The Prehistory of Schneider's First-Rank Symptoms: Texts From 1810 to 1932

Soundless voices, silenced selves: are auditory verbal hallucinations in schizophrenia truly perceptual?

In much contemporary psychiatric training and practice, there is a strong emphasis on the audible or perceptual quality and externality of auditory verbal hallucinations in clinical assessments. A typical question during clinical assessment is asking whether the voices that a person hears sound identical to the way the clinician's voice is heard. In this Personal View, we argue that the most important factor in auditory verbal hallucinations in schizophrenia spectrum psychoses is a loss of first-person authority, and that a perceptual quality is not required for it to be this kind of hallucination. We draw on evidence from cognitive neuroscience showing that the activation of brain networks retrieved during capture of auditory verbal hallucinations that were experienced when a patient was in a functional MRI scanner does not match activation of networks retrieved during auditory perception. We propose that, despite early writings by Esquirol and Schneider that defined auditory verbal hallucinations as beliefs in perception rather than true perception, cognitive neuroscience, psychiatric training and practice, and patients adopting clinical vocabulary have been strongly influenced by the progression of the diagnostic criteria for schizophrenia, which increasingly place emphasis on language, such as the "full force" of a true perception. We hold that this change has resulted in an unhelpful top-down influence on the field, imposing perceptual qualities on auditory verbal hallucinations, and leading to misunderstandings and inaccuracies in clinical practice and patients' self-reports, and misinterpretations in cognitive neuroscience. We encourage a revision of the definition of auditory verbal hallucinations to move away from the necessity for auditory perception, and towards beliefs in perception due to the loss of first-person authority.

The Development of Non-affective Psychotic Syndromes in the 19th Century: LeGrand du Saulle and His 1871 Monograph "Le Délire De Persécutions" (Persecutory Delusions)

While the origins of two of Kraepelin's three subtypes of dementia praecox (DP), catatonic and hebephrenic, are well understood, no similar clear narrative exists for his concepts of paranoia and paranoid DP, which require a consideration of both German and French sources. An important milestone in the French literature is the massive 524 page monograph entitled "Le Délire Des Persécutions" published in 1871 by Henri Legrand du Saulle which contained extensive, clinically detailed descriptions of a wide range of cases with prominent, organized persecutory delusions. Many of his cases reported auditory hallucinations (AH), and some bizarre, Schneiderian delusions. The delusional content could evolve to include prominent somatic and/or grandiose themes. Using a symptomatic diagnostic framework, Legrand du Saulle proposed that this syndrome represented an independent "species" of mental illness. He sought to give a voice to the affected individuals, including a chapter devoted entirely to their writings. He described several clinically fascinating features of such patients including how often they moved residence to unsuccessfully flee their persecutors and how delusional beliefs could be communicated to spouses and relatives. Unlike Kraepelin, he was little interested in their course of illness or rates of deterioration, except to note that recoveries occurred in 20% of cases. The clinical richness of this work substantially exceeded that in the contemporaneous German literature. Most of the cases described by du Saulle would fit easily into the two major non-affective delusional syndromes articulated 28 years later in Kraepelin's famous 6th edition of his textbook: paranoia and paranoid DP.

What are delusions? Examining the typology problem

Delusions are a heterogenous transdiagnostic phenomenon with a higher prevalence in schizophrenia. One of the most fundamental debates surrounding the philosophical understanding of delusions concerns the question about the type of mental state in which reports that we label as delusional are grounded, namely, the typology problem. The formulation of potential answers for this problem seems to have important repercussions for experimental research in clinical psychiatry and the development of psychotherapeutic tools for the treatment of delusions in clinical psychology. Problematically, such alternatives are scattered in the literature, making it difficult to follow the current development and state of the target discussion. This paper offers an updated critical examination of the alternatives to the typology problem currently available in the literature. After clarifying the two main philosophical views underlying the dominant formulation of the debate (interpretivism and functionalism), we follow the usual distinction between doxastic (the idea that delusions are a type of belief) and anti-doxastic views. We then introduce two new sub-distinctions; on the doxastic camp, we distinguish between revisionist and non-revisionist proposals; on the anti-doxastic camp, we distinguish between commonsensical and non-commonsensical anti-doxasticisms. After analyzing the main claims of each view, we conclude with some of the most fundamental challenges that remain open within the discussion. This article is categorized under: Philosophy > Foundations of Cognitive Science Philosophy > Consciousness Philosophy > Psychological Capacities Neuroscience > Cognition.

