What have sign languages taught us about human language development?

by Professor Bencie Woll FBA

20 Sep 2024

Unlike most linguists, the languages I research are sign languages, and in particular British Sign Language – BSL for short. As the preferred language of around 50-70,000 deaf people in the UK, BSL is the third most widely used indigenous language in the UK after English and Welsh.

Just as the case for spoken languages, there are many sign languages in the world and globally over 8 million deaf people use sign languages as their primary form of communication. Sign languages have their own lexicons and grammars, and use manual articulators (the hands) and non-manual (body and face) articulators combined with the use of space for grammatical purposes to convey meaning. Sign languages have evolved naturally within deaf communities, and descriptions of the rules that govern them are an active area of linguistic research.

Sign language lesson with teacher and adult student
Sign language lesson. Image credit: Tayutau via Getty Images

Sign languages are not related to the spoken languages around them – BSL is not historically related to English: it has its own specific lexicon and grammar. Research on sign languages in the past 50 years has caused a revolution in linguistics, psycholinguistics and our understanding of the neurobiology of language. We can no longer think of language and speech as being equivalent. At the same time, there has been a revolution in public attitudes to BSL.

I'm involved in research on many different aspects of BSL and will focus on recent research in three areas: the brain and how deaf children learn a first language; new research on automatic translation between BSL and English; and recent political and educational developments in relation to BSL.

The brain and sign language: first language development in deaf children

There have been enormous technological and clinical developments in recent years – early diagnosis through neo-natal screening, and the provision of cochlear implants. These have all made huge changes. But still many deaf children have difficulties in developing full competence in English and in reaching educational standards comparable to their hearing peers.

There are still false beliefs that learning a sign language will have a negative impact on the learning of a spoken language – including a belief that the developing brain will be adversely affected by sign-language exposure. As a result, the majority of deaf children are only exposed to English. There are interesting parallels here to other false beliefs that, for example, there are disadvantages to learning more than one language as a child – that somehow being bilingual is bad for you. In fact, the evidence from my own and others’ neuroscience research is that early exposure to sign language provides a deaf child with accessible language before cochlear implantation can take place, and even when parents are not fluent in a sign language, learning a sign language enables a deaf child to acquire that first language with comparable early milestones to those for hearing children learning a first spoken language. And research has shown it has no effects that are negative on the brain or subsequent development of spoken language.

Automated translation between BSL and English

There’s been a huge revolution in machine translation in the past few years, that’s made texts in most of the world’s major languages easily accessible. Speech recognition is an everyday consumer technology, we just have to think of Google Assistant, Alexa or Siri. Even more than that, recent developments in Large Language Models (LLMs) such as Generative Pre-trained Transformers, better known as GPT, have led to new levels of artificial intelligence (AI) epitomised by ChatGPT.

However, these revolutions have occurred only with spoken and written language – automatic approaches to sign language recognition and production are lagging behind. And that’s because automatic conversion from a sign language to a spoken language, and vice versa, is a complex translation problem and one that currently is unsolved. We have been working in collaboration with computer vision scientists on creating the world’s first machine readable dataset of a sign language to be used for automated translation between BSL and English, and to provide automated tools to speed up the work of linguists in undertaking analyses of BSL and other sign languages. The ultimate goal of this research is to take annotated data and knowledge of sign language structure from linguistic research and use this to build a system capable of watching a human signing and turning this into English.

Sign language chart
Sign language chart, late 19th century. Image credit: Kean Collection via Getty Images

To achieve this the computer has to be able to recognise not only hand configurations and their movements but also facial expression and body postures of the signer. And it must also understand how these features are put together into phrases and how these can be translated into spoken and written language. So, it’s quite a challenge. This will be a world first and an important landmark for deaf-hearing communication.

We’re now even further planning to extend this work to create ‘SignGPT’, which will provide the sort of functions for the deaf community that are equivalent to what’s been provided for spoken and written language. This outcome will greatly enhance communication between deaf and hearing people, enabling full access to today’s information society.

Changes in society

Looking back to the time I began researching BSL in the late 1970s, it had not been used in the education of deaf children since the 1890s when it was banned from classrooms, although most deaf children learned BSL outside the classrooms because they attended residential schools for the deaf. Deaf adults were active organisers and participants in local, national, and international deaf communities in their activities, but BSL had no public presence: it wasn’t seen on television; there was no profession of BSL-English interpreting (interpreting was for the most part provided by hearing people from deaf families who had grown up with English and BSL); there were no opportunities for either deaf or hearing people to learn BSL; there was no Disability Discrimination Act – so all of these things were perfectly legal.

And so, I’d like to finish by talking about two of the most recent developments that are changing that picture from 50 years ago. The first is the BSL Act 2022, in which British Sign Language was recognised as a language of England, Wales and Scotland. The Act states, among other stipulations, that the Secretary of State must provide guidance about the promotion and facilitation of the use of BSL, including advice for relevant government departments; advice on best practice for communicating with British Sign Language users (both when interacting with individuals and when communicating with the public at large), and government departments are required to report on how they are promoting and facilitating the use of BSL.

In parallel with the passing of the Act, the Department of Education had begun work in 2018 on the development of a GCSE in BSL. I served as one of three members of the Working Group charged with developing the curriculum and course content. Consultations went out last summer in 2023, and the GCSE has been approved by the Minister and is due to launch in autumn 2025, sitting alongside other modern languages as an option for both hearing and deaf students. It is too early to assess the take-up of BSL as a GCSE subject, but it's expected to be a popular choice, and we plan to undertake research on the teaching and learning of BSL as a second language in schools once the course is underway.

Deaf boy using sign language with teacher
Deaf child using sign language with teacher. Image credit: Brian Mitchell via Getty Images

So what does the future hold? I spoke in a podcast two years ago about both positive and negative pressures on BSL. On the one hand, there’s been a decrease in opportunities for deaf children to use sign language with other deaf children because of the shift to mainstream education where there may be only one deaf child in a school who must interact via an interpreter or communication support worker. At the same time, there’s been a great deal of increased interest from the public in BSL and the deaf community, with deaf contestants on Strictly Come Dancing and The Great British Bake Off and much increased visibility of BSL in public contexts, including provision of BSL-English interpreting on broadcast media and on the internet. All these have increased demand from the hearing community to study BSL. And the positive attitudes of the hearing community have increased the pride of the deaf community in their distinctive language and culture. It's to be hoped and expected that sign languages will continue to be living languages into the future.

Bencie Woll FBA is Professor of Sign Language and Deaf Studies at University College London   

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