Developing an electrophysiological marker of inner speech

What is this research about?

Inner speech – also known as imagined speech, covert speech, or verbal thoughts – refers to the act of silently producing words in our minds. It is one of the most ubiquitous human activities; it has been estimated that most people spend at least a quarter of their lives engaged in inner speech.

The primary aim of this project is to develop an objective, electrophysiological marker of inner speech. The key idea behind this goal is that the content of a person’s inner speech should influence their electroencephalographic (EEG) activity evoked by audible sounds.

By developing an objective marker for inner speech, this project will shed light on the neurophysiological underpinnings of a purely mental process. Furthermore, it may have important implications for understanding why people with mental illnesses, such as schizophrenia, sometimes experience auditory-verbal hallucinations (i.e., ‘hearing voices’). The development of an objective marker would allow us to test the long-held but hitherto-untestable assumption that auditory-verbal hallucinations are caused by an inner-speech abnormality. 

Other researchers working on the project
  • A/Prof. Mike Le Pelley
  • Dr. Bradley Jack
  • Mr. Daniel Pearson
  • Dr. Oren Griffiths
  • Dr. David Luque (University of Malaga, Spain)
  • A/Prof. Anthony Harris (University of Sydney)
  • A/Prof. Kevin Spencer (Harvard University)
Publications relating to this project
  • Whitford TJ, Jack BN, Pearson D, Griffiths O, Luque D, Harris AWF, Spencer KM, Le Pelley ME. (2017). Neurophysiological evidence of efference copies to inner speech. eLife, 6, e28197. https://elifesciences.org/articles/28197
Research funding:
  • Whitford TJ, Spencer KM, Harris AWF. Deciphering the electrophysiological signature of inner speech. Australian Research Council (ARC) Discovery Project, DP170103094, AU$304,000.