Abnormal Oculomotor Corollary Discharge Signaling as a Trans-diagnostic Mechanism of Psychosis

BACKGROUND AND HYPOTHESIS

Corollary discharge (CD) signals are "copies" of motor signals sent to sensory areas to predict the corresponding input. They are a posited mechanism enabling one to distinguish actions generated by oneself vs external forces. Consequently, altered CD is a hypothesized mechanism for agency disturbances in psychosis. Previous studies have shown a decreased influence of CD signals on visual perception in individuals with schizophrenia-particularly in those with more severe positive symptoms. We therefore hypothesized that altered CD may be a trans-diagnostic mechanism of psychosis.

STUDY DESIGN

We examined oculomotor CD (using the blanking task) in 49 participants with schizophrenia or schizoaffective disorder (SZ), 36 bipolar participants with psychosis (BPP), and 40 healthy controls (HC). Participants made a saccade to a visual target. Upon saccade initiation, the target disappeared and reappeared at a horizontally displaced position. Participants indicated the direction of displacement. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of pre-saccadic target to inform perception. Thus, multi-level modeling was used to examine the influence of target displacement and saccade landing site on displacement judgements.

STUDY RESULTS

SZ and BPP were equally less sensitive to target displacement than HC. Moreover, regardless of diagnosis, SZ and BPP with more severe positive symptoms were more likely to rely on saccade landing site.

CONCLUSIONS

These results suggest that altered CD may be a trans-diagnostic mechanism of psychosis.

Self-Disorder in Schizophrenia: A Revised View (1. Comprehensive Review-Dualities of Self- and World-Experience)

A growing body of research supports the role of self-disorders as core phenotypic features of schizophrenia-spectrum disorders. Self-disorders comprise various alterations of conscious experience whose theoretical understanding continues to present a challenge. The following 2 articles aim to provide further clarification of the nature of self-disorders in schizophrenia by offering a comprehensive review (article 1) and theoretical revision (article 2) of the currently most influential model of altered selfhood in schizophrenia: the basic-self-disturbance or ipseity-disorder model (IDM). This article presents a state-of-the-art overview of the current self-disturbance model and critically assesses its descriptive adequacy with respect to the clinical variability and heterogeneity of the alterations in self- and world-awareness characteristic of schizophrenia. Special attention is paid to experiences of exaggerated basic self, increased "grip" or "hold" on the world, and paradoxical combinations. The next article proposes a theoretical revision of the self-disturbance model by considering how hyperreflexivity might form the crucial common thread or generating factor that unifies the phenomenologically heterogeneous, and sometimes even contradictory features of schizophrenic self-disorders. We outline the implications of our revised model for explanatory research, therapeutic practice, and our general understanding of the abnormalities in question.

Pre-saccadic shifts of attention in individuals diagnosed with schizophrenia

INTRODUCTION

Pathophysiological theories of schizophrenia (SZ) symptoms posit an abnormality in using predictions to guide behavior. One such prediction is based on imminent movements, via corollary discharge signals (CD) that relay information about planned movement kinematics to sensory brain regions. Empirical evidence suggests a reduced influence of sensorimotor predictions in individuals with SZ within multiple sensory systems, including in the visual system. One function of CD in the visual system is to selectively enhance visual sensitivity at the location of planned eye movements (pre-saccadic attention), thus enabling a prediction of the to-be-foveated stimulus. We expected pre-saccadic attention shifts to be less pronounced in individuals with SZ than in healthy controls (HC), resulting in unexpected sensory consequences of eye movements, which may relate to symptoms than can be explained in the context of altered allocation of attention.

METHODS

We examined this question by testing 30 SZ and 30 HC on a pre-saccadic attention task. On each trial participants made a saccade to a cued location in an array of four stimuli. A discrimination target that was either congruent or incongruent with the cued location was briefly presented after the cue, during saccade preparation. Pre-saccadic attention was quantified by comparing accuracy on congruent trials to incongruent trials within the interval preceding the saccade.

RESULTS

Although SZs were less accurate overall, the magnitude of the pre-saccadic attention effect generally did not differ across groups nor show a convincing relationship with symptom severity. We did, however, observe that SZ had reduced pre-saccadic attention effects when the discrimination target (probe) was presented at early stages of saccade planning, when pre-saccadic attention effects first emerged in HC.

CONCLUSION

These findings suggest generally intact pre-saccadic shifts of attention in SZ, albeit slightly delayed. Results contribute to our understanding of altered sensory predictions in people with schizophrenia.

