If a person is born deaf, ever wondered what language the concerned person is going to pick for thinking? This is actually a pretty good question and mystery to solve. Andrew McKenzie, who holds Ph.D. in Linguistics from the University of Kansas situated in the United States of America tells that it depends on the considering factors which have usually some connection to consciousness.[irp]
Internal monologue is also not something which infants can immediately do straight away. The thing is that basically the affected person learns through experiences and gains knowledge with the passage of time. Therefore, it really depends on what language the concerned person picks or learns.
Usually, a person who is congenitally deaf might have a Cochlear implant. A cochlear implant is an electronic medical device whose work is to replace the job of the damaged inner ear. So, the person who is fitted with a Cochlear implant can learn to speak English which might even be fluent or any other language being spoken around that person. This is the case where the deaf person probably can think.
This should be obviously better than growing up in a Deaf community and picking a sign language. In this case, there's no justification to assume that the person won’t just think effectively in sign language as a normal person thinks in words because this is the norm.
Such kind of people can also have a cochlear implant but still, they are growing up in a Deaf community and learning sign language. They are intended to think in both languages which is pretty much like any other bilingual language but still, it depends upon the condition.
Things might also change with time and the situation can reverse as well. That’s really unfortunate for someone to be born deaf and not having a facility or access to cochlear implants but still, the worst thing is that they also don’t have access to a Deaf signs community. This way the person has no language to think in. In this case, they often develop their self-specific home sign or kitchen sign.
Home sign or kitchen sign is primarily a gestural communication system which can be developed by a deaf child who lacks input of a language. This is the closest approach to have a language system and it's the same for them as they do much of their thinking by using their own internal version of home signs. Therefore, it is quite possible that their thinking is more conceptual as compared to symbolically mediate.
Sometimes a person is not born deaf but has damaged vocal chords due to some tragedy or surgery which makes him unable to produce sound. It is also experienced that people who use signs for expressing their language can also think in sign language.
Besides this, it is important to note that not all the thinking is compulsory linguistic but still it really depends on the way you get the mean of thinking. However, some thought processes could vary with conditions and situations as for whether they've had Cochlear implant, use sign, both or sometimes nothing.