Sign Language

Gestures offer a way to communicate in situations where spoken language cannot be used (e.g. for deaf people). There are various ways in which gestures may be used:

• finger spelling uses hand-shapes to represent individual letters. This has the advantages of being relatively easy to learn, and very flexible: when you come across a new word, you don't need to invent a new sign for it, you just spell it out. On the other hand, it can be slow and laborious to use, and relies on knowledge of an underlying language that you know how to spell. So it's not much use for young children, for example.
• cued speech is a way of making it easier for someone to lip-read: for words which have imprecise lip movements, the hand can be placed in different positions to indicate more precisely what's being said. Cued speech, like finger spelling, relies on knowledge of an existing language
• language-based sign systems use signs to represent grammatical constructs (e.g. a flick of the finger may indicate the suffix "-ing"), and reflect the order of language as it would be spoken. These are intended as a temporary help for people who are expected to be able to learn to use language normally, a bit like stabilisers on a bicycle. Examples of these are Signing Exact English (SEE) and the Paget-Gorman Sign System (PGSS). See Crystal ch.37
• Autonomous sign languages, such as BSL and ASL are complete languages in themselves, and are not built on any underlying spoken language.

• There is no "universal" sign language: people who know one sign language (e.g. ASL) have the same chance of understanding another (e.g. BSL) as a speaker of one language would have of understanding a different spoken language.
• corresponding to phonemes in spoken language, sign languages can be seen to be made up of fundamental cheremes, which are put together to convey a meaning. Not all sign languages use all cheremes
• signs for words are discrete: there may be a sign for "bat" and one for "ball", but there's no intermediate sign that means a bit of both
• signs are arbitrary: in most cases a non-signer couldn't guess the meaning of a sign by what it looked like
• signs are dual-patterned: the same cheremes can combine in different ways to represent up different concepts
• sign languages develop dialects
• Whereas spoken language uses words to signify tense and "joining" words such as "the" etc., these modulations of meaning are typically conveyed in sign language using facial expression and other body posture etc., in addition to the hand gestures
• A literal transcription into English of a sentence signed in BSL may sound primitive, e.g. "you me downtown movie go fun?" but this in not because BSL is less sophisticated, more that the transcription has failed to capture the facial expressions and nuances of gesture which provide context to the statement

Teaching Language to Chimps

Early attempts that were made to try and teach chimps to speak were not very successful: the vocal tract of the chimp is not physically capable of articulating the range of sounds necessary for human-type speech. Later researchers have concentrated on teaching chimps some form of sign language.

There have been some notable experiments (see Fromkin p384 for a list of chimps), and in some cases it has appeared that chimps have been able to learn upwards of 300 "words", responding to questions posed by humans by performing actions, or "replying" using the sign language they've been taught.

Unfortunately, there has been doubt cast on many of these experiments, in large part because of the lack of rigour under which they were carried out, and the seeming over-optimism of the researchers in reporting successful "sentences" constructed by the chimps.

It seems likely that what the chimps are displaying is more of a performing trick - they have learnt that by making the signs that represent "chimp" and "banana", they get given a banana - than evidence of linguistic ability. In any event, they don't appear to be able to cope with the same level of linguistic ability as is displayed by a three year old child, no matter how much training they get. And it should be pointed out that a three year old child doesn't need to be "trained", he just picks up language.