Neuroscience: Listening in on yourself

Journal name:
Nature
Volume:
532,
Pages:
32–33
Date published:
DOI:
doi:10.1038/532032a
Published online

Douwe Draaisma is intrigued by a study examining both 'the voice within' and verbal auditory hallucinations.

The Voices Within: The History and Science of How We Talk to Ourselves

Charles Fernyhough Profile: 2016. ISBN: 9781781252796

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Illustration by Rebekka Dunlap

Thinking about thinking is a curious exercise. Most of us probably agree that much of our own thought process takes the form of inner speech. But would we also agree that we hear an inner voice? If not, why would we call it talking at all? Can we experience and observe inner speech simultaneously, or would this be like “trying to turn up the gas quickly enough to see how the darkness looks”, as US psychologist William James asked himself in 1890? Each of these questions may lead one into a philosophical forest, dense and dark.

“Silent self-talk turns out to be a robust part of memory.”

Side-stepping such conceptual intricacies, psychologist Charles Fernyhough convincingly explores inner speech from a practical perspective. In The Voices Within, he discusses how people with aphasia (a speech and language disorder that stems from brain damage) may lose their sense of inner speech; how deaf people 'talk to themselves' (mostly in sign language, some by lipreading); how more than 60% of children have had silent conversations with imaginary friends; and whether people who stutter experience their inner speech as fluent (they do). Silent self-talk, evasive as it is to introspection, turns out to be a robust and quintessential part of memory, thought and imagination.

Fernyhough's sources are equally wide-ranging. He draws on internal monologues in Gustave Flaubert's 1856 novel Madame Bovary and reports of self-talk by professional cricketers. He mentions physicist Richard Feynman having an argument with himself, and Joan of Arc insisting that God talked to her in French, not Latin. Today, Fernyhough directs Hearing the Voice, a research project at Durham University, UK, funded by biomedical charity the Wellcome Trust.

When I'm invited to write a review, I know from experience that it is wise to switch my inner speech from Dutch, my native language, to English, which I routinely use for scientific communication. Most bilingual people have no trouble identifying the language that they are thinking in. But I would be hard-pressed to say whether I talk to myself at a natural speed or in an abbreviated way, much less whether the stream of my thoughts flows equally fast (or slow) in both languages. Most people say that they have the definite impression that their inner speech unfolds faster than actual speech.

Referring to the ideas of philosopher Eric Schwitzgebel, Fernyhough points out that this leaves several questions open. Is internal speech faster because it is unhampered by slower motor processes, or because we don't think in full sentences? According to twentieth-century Russian psychologist Lev Vygotsky, inner speech develops as children's conversations 'go underground', often as a result of social encouragement. In the process, they begin to think in 'pure meanings', causing telegraphic inner speech. This condensation, in turn, could help to explain the paradoxical sensation that inner speech feels faster, but never rushed. Sped up or condensed? To this day, there are no consensual methods or techniques to decide between the two.

Fernyhough also presents several interviews with participants in his Durham research project, itself an offshoot of the Hearing Voices Movement founded in 1987 by Dutch psychiatrist Marius Romme and now expanded to 23 countries. At present, the United Kingdom has 180 support groups for voice-hearers. Some people report hearing intrusive voices, often whispering or shouting abuse, and seek relief by joining a local group. Most people who experience verbal auditory hallucinations have had a diagnosis of schizophrenia or have experienced childhood abuse — but, as Fernyhough points out, not all. Clinically relevant as they are, these chapters expose a tension in The Voices Within: it is still a matter of controversy whether hearing voices has much to do with the quiet self-talk of ordinary thinking.

Fernyhough tries to bridge this gap with a model that he dubs dialogic thinking, which conceptualizes inner speech as an internalized conversation between different voices. He hypothesizes that if a patient fails to identify a particular utterance as a fragment of some inner dispute, he might experience this fragment as coming from an external source — a hallucination. But many voice-hearers also experience inner speech, and can distinguish between the two. It remains to be seen whether the experience of hearing voices will really offer a window on inner speech.

We have come a long way from US psychologist John Watson's behaviourist speculation that inner speech is simply covert motor action in the speech apparatus. New methods have invited new distinctions. Neuroimaging studies by Fernyhough and his colleagues suggest that speaking internally when instructed activates Broca's area in the brain (associated with producing speech), and de-activates Heschl's gyrus (associated with auditory perception). Spontaneous, free-flowing inner speech, on the other hand, involved the opposite pattern of neural activation. This is but one of many promising avenues of research, and The Voices Within is full of them. Profound and eloquent (he is a novelist too), Fernyhough presents an intriguing array of fresh findings and perspectives. He makes a persuasive case that one of the most intimate and private of our mental activities has a social origin. We talk to ourselves because we talked to others first.

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  1. Douwe Draaisma is professor of the history of psychology at the University of Groningen in the Netherlands. His latest book is Forgetting.

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