Hello I’m Simon Whistler, you’re watching the Today I Found Out YouTube channel, and
in the video today if you’ve ever wondered how deaf people think, in terms of their inner
voice, well, you’re not going to wonder for much longer.
Those who were born completely deaf and only learned sign language will, not surprisingly,
think in sign language.
What is surprising is those who were born completely deaf but learn to speak through
vocal training will occasionally think not only in the particular sign language that
they know, but also will sometimes think in the vocal language they learned, with their
brains coming up with how the vocal language sounds.
Primarily though, most completely deaf people think in sign language.
Similar to how an "inner voice" of a hearing person is experienced in one's own voice,
a completely deaf person sees or, more aptly, feels themselves signing in their head as
they "talk" in their heads.
For those deaf people who are not completely deaf or wear devices to allow them to hear
somewhat, they will often experience more vocal language in their "inner voice" in proportion
to how much they can hear.
Interestingly, deafness is significantly more serious than blindness in terms of the effect
it can have on the brain.
This isn't because deaf people's brains are different than hearing people, in terms of
mental capacity or the like; rather, it is because of how integral language is to how
our brain functions.
To be clear, "language" here not only refers to spoken languages, but also to sign language.
It is simply important that the brain have some form of complex language it can fully
comprehend and can turn into an inner voice to drive thought.
More specifically, language is integral in such brain functions as memory, abstract thinking,
and, fascinatingly, self-awareness.
Language has been shown to literally be the "device driver", so to speak, that drives
much of the brain's core "hardware".
Thus, deaf people who aren't identified as such very young or that live in places where
they aren't able to be taught sign language, will usually be significantly handicapped
mentally until they learn a structured language, even though there is nothing actually wrong
with their brains.
The problem is even more severe than it may appear at first because of how important language
is to the early stages of development of the brain.
Those completely deaf people who are taught no sign language until later life will often
have learning problems that stick with them throughout their lives, even after they have
eventually learned a particular sign language.
It is because of how integral language is to how our brains develop and function that
deaf people were long thought of as inherently mentally handicapped and unteachable.
In fact, until around the 1970s, it was still widely thought that the majority of deaf people
were at least mildly mentally handicapped.
How could this be when they had various sign languages and even vocal training to allow
their brains to develop and function properly?
The problem stemmed from the fact that it was decided at the International Congress
on Education of the Deaf that took place in 1880 in Milan that deaf people should not
use sign language; rather, they should be forced to use spoken language almost exclusively.
This seems reasonable enough on the surface, as deaf people are fully capable of learning
spoken language and this would allow them to more completely integrate into the hearing
world, which is what spurred these educators to make this momentous decision.
The problem with this was only recently discovered and, indeed, many of the negative implications
are only just now being understood.
It turns out, while there are certainly exceptions, most completely deaf people who are forced
to use only spoken language are only slightly better off than those who know no language,
in terms of the development of certain brain functions.
The first research showing the failure of the oral method was done by Cambridge Professor
Ruban Conrad in the 1970s via testing reading ability in deaf teenagers trained in said
method.
He discovered that while the average fully deaf teenager could read individual words
at about an eight year old level, they read without much understanding, particularly when
it came to taking in the meaning of a full sentence.
The problem was that they had not adequately been able to develop an "inner voice" due
to being restricted to oral language which they could not hear.
Thus, without the inner voice, there was no auditory imagery to linger in short term memory
while they took in the whole sentence.
In the general case, the fully deaf taught only the oral method do gain significantly
more sense of self and better memory and the like over those who have no language at all,
but in this state, they will never fully reach their brain's potential as in when they learn
sign language.
The leading theory behind why those completely deaf people taught only vocal language don't
properly develop an "inner voice" is that, without being able to associate sounds with
the phonemes and complete words, the language is too abstract and a brain without language
already struggles with things that are abstract.
Those deaf people who learn sign language, however, have less trouble with comprehending
vocal language and, as noted earlier, have the ability to have an "inner voice" that
speaks.
This is thought to be because, once the brain has a structured language from which to more
or less "run" off of, similar to a computer’s operating system, abstract concepts can be
more easily grasped; thus, comprehending vocal language sounds and text becomes significantly
easier.
Because of these findings, the "oralist" method of teaching the deaf that had endured for
just under a century began being rapidly phased out in favor of a "bilingual" education where
sign language is taught as early as possible and vocal language is taught as a sort of
secondary language.
As noted by Miranda Pickersgill, chief of deaf services for Leeds Local Education Authority,
"Bilingualism is still very much a hot potato.
We have come in for a lot of flak and been accused of pushing deaf children into a signing
ghetto.
Yet the deaf had a big price to pay when the old methods failed.
Not only could they not communicate, but they were left without a code to think in.
We can no longer ignore what the research tells us."