Tuesday 18 August 2015

Soundless Voices and Audible Thoughts

This post is by Clara Humpston (in the picture above), PhD student in the School of Psychology at Cardiff University. Her research focuses on the pathogenesis of psychotic symptoms and adopts a cognitive neuropsychiatric approach; by incorporating behavioural, neuroimaging, and phenomenological investigations, she aims to further contribute to a unified account of delusions and hallucinations. 

Here she summarises her recent paper, co-written with Matthew Broome (in the picture below), 'The Spectra of Soundless Voices and Audible Thoughts: Towards an Integrative Model of Auditory Verbal Hallucinations and Thought Insertion', published in Review of Philosophy and Psychology.

Thought insertion is currently described as a delusion and a first-rank symptom of schizophrenia, i.e. a false belief that the subject receives inserted, whereas auditory-verbal hallucinations (voices) are aberrant sensory perceptions in the absence of any external stimulus. Our paper suggests that beliefs (that is, if all delusional thoughts are indeed beliefs) and perception are interconnected which can also morph into one another, and that the phenomenology of psychosis needs to be understood not as isolated mental events but in its full totality and heterogeneity.

We argue that the experience of thought insertion alone is insufficient for a delusion to form and proposes a spectral model which links various psychotic symptoms by the degrees of agency and ownership involved. In essence, we think that the phenomenological ‘core’ of psychosis lies in the disturbances and permeation of one’s demarcation between self and other (i.e. an ego-boundary disorder). By ‘permeation’, we mean a two-way process of diffusion between the internal and external worlds, which is by no means simply a delusional elaboration.

In our opinion, the problems of agency and ownership in thought insertion and voice-hearing can be viewed on a continuum and not an all-or-none distinction. For example, the ‘standard approach’ of thought insertion points towards a diminished sense of agency yet with the sense of ownership intact. Our argument is that the presence of externally inserted thoughts alone is effectively an indication that there is no pre-reflective agency or ownership of the thoughts; however, this does not always mean the subject cannot be introspectively or reflectively aware that external thoughts have entered their mental space as a kind of meta-representation, yet still deny the thoughts are theirs.

In other words, there is a lack of pre-reflective ownership but not of reflective ownership. Delusional elaborations in turn can only form in the reflective stage; anything prior to this reflective process is at best an aberrant experience, albeit an experience which has high propensity to become a delusional thought/belief. The apparent implausibility and bizarreness of thought insertion are not necessary requirements for delusion formation, as many thoughts are very much delusional yet non-bizarre.

We support our arguments not only by some of the latest neurocognitive theories (e.g. a Bayesian approach to perceptual inference) but also by using first-person accounts and patients’ subjective reports of their experiences. In many of these accounts, the boundary between thought and perception is severely blurred, with phrases such as ‘vocalised thought’ and ‘thought-voices’. We take these as evidence of the sheer complexity of reality distortions in psychosis: when someone speaks of ‘hearing voices’, is it in a literal or a metaphorical sense? Does the inevitable delay between the formation and expression of a thought or perception distort its original experience?

We hope our paper offers at least some theoretical formulations as a starting point to exploring these questions.

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