Child language acquisition research on indigenous African sign languages: A commentary on Kidd and Garcia (2022)

It is not always the case that an endangered language goes through a revitalisation programme. For most endangered languages, there are no attempts for revitalisation. More alarming is the case of endangered languages without any documentation. This is the case of many indigenous sign languages around the world. For such languages, we may never hear of them, nor understand their child language acquisition process. Currently, our understanding of sign language acquisition by children is framed by the research on the few sign languages that have child language acquisition projects. There is a dearth of research on child language acquisition for indigenous African languages, and for indigenous African sign languages, there seems to be no documented research on child language acquisition.

Sign languages have been used on the African continent for millennia. For example, the theologian Augustine (354-430) from what is now Algeria documented gestural communication involving deaf people in Africa (Miles, 2005). Although linguistic research on sign languages began in earnest in the 1960s when Stokoe published his monograph on American Sign Language (ASL; Stokoe, 1960), sign language research in Africa is still minimal as compared to the research done on spoken African languages. In fact, there are more undocumented sign languages in Africa as compared to documented sign languages, and intense research on indigenous African sign languages began at the end of the twentieth century with the detailed linguistic documentation of Hausa Sign Language (Schmaling, 1997). Most indigenous sign languages in Africa are yet to be documented, linguistic descriptions are yet to be developed, and sign language linguistics is still a novel field in most African nations.

Research on typologically diverse languages of the world is relevant to test the different theories of language including acquisition. Our understanding of sign language acquisition has been framed based on research on ASL, British Sign Language and few other sign languages used in Europe, America and Asia, as identified in Kidd and Garcia’s (2022) survey. Research on different African sign languages has revealed typological differences between different sign languages classified as urban and rural sign languages (Asonye et al., 2018; Edward, 2021). Urban sign languages refer to national sign languages and sign languages of education, while rural sign languages refer to sign languages that are used in communities with high incidences of genetic deafness and are typically used for communication between deaf people and between deaf and hearing people. For example, whereas most urban sign languages in West Africa have had internal and external influences from ASL, the rural sign languages are mostly indigenous African sign languages. The influence of ASL in the structure and grammar of many African sign languages can be attributed to the missionary work of Dr Andrew Foster, a deaf African American missionary who established 31 schools for the Deaf across Africa, trained deaf leaders, and introduced Total Communication, which embraced both American and indigenous signs (Kiyaga & Moores, 2003). Undoubtedly, urban and rural sign languages in Africa have linguistic and sociolinguistic purviews that bring about differences and similarities between them. For example, indigenous African sign languages have differential features such as the use of the legs as active articulators and the use of a larger signing space as compared to the urban sign languages. One major sociolinguistic difference between urban and rural sign languages is the size of the signing community; urban sign languages have quite large communities of use (mainly deaf individuals) compared to rural sign languages that are used in small communities and acquired as L1 by both deaf and hearing individuals. Therefore, without understanding the language acquisition process of indigenous African sign languages, we will not have a full understanding about sign language acquisition: we cannot make generalisations across all sign languages because of their typological differences.

Recent research on child language acquisition in spoken African languages such as Akan (Amoako et al., 2020; Amoako & Stemberger, in press) has given new perspectives in the field of child language acquisition. For example, although it has been reported that vowels and tones develop early in languages, the acquisition of vowels in Akan ‘is not complete till age five, and errors in tone productions are observed even at age five’ (Amoako & Stemberger, in press) pointing to the effects of language-specific complexities in phonological development. This finding from Akan challenges theories of children’s phonological acquisition in spoken languages and provides an avenue for future research. Will research on children’s acquisition of indigenous African sign languages influence theories about language acquisition? Research on different rural/indigenous sign languages have identified specific representations of linguistic features such as number, kinship and colour, negation, use of space, classifiers (De Vos & Pfau, 2015; Edward, 2021; Nyst, 2007; Zeshan, 2006). For example, whereas the use of entity classifiers for motion and location has been identified in several languages, Nyst (2007) identified that the signers of Adamorobe Sign Language (AdaSL), an indigenous sign language of Adamorobe (Ghana), do not use entity classifiers to express motion and location. A few years after Nyst’s research, Edward (2021) identified that the older signers of Adamorobe are gradually introducing entity classifiers for motion events. However, we are unable to compare if similar acquisition patterns exist among children using AdaSL as their first language since there has been no research on AdaSL acquisition.

Furthermore, we might never be able to reconstruct the child language acquisition patterns for indigenous sign languages without younger signers. Many indigenous African sign languages are moribund, and few others are already endangered. For example, Asonye and Akpan (forthcoming) identified the scarcity of younger signers of Magajin Gari Sign Language (MGSL) used in Kaduna North (Nigeria). The authors stated that the youngest of the signers were in their 30s and there was no child identified to be using MGSL. Will the acquisition of indigenous African sign languages follow the same pattern as has been found in the West? This question can be best answered with examples from the different indigenous African sign languages. Therefore, it is imperative to undertake research on child language acquisition on indigenous African sign languages while there are still child signers.

African communities are mostly multilingual, and this affects the signing communities. Most Deaf signers from Africa are either unimodal multilinguals with knowledge of different sign languages or bimodal multilinguals with knowledge of different signed and spoken languages, and these linguistic repertoires have different acquisition patterns. For example, in the Adamorobe Deaf community in Ghana, different linguistic repertoires have been documented. Whereas AdaSL and Akan (spoken) have been identified as the L1 of deaf children, Ghanaian Sign Language (GhSL) and English are the L2 of deaf children who are currently in school (Edward, forthcoming). How is the acquisition of AdaSL different from GhSL? Does the acquisition of English follow the same pattern as the acquisition of Akan? Given what we know about their linguistic features, we can hypothesise similarities and differences in the acquisition patterns for AdaSL and GhSL, but we do not have empirical evidence on how similar or different the patterns are. In order to improve language coverage, there is a need to diversify the field as this will develop a more inclusive research community and enable comparison between languages. Furthermore, diversifying research on child language acquisition and focusing on indigenous African languages will contribute to making language theories that are applicable to monolingual and multilingual Deaf communities.