In blindsight you lose the conscious experience of vision due to loss of the visual cortex, but you retain the ability to respond to visual information (due to intact subcortical visual processing). You don’t think you can see, you have no experience of ‘seeing’, but you can make rudimentary visually guided behaviours. I’ve been told that the experience is a lot like being able to make guesses which feel completely uninformed but are startlingly accurate.

Parallel to visual processing, auditory processing is also done subcortically and cortically (replace ‘visual cortex’ with ‘auditory cortex’, replace ‘superiour colliculus’ with ‘inferior colliculus’). I’m sure the correspondence isn’t exact, but how’s this for a prediction: deafhearing – following loss of auditory cortex the conscious experience of sound would be lost, but the ability to make responses based on noises would be retained due to intact subcortical auditory processing.

I haven’t trawled the annals of neuropsychology to see if this condition has ever been documented – and Iโ€šร„รดm not going to just yet since I prefer to sit here and speculate! – but I think it is strong possibility.

(interesting tangent: the link above, and here, draws out the parallel between blindsight and normal ‘intuition’ where we are required to make choices before all the (sensory) evidence is in)

5 thoughts on “Deafhearing”

  1. I’ve experienced ‘blindsight’ before on LSD. It’s extremely disconcerting. I was unable to see, but would flinch from movement. It was a little bit like my entire field of vision became peripheral vision. The experience was scary enough to discourage me from taking LSD again.

  2. Your intuition on deaf hearing was correct: Garde MM, Cowey A (2000) “Deaf hearing”: unacknowledged detection of auditory stimuli in a patient with cerebral deafness. Cortex 36(1): 71-80

  3. Excellent, thanks prd – very satisfying to know.
    My next predictions is that there should be no equivalent phenomenon for smell, because smell information enters the cortex directory (at the olfactory bulb) without any pre-thalamic/sub-cortical processing ๐Ÿ™‚

  4. I have been ‘blindsighted’ in my right eye, and I believe, deaf-hearing in my right ear since birth. Here’s a poser for you… I am conscious of ‘musical’ sound from around middle C and below in my right ear (verified by an audiologist). However, spoken language is gibberish on that side. My doctor presumed this was because of a lack of higher-pitched consonant sounds. But one night, wilst my left ear was buried in a pillow, I found I could understand words (a radio newscast) with my right ear if I maintained a meditative enough state of mind. It is still very difficult to do this for very long. There doesn’t seem to be a lasting benefit. Although it has become slightly easier to do with age and/or practice. Any theories?

  5. It could be the brain is capable of getting information from one sense and interpreting it with another (like in synaesthesia). Could information from the skin (able to detect light and vibrations) feed into the visual/audio cortexes? —
    Then there are theories that the universe (including people) is layered system: if a component breaks down on one level could another act as a replacement?—
    Or if the entire physical universe is nothing but a construct of the mind, there should be mental tricks that allow one to change what is [real], as with levitation, faith healing, etc.

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