Is Hallucination Perceptual?

second in a triptych on hallucination

Is Hallucination Perceptual?

About a year ago, a friend of mine (a musician with whom I often performed at that time) shared with me that he had recently contracted such bad food poisoning that he began to hallucinate men in the tree in his yard wearing ‘safety yellow’ work clothes. He called the police. The experience was, as he reported it to me, indistinguishable from reality (or at least close enough that calling the police seemed the right thing to do.)

According to some philosophical accounts of hallucination, my friend is mistaken—he only believes himself to have had a perception-like experience. Last week (“Hallucination as Public and Private”) I suggested, contrary to these accounts, that hallucination can be public in the manner of perception—hallucinating can feel the same as perceiving.

Hallucination also has a private side. Many people who hallucinate are aware of their own propensity for hallucination, and some of us have recurring hallucinations that are generally easy to identify. Cecilia McGough, founder of the organization Students with Psychosis, has described how she regularly hallucinates the clown from a particular horror movie. As I described in the previous post, I regularly hear a particular person’s voice, especially while driving. Part of what it means to ‘hallucinate and know that you are’ is that the object of one’s hallucination is thus understood as private, unavailable to others.

In short, hallucination can be ‘public’ in the sense that it can feel just like perception of ordinary, publicly available, objects, but also ‘private’ in situations where one knows, or suspects, that one is hallucinating.

The point, today, is to relate these ideas, briefly, to recent calls in the psychiatric literature to revisit the ‘official’ definitions of hallucination (especially auditory verbal hallucination).

Traditional (i.e., late 20^th century and early 21^st century) psychiatric definitions of ‘hallucination’, as found in manuals such as DSM-5 and ICD-11, as well as in research literature [1], focus on two positive defining characteristics. First, hallucination is a (typically involuntary) “sensory perception” (ICD-11), “perception-like experience” (DSM-5), or “percept” [2]; and second, hallucination lacks an “appropriate (external) stimulus” (ICD-11), “external stimulation of the relevant sensory organ” (DSM-5), or “cognate external stimuli” [3]. This understanding extends (albeit not uniformly) to the psychoanalytic tradition, with Lacan, for example, reminding the reader of “the obvious fact that a hallucination is a perceptum without an object” [4].

The idea that hallucinations are ‘perception-like’ has recently been questioned by some psychiatrists, especially those working from the phenomenological tradition, and especially concerning auditory verbal hallucinations associated with schizophrenia. These authors have questioned whether it is best understood as necessarily (‘by definition’) perceptual [5], or at any rate whether the experience is always best characterized as “like hearing someone speak” [6].

For example, based on some first-person reports of hallucination, Parnas et al. conclude that hallucinations (specifically, auditory verbal hallucinations) may differ from perception in their “extreme phenomenological poverty and lack of temporal contour” [7]. Other differences have been sketched. For example, some have reported that their auditory hallucinations originate from very distant cities, or from nowhere in particular, and whatever these experiences are like for these people, it seems plausible that they differ in some ways from ‘ordinary perception’.

These calls for revision in how hallucination is conceived and diagnosed are timely and welcome. They tend to emphasize the importance of allowing the one who hallucinates to explore the nature of the experience without undue influence (for example, from clinicians who may unwittingly encourage understanding them in perceptual terms), and this freedom can aid in the construction of a “therapeutic alliance” that is in “the patient’s best interests” [8].

However, at the same time, it would be a shame if these recent critiques of the traditional psychiatric understanding of ‘hallucination’ replaced a prior dogma (‘hallucination is just like perception but without an external cause’) with a new one (‘hallucination is “not an experience similar to a veridical perception, but something that is much more ephemeral and private” [9]). Some studies continue to find that for a substantial number of people, “the perceptual quality of the voices is sometimes almost as real and loud as true perceptions” [10]. Some of my own experiences are in this category. In fact, occasionally voices and music are abnormally loud (which is another way to know that they are not heard by others).

This discussion leaves us with the original thought that hallucination can be both ‘public’ (perception-like in various ways) and ‘private’ (unavailable to others and understood to be so by the hallucinator). At least in some cases, this dual nature of the experience is perhaps one of its most important and consequential features. It leaves one inhabiting some sort of dualistic reality. The final post in this ‘triptych’ will explore that last point further.

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Notes

1. Ford et al. 2014; Lawn and ffytche 2021

2. Lawn and ffytche 2021, 290

3. Lawn and ffytche 2022, 290

4. Lacan 1966/2006, 446

5. Humpston and Woodward 2024; Parnas, Yttri, and Urfer-Parnas 2024; Moritz et al. 2024

6. Ratcliffe 2018

7. Parnas, Yttri, and Urfer-Parnas 2024, 85

8. Humpston and Woodward 2024, 664

9. Yttri et al. 2022, 663

10. Moritz et al. 2024, 27

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References

Ford, Judith, et al. 2014. Studying hallucinations within the NIMH RDoC framework. Schizophrenia Bulletin 40:S295–S304.

Humpston, C., and T. Woodward. 2024. Soundless voices, silenced selves: Are auditory verbal hallucinations in schizophrenia truly perceptual? Lancet Psychiatry 11:658–64.

Lawn, T., and D. ffytche. 2021. Cerebellar involvement in hallucinations may transcend clinical conditions and perceptual modalities. Cortex 143:290–4.

Lacan, J. 2006. Écrits: The First Complete Edition in English. trans. B. Fink. W. W. Norton & Company. (Original work published 1966.)

Moritz, S., L. Gawęda, W. Carpenter, A. Aleksandrowicz, L. Borgmann, J. Gallinat, and T. Fuchs. 2024. What Kurt Schneider really said and what the DSM has made of it in its different editions: A plea to redefine hallucinations in schizophrenia, Schizophrenia Bulletin 50(1):22–31.

Parnas, J., J. Yttri, and A. Urfer-Parnas. 2024. Phenomenology of auditory verbal hallucination in schizophrenia: an erroneous perception or something else? Schizophrenia Research 265:83–88.

Ratcliffe, M. 2018. Auditory verbal hallucinations and their phenomenological context. In Stanghellini et al. (2018), 789–802.

Stanghellini, Giovanni, Matthew Broome, Andrea Raballo, Anthony Fernandez, Paolo Fusar-Poli, and René Rosfort (2018) The Oxford Handbook of Phenomenological Psychopathology. Oxford University Press. DOI: 10.1093/oxfordhb/9780198803157.001.0001.

Yttri Janne-Elin, Annick Urfer-Parnas, and Josef Parnas (2022) Auditory Verbal Hallucinations in Schizophrenia, Part II: Phenomenological Qualities and Evolution. Journal of Nervous and Mental Disease 210(9):659–664.