opened in Hartford, Connecticut, in 1817 by Thomas Gallaudet and the French deaf teacher Laurent Clerc [8]. There is a range in the dates of its establishment; 1817 is the year the school was founded. Japanese Sign Language and American Sign Language also borrow words from each other [5]. People and schools have helped sign languages become similar or mix. So, why not create a universal sign language from the start to overcome these differences?
6. Did the Universal Sign Language "Gestuno" Work?
In 1973, a committee of the World Federation of the Deaf (WFD) reportedly created "Gestuno," a common vocabulary collection gathering natural and simple signs used by deaf people in various countries. It is reported to have about 1,500 words [9]. This was a major attempt to overcome differences in world sign languages. However, when it was first used at a World Federation of the Deaf conference in Bulgaria in 1976, it is reported that participating deaf people could not understand it [9]. Today's "International Sign (IS)" is not a designed language. It is a naturally born method where people using sign languages from various countries at international conferences bridge gaps using common knowledge, pictorial signs whose meaning is clear, gestures, and signs borrowed from other languages [9]. IS came to be used, with participants drawing on shared knowledge, gestures, and borrowed signs. However, this explanation is based on encyclopedia entries. If one consults original sources, the number of Gestuno words and the situation at the time might be verified in more detail. So far, this seems to be about distant international conferences. But "bridging gaps" can be experienced at home.
7. Activity: Tell Yesterday's Events Using Only Gestures
Ask a family member to help you convey what happened the previous day using only gestures, without speaking. Discussing what you expressed first, which movements worked, and where misunderstandings occurred helps you understand the feeling of "bridging gaps." This is not sign language, nor is it practice for sign language. It is a slightly similar experience to the system of International Sign, which relies on common knowledge and pictorial movements as clues. To learn sign language, it is best to learn from people who actually use it. When conveying messages with gestures, do so in a wide space free of objects, and avoid movements that feel difficult or strained.