Investigating self-suppression and inner speech in people with schizophrenia

What is this research about?

Schizophrenia is a severe and debilitating mental disorder whose causes are not well understood.

It has long been noted that some unusual yet characteristic symptoms of schizophrenia seem to reflect the person misattributing, to external sources, self-generated actions and self-generated thoughts. For example, a delusions of control seems to reflect the misattribution of a self-generated action (‘He moves my body around like you might control a remote-control car’). On the other hand, a delusion of thought insertion seem to reflect the misattribution of a self-generated thought (‘These thoughts in my mind don’t belong to me, they’re his thoughts’). In a similar vein, auditory-verbal hallucinations (‘hearing voices) have been suggested to reflect inner speech that is misperceived as an externally-generated voice.

I am interested in the idea that these psychotic symptoms of are ultimately caused by sensory attenuation abnormalities to willed motor actions and willed thoughts. Along with my colleagues at UNSW and the Westmead Institute for Medical Research (WIMR), this project will use electroencephalography (EEG) to explore the mechanistic basis for sensory attenuation abnormalities in people with schizophrenia when they perform simple motor actions (such as willed vocalizations or willed hand movements) and simple mental actions (such as simple phonemes in inner speech). The hope is that by developing a better understanding of the neural basis of some of the most characteristic symptoms of schizophrenia, this research will inform the development of new, more effective treatments.

Other researchers working on this project
  • A/Prof. Anthony Harris (University of Sydney)
  • Dr. Oren Griffiths
  • Prof. Judith Ford (University of California – San Francisco)
  • Prof. Daniel Mathalon (University of California – San Francisco)
  • Prof. Martha Shenton (Harvard University)
  • A/Prof. Kevin Spencer (Harvard University)
  • Ms Ruth Elijah
  • Mr Daniel Pearson
  • Mr Sol Libesman
  • A/Prof. Mike Le Pelley
  • Dr Bradley Jack
Publications relating to this project
  • Whitford TJ, Oestreich LKL, Ford JM, Roach BJ, Loewy RL, Stuart BK, Mathalon DH. (in press, published online: 29 November 2017). Deficits in Cortical Suppression During Vocalization are Associated With Structural Abnormalities in the Arcuate Fasciculus in Early Illness Schizophrenia and Clinical High Risk for Psychosis. Schizophrenia Bulletin. https://doi.org/10.1093/schbul/sbx144
  • Oestreich LK, Mifsud NG, Ford JM, Roach BJ, Mathalon DH, Whitford TJ. (2015). Subnormal Sensory Attenuation to Self-Generated Speech in Schizotypy: Electrophysiological Evidence for a 'Continuum of Psychosis'. International Journal of Psychophysiology. 97,131-138
  • Whitford TJ, Ford JM, Mathalon DH, Kubicki M, Shenton ME. (2012). Schizophrenia, myelination, and delayed corollary discharges: A hypothesis. Schizophrenia Bulletin, 38(3), 486-494. https://doi:10.1093/schbul/sbq105
  • Whitford TJ, Mathalon DH, Shenton ME, Roach BJ, Bammer R, Adcock RA, Bouix S, Kubicki M, De Siebenthal J, Rausch AC, Schneiderman JS, Ford JM. (2011). Electrophysiological and diffusion tensor imaging evidence of delayed corollary discharges in patients with schizophrenia. Psychological Medicine, 41(5), 959-969. https://doi:10.1017/S0033291710001376
  • Whitford TJ, Kubicki M, Ghorashi S, Schneiderman JS, Hawley KJ, McCarley RW, Shenton ME, Spencer KM. (2011). Predicting inter-hemispheric transfer time from the diffusion properties of the corpus callosum in healthy individuals and schizophrenia patients: A combined ERP and DTI study. NeuroImage, 54(3), 2318-2329. https://doi:10.1016/j.neuroimage.2010.10.048
Research funding
  • Whitford. (2015-2018). Distinguishing self from world: understanding the neural basis of schizophrenia. National Health and Medical Research Council. Career Development Fellowship, $411,768