An interesting thread on Quora asks "Does someone who was born with a hearing loss "hear" an inner voice?" Several people who have experienced hearing loss have contributed to the discussion, and their responses make for fascinating reading.

First, why is the question of interest? As I mentioned in my last post, researchers are approaching the phenomenon of inner speech, or the "voice in the head," with renewed vigor. Inner speech seems to be a common phenomenon, and it has been associated with a number of important functions, from controlling one's own behavior to developing a sense of self.

What's more, one developmental view of inner speech sees it as emerging from social interactions that are mediated by spoken language. What's the story, then, for someone who doesn't use spoken language? Is there a kind of "inner sign" that does all the things that spoken inner speech seems to do?

A number of the Deaf respondents to the Quora question suggest that this is indeed the case. One participant states, "I have a 'voice' in my head, but it is not sound-based. I am a visual being, so in my head, I either see ASL [American Sign Language] signs, or pictures, or sometimes printed words." For this respondent, sound is not a feature of the experience. Another respondent experiences a mix of modalities: "[M]y is figuratively speaking to me and I hear it as well as lipread it." In this case, the experience has both auditory and visual properties.

The age at which hearing loss happens is likely to be important in determining the modality of inner speech/sign. One participant who lost his hearing at age 2 says he thinks in words, but words without sound, while another individual with early hearing loss describes "hearing" a voice in in the absence of signs or lip movements.

What does it mean to hear a "voice" when the experience doesn't seem to have any sound attending it? One way of thinking about this question is to ask about the properties of inner speech reported by hearing people. According to Vygotsky's theory, the process of internalization of linguistic exchanges results in many of the acoustic properties of language being stripped away, resulting in what I have termed "condensed inner speech." Arguably, condensed inner speech sounds like a voice, but a voice with nothing very "speechy" about it.

Several studies have shed light on how individuals with hearing loss use inner sign. There is evidence that inner sign mediates short-term memory in signing individuals, just as inner speech mediates short-term remembering in hearing people. In a neuroimaging study, areas of the brain associated with inner speech were activated when signers thought to themselves in sign, suggesting a common pathway to thinking in language that is independent of the modality of that language.

Private and inner signing seem to be of potential benefit to hearing people as well. One (hearing) researcher on the Quora forum reports that private signing helps her sometimes to find English words, and that inner sign can even enter her dreams after she has been interacting with other signers.

This topic has been very much on my mind since a fascinating talk given to our Hearing the Voice project by Dr. Joanna Atkinson of the Deafness Cognition and Language Research Centre at University College London. Jo's work has looked at the experience of voice-hearing among those with hearing loss, and I'll be writing about it in a future post. If some voice-hearing experiences involve the misattribution of inner speech, can something similar happen with inner sign?

Thanks to Jad Abumrad for drawing my to the Quora discussion.