Inner Speech

Inner speech, the experience of talking to oneself in the mind, is one of the most commonly experienced yet least scientifically understood mental activities.

For example, when you mind wanders off in a lecture, you may hear yourself say: “Hmm… What shall I have for lunch?” or “Gosh! This lecture is really boring!”. When you try to remember a phone number, you rehearse the digits “071234…” in your mind until you write it down.

In a nutshell, I’d like to think inner speech as conscious expressions of linguistically structured thoughts. Research on inner speech is quite limited, in both scope and methods. The reality is that inner speech takes many different forms and is likely supported by multiple mechanisms. In our lab, we are particularly interested in how inner speech’s diverse phenomenology (e.g., dialogic/monologic, intentional/spontaneous) is supported by neurocognitive mechanisms of the brain. Our current model involves a dual-stream mechanism where the phenomenological variety of inner speech are jointly supported by a mechanism based on corollary discharge and a mechanism based on perceptual simulation (re-activation of sensory experience). We use a combination of fMRI, EEG to characterise the neurophysiological signatures of inner speech in various task conditions, and use neurostimulation to examine its functional roles in cognition and consciousness, within and between individuals.

Studying inner speech is very interesting because it is a very intimate experience shared by most of us. It is also very challenging because it is too private to be directly observed by researchers. There are some crazy questions you can ask about inner speech, e.g.:

  • Do deaf people hear inner speech? (Apparantly they say they do - even for congenitally deaf individuals)

  • If they do, what is the nature / representation of their inner speech (perhaps inner speech is not so much about the sound)?

  • Does sutterers’ inner speech stutter?

  • Why do we need inner speech? Why is it there? (hard question! and apparently some people don’t have inner speech - you may be surprised - and how does their brain work then?)

The list is endless…

So if this has not piqued your interest, I don’t know what will. Please get in touch and let’s do something interesting :)

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Example Papers:

(2021). Reading direct speech quotes increases theta phase-locking: Evidence for cortical tracking of inner speech?. NeuroImage, 239, 118313.


(2020). Processing speech and thoughts during silent reading: Direct reference effects for speech by fictional characters in voice-selective auditory cortex and a Theory-of-Mind network. Journal of Cognitive Neuroscience, 32(9), 1637-1653.


(2015). Inner voice experiences during processing of direct and indirect speech. in Frazier, L., & Gibson, E. (Ed.), Explicit and Implicit Prosody in Sentence Processing (pp. 287-307). Springer..


(2011). Contextual modulation of reading rate for direct versus indirect speech quotations. Cognition, 121(3), 447-453.


(2011). Silent reading of direct versus indirect speech activates voice-selective areas in the auditory cortex. Journal of Cognitive Neuroscience, 23(10), 3146-3152.


Bo Yao
Bo Yao
Cognitive Neuroscientist

Cognitive Neuroscience of Language