Answer 1 :
For pre-lingually deaf people who are neither exposed to nor allowed to communicate in a sign language, this is a very serious concern. It seems that the development of language allows humans not only to discuss, but also to conceptualise abstract ideas.
Many deaf children in the past were assumed to have an intellectual disability, but the problem evaporated once they were given access to language via signing. For those deaf people who do learn sign, sign languages seem to function just as any aural language does, the only difference being the channel used for communication.
Those who learn to sign as a first language will think in it as well, even if they go on learn other languages, as is the case in hearing children of deaf parents. This is not such a strange idea — very few hearing people would claim to actually hear voices when they are thinking.
However, the signers develop slightly faster, probably because speech requires complex motor movements while sign languages use very precise hand signals.
Contrary to popular belief, sign language is not merely a visual from of English, as English is spoken.
It is actually a language in its own right, and in the U.S, American Sign Language (Ameslan) is much closer to spoken French than it is to English, thanks to its separate development.
Recent research has produced reliable evidence of thought in babies, who obviously cannot think in words.
Much adult thought, particularly abstract theoretical speculation, is language-based, and some is conditioned by the constraints of the language we know, but the idea that it is always so (known as the Sapir-whorf hypothesis) is now thoroughly discredited.
Non-linguistic thought is more frequent than one might expect. However, any attempts to reflect on it inevitably involve language, the normal form of abstract thought.
Because both this reflective process and the non-verbal thinking which is its object occur in the mind, it is easy to merge one with the other and ignore the wordlessness of much thinking.
Hence the Sapir-Wharf, hypothesis, and the consequent prejudice that dumb animals lack consciousness.
Non-verbal thought consists of the logically integrated structuring of proprioception — awareness of the body's posture and of the response to external and internal stimuli by its sense organs — and the recollection and projection of visual images, emotions and sense data.
Worldless thought is clearly the norm for animals, much of whose behaviour cannot be explained without assuming they are capable of elaborate thought processes such as anticipation, correlation and deduction. Even a humble squid has enough cognitive ability not to eat itself.
Source : The Hindu