Modulating inner speech through non-invasive brain stimulation

Inner speech is an audible speech-like experience without hearing actual sounds. It takes place in many mental activities including thinking, reading, and dreaming. Due to its private and spontaneous nature, inner speech is difficult to study empirically. Most studies have relied on self-reported questionnaires and experience sampling methods after inner speech has taken place. New methods are needed to study the mental processes during inner speech processing and to delineate the neural signatures of inner speech.

Our previous research shows that inner speech can be spontaneously induced during silent reading of speech quotations (e.g., Mary said, “The dress is beautiful”). Using functional magnetic resonance imaging (fMRI), we found that inner speech was associated with increased neural activity in the right superior temporal sulcus (STS) areas (Yao, Belin, & Scheepers, 2011, 2012).

The current project aims to test the causal relationships between inner speech and the right STS areas using no-invasive brain stimulation. We will test in healthy adults (1) the laterality of inner speech experiences using transcranial direct current stimulation (tDCS) over the right vs. left STS, (2) the causality of the right STS to inner speech experiences using transcranial magnetic stimulation (TMS), and (3) the oscillatory signatures and entrainment of inner speech using transcranial alternating current stimulation (tACS). We will measure inner speech experience in reading (using eye tracking; e.g., Yao & Scheepers, 2011) and in speech perception (e.g., Yao et al., 2012).

The project has the potential for specifying the causal relationships between neural activity in certain brain regions and inner speech experiences. Building on our work on neurophysiological correlates of inner speech, the oscillatory signatures of inner speech in this project could provide an exciting opportunity for entrainment-based modulation of inner speech experience. The latter could have potential application in modulating auditory verbal hallucinations in schizophrenic patients.

Training/techniques to be provided -
The successful applicant will be trained in a wide range of research skills including experimental design, programming (MatLab, R), advanced statistics (mixed-effects modelling) and techniques such as speech analysis, eye tracking, transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial magnetic stimulation (TMS).


Candidates are expected to hold (or be about to obtain) a minimum upper second class honours degree (or equivalent) in experimental psychology, cognitive neuroscience, or another related subject. A Master’s degree in a relevant subject would be an advantage. Candidates with research experience in language processing and/or TDCS/TACS/TMS are encouraged to apply.