To the editors:
In her essay, Iris Berent criticizes Friedemann Pulvermüller et al. for repeating a claim about human language that has been made many times before: knowing and using a language is having the ability to speak it.1 In response, she cites her own work as well as that of others.2 These studies concerning the perception of sign language phonology found stimulation in areas of the brain related to the production of these units.3 Their authors claim that speech and sign both draw from similar areas of the brain, as has been shown in studies of perception and production of language stimuli. More broadly, Berent describes language as amodal, and that while often expressed in speech, language is not restricted to that modality alone.
The persistence of the claim that language exclusively, or even largely, involves speech comes from a common-sense observation. Because so many human communities around the world use speech, speech must therefore be the basis for language. It follows then that people who use sign language instead of speech have a disability. They cannot access speech, nor can they use it. This point is driven home by the use of the category of deaf sign languages in language databases.4 Although such a category recognizes deaf communities and their history of sign languages, it also suggests that without deaf people, there would be no sign language. As a thought exercise, try to imagine blind languages or brown languages. Clearly, neither of these categories exist, but the presence of a deaf sign languages category suggests that languages can indeed exist as a result of a physical characteristic. What then is the relationship between deafness and the biological basis of language?
Sign languages and signers are more numerous than many scientists and the general public realize.5 A common misconception is that only deaf people use sign language. Deaf parents with hearing children rear them as bilingual in a spoken and sign language. Deaf people often have hearing siblings who grow up with them also using sign language. Each year, new sign languages are discovered and added to language databases. The new languages originate in widely dispersed locations, such as Papua New Guinea, Mali, Rwanda, and Iceland.6 Every continent, except perhaps Antarctica, has communities of people who sign. Some are very small, encompassing a single family or a group of families.7 Elsewhere, sign language is used by communities of both hearing and deaf people as a village-wide language in addition to the spoken language. The largest signing communities are those that share a national sign language. American Sign Language (ASL) has an estimated 500,000 primary users in the US and Canada.8 The primary users of India-Pakistani Sign Language are more numerous, estimated at close to 6,000,000 users.9 Indeed, some sign language communities are far greater in size than the number of people using the world’s least-spoken languages, such as Basque or Tzotzil.10
People who sign in addition to speaking are also easily overlooked. The modality in sign language is used by people who are not speech disabled, but abide by speech-related taboos,11 such as the Warlpiri in Central Australia. These sign languages are termed alternate languages because the spoken language remains primary in these communities. Nonetheless, the usage of signing in these communities belies the simple relationship of deafness to language. Deafness does not directly describe the biological basis of human language in these different forms, nor in these different communities. Thinking of sign languages only in terms of who uses them can be deceptive. The real task at hand is to understand human languages across the wide span of people who use them.
Berent describes a recent study that involved asking naive hearing speakers to consider a pair of signs that they have never seen before and report which sign seems more appropriate to a given morphological form, such as plural. The study showed that speakers of languages with plural morphology consistently choose the same sign from the pair if the same morphology is present in the speaker’s language. If the language used by the speaker does not mark plurals, as in Chinese, there is no consistent preference for one sign over the other. In her essay, Berent describes language as “an abstract algebraic system that can emerge in either system.”
Although Pulvermüller et al. do not explicitly state that language is only speech, the implication in their work is clear. The world is made up of an overwhelming number of speaking communities and speakers. Why would a scientist need to account for both speech and sign when one type outnumbers the other? One reason is that many families who discover that their child is deaf will delay learning a sign language in the hope that the child learns speech first. The belief that speech is primary has led to education policies in many countries that penalize sign language learning. These policies have come at great cost both to individuals and—as my colleagues and I have argued12—to wider society. The human brain is not only uniquely suited to language, it is also uniquely flexible to language. Investing in theory building that accounts for the ways that humans use language around the world, from spoken languages with clicks or tones to sign languages for different communities of users, conveys a richer understanding of the human brain. Berent does her field a service in calling for a science of language that is broad and inclusive, in order to enrich both science and its allied fields in medicine, child development, and education.
Carol Padden
Iris Berent replies:
In their letters, Carol Padden and Michael Corballis raise interesting questions regarding the equipotentiality of the language faculty with respect to its channels—speech and sign—and their roles in language evolution. In this brief commentary, I will not engage with their arguments but only offer some clarifications concerning the target piece.
To set the record straight: my reference to Noam Chomsky’s position as a minority view is strictly a descriptive observation. Much to my chagrin, Chomsky’s account of language is not broadly subscribed to in cognitive science. But scientific merit is not a popularity contest—or certainly not a short-term one. Over the long run, it has been Chomsky’s research program that has founded cognitive science and shaped its research agenda ever since. In my mind, there is no question that, just as Corballis suggests, Chomsky commands the utmost respect.
While Chomsky’s own discussion of I-language has indeed focused mostly on syntax, nothing in his framework precludes the possibility that some aspects of phonology could feature into I-language, including Universal Grammar. The algebraic amodal view of phonology I endorse is entirely in line with Chomsky’s generative tradition.
Whether this hypothesis is correct is, of course, an open empirical question. Considerations of language evolution can inform this discussion. But it is difficult to evaluate evolutionary proposals, such as the one advocated by Corballis, unless linguists can accurately characterize the present state of the language faculty. If we don’t know what language is, how can we tell how it has become?
Addressing this question requires that we combine insights from linguistic analysis, experimental investigations, and computational work. And as Padden suggests, our approach ought to be broad and inclusive. The various individuals who have responded to my piece—Padden, Corballis, and Mark Aronoff et al.—are known experts in these disciplines, and I am grateful for their comments. I hope this discussion revitalizes research efforts into the design of the language faculty in all its forms.
