Plurality of formal thought disorders

I want to start off by making clear that formal thought disorders are not homogeneous or singular in nature. This has long been recognised in clinical psychopathology. There are different terms that attempt to codify what is observed and the plurality of these terms points out that there is probably no single abnormality being described. There are terms such as ‘loosening of association’, ‘derailment’, ‘circumstantiality’, ‘concrete thinking’, ‘tangentiality’, ‘perseveration’, ‘poverty of speech’ and ‘pressure of speech’. It can be seen that some of these terms refer to the form of language/thought, some speak to the dynamics of language/thought, and some to the fund of words in the content.

Finally, there is an underpinning concept that it is a loss or impairment of association of ideas that marks out formal thought disorders, even though this was never intended to describe a single abnormality. It is important to recognise that this concept of ‘association of ideas’ is a model to represent how we imagine that thinking emerges from preceding ideas. So, for Bleuler (Reference Bleuler1950), there is a loss of the continuity of associative threads and he proposed that some of the threads were determined by clang association (association of words based on how they sound rather than their meaning) or by incidental circumstances. We could add other potential determinants aside from the characteristics of words, including random internally generated images or the deleterious effects of impaired working memory on the flow of ideas. I am emphasising that there are formal thought disorders, rather than formal thought disorder. We would not assume, for example, that all types of tremor were derived from the same underlying anomaly and we ought not to assume that for formal thought disorders.

‘Pristine inner experience’

There is an assumption that the inner experience of thinking is in words, that it is a matter of language. But what we know from Russell Hurlburt (Reference Hurlburt1989, Reference Hurlburt2011) is that this is not necessarily the case. Hurlburt investigated what he terms ‘pristine inner experience’. Hurlburt’s investigation was an empirical study of actual inner subjective experience. By inner experience he means thoughts, feelings and sensations that momentarily appear in conscious awareness. These pristine experiences are unscripted, unedited and naturally occurring moments, revealed by use of descriptive experience sampling, a method developed by Hurlburt. Inner experience is shown to be fractionated, momentary events that appear as if unified in a stream. Hurlburt shows that the phenomena of inner experience include unsymbolised thinking, inner speech and visual perception. Thus, inner experience is a composite of disparate phenomena, only some of which is thinking as we normally imagine it.

In people with schizophrenia, Hurlburt showed that verbal thought was sometimes experienced as a disembodied voice that could be heard speaking without external sounds, but that had all the characteristics of rhythm, tempo and inflections as in normal speech. These inner experiences were also sometimes accompanied by wordless speech and imageless seeing. There were also reports of ‘no thought’, which one of his patients described as a ‘void within’ (Hurlburt Reference Hurlburt1989).

What Hurlburt’s work shows us is that our clinical observations of disordered language/ thought do not tell us much about the inner experience on which they are built and that our model of inner experience is mostly deduced from our observations of language and not from empirical investigations of subjective inner experience.

Assessment within the psychiatric interview

Palaniyappan et al’s (Reference Palaniyappan, Delgaram-Nejad and Chen2026, this issue) structured approach to the psychiatric interview is very much welcome, as it foregrounds formal thought disorders within the mental state examination and proposes practical clinical measures that can be taken to elicit these abnormal language phenomena. The approach is pragmatic and not a slavish adherence to some ideology about the nature of formal thought disorders. They make the point that formal thought disorders are clinical signs that need to be elicited, and propose several manoeuvres to increase the possibility of evoking them. They recognise the likelihood of time constraints and the constant pressures on clinicians working in busy clinical environments.

They do not ask what the purpose of making these inquiries is. It is implicit in their approach that they take a comprehensive assessment that includes an assessment of formal thought disorders to be a good in itself and I agree with them. Nonetheless, it is true that there is a decline of interest in clinical psychopathology and marked reduction in rigorous assessments of the mental state and an even greater disinterest in the recording of the actual utterance of patients. Part of the shift in interest is due to the belief that diagnostic purity is no longer important. The term ‘psychosis’ now stands in for both schizophrenia and bipolar disorder. This means that psychopathological features that might have been previously valued as clinical discriminators are of far less interest.

The renaissance of psychopathology?

With the likely introduction of artificial intelligence (AI) clinical assistants able to both take histories and conduct mental state examinations, a renaissance of interest in psychopathology may be upon us. These AI systems will be able to analyse rate of talk, pitch variability, prosody, energy of speech, latency of responses to inquiries and speech pauses. More importantly, AI will be able determine linguistic (semantic) coherence, syntactical complexity and semantic drift, which are features of formal thought disorders. The clinical methods discussed by Palaniyappan et al (Reference Palaniyappan, Delgaram-Nejad and Chen2026) will be of great importance, as they will induce the outputs that AI clinical assistants will rely on for analysis. To put it more strongly, the preserve of the human clinician will be consolidated in this scheme, as AI systems will only be able to analyse and summarise certain aspects of speech, whereas the clinicians’ claim to intersubjective attunement and phenomenological sensitivity will remain highly prized.