Tracing the Roots of Dementia Praecox: Charles Lasègue and his 1852 Essay "Du Délire De Persécutions" (On Persecutory Delusions)

While the evolution of our modern concepts of mania and melancholia over the 19th century is relatively well-understood, no such clear narrative exists for the nonaffective psychotic syndromes that culminated in Kraepelin's concept of dementia praecox in 1899. These narratives were relatively distinct in Germany and France. An important milestone in the French literature is the 1852 essay by the alienist and polymath Charles Lasègue which contained the first detailed modern description of a persecutory delusional syndrome. Lasègue was a careful clinical observer who emphasized a symptomatic approach to psychiatric nosology and was less concerned with course and outcome. He details the evolution of persecutory delusions from increasing referential observations of real events, to the resulting anxious confusion and then the emergence of explanatory delusional beliefs. Once formed, these beliefs, he notes, are relatively impervious to correction. Lasègue was unusual for his time in emphasizing a "first-person perspective" on psychotic experiences, and quotes from his patients in his case history, of which he presents 15. Of these, 12 had auditory hallucinations and 4 passivity phenomena. While conceptualized differently than mid-19th century pre-Kraepelinian German writing on delusional syndromes, and unique on its focus on persecutory delusions, Lasègue's important essay shared a common view on the key features of a broad nonaffective delusional-hallucinatory syndrome. It was this syndrome that Kraepelin, over multiple drafts in the first 6 editions of his textbook from 1883 to 1899, was to divide into his mature concepts of paranoia and the paranoid subtype of dementia praecox.

Schneider's first-rank symptoms have neither diagnostic value for schizophrenia nor higher clinical validity than other delusions and hallucinations in psychotic disorders

The validity of studies on the diagnostic significance of first-rank symptoms (FRS) for schizophrenia has been put in doubt because of a poor compliance with Schneider's criterion for their definition and the lack of use of the phenomenological method for their assessment. In this study, using a rigorously phenomenological approach to elicit FRS, we examined (a) the degree to which unequivocally present FRS differentiated schizophrenia (n=513) from other psychotic disorders (n=633), and (b) the comparative validity between FRS and other reality-distortion symptoms against 16 external validators in the whole sample of psychotic disorders (n=1146). Diagnostic performance indices (with 95% CIs) of FRS for diagnosing schizophrenia were as follows: sensitivity=0.58 (0.54-0.61), specificity=0.65 (0.62-0.67), positive predictive value=0.57 (0.54-0.60) and negative predictive value=0.65 (0.63-0.68). While the overall association pattern of FRS and non-FRS scores with the validators was rather similar, three validators (premorbid social adjustment, number of hospitalizations and global assessment of functioning) were significantly related to non-FRS scores (p < 0.006) but not to FRS scores (p > 0.05). Furthermore, no validator was significantly related to FRS scores and unrelated to non-FRS scores, all of which indicates an overall better predictive validity for non-FRS delusions and hallucinations. These findings suggest that FRS do not have diagnostic value for diagnosing schizophrenia and that they do not meaningfully add to the external validity showed by other delusions and hallucinations. We believe that much of the misunderstanding about the diagnostic and clinical validity of FRS for schizophrenia is rooted in Schneider's confusing concept of the disorder.

The Doppelgänger phenomenon and death: a peculiar case of homicide by a subject with first-episode psychosis

The Doppelgänger phenomenon refers to the experience of a direct encounter with one's self, characteriswed by: (i) the perception of a figure with one's own identical physical features; or (ii) the apprehension that the perceived figure shares the same personality and identity. The Doppelgänger does not only look like the same person, it is his/her double. The perceptual element is usually a hallucination, although occasionally a false perception of an actual figure may be involved. This phenomenon has been described in individuals suffering from overwhelming fear, severe anxiety or intoxication, epilepsy, as well as in the sleep-wakefulness transition. It has also been reported in major psychoses. The fear of imminent death often precedes the Doppelgänger experience. This report presents the case of a 30-year-old man, Mr. Y, who was stabbed to death by Mr. X, his "double". The aggressor and his victim, although not related, were truly doubles; remarkably, they shared the same name and surname, age, professional activity and place of work. Moreover, they attended the same sports center but barely knew each other. The forensic psychiatric evaluations in Mr. X, subsequent to the crime committed, were suggestive of a psychotic condition. This case is unique in the scientific literature. In the most serious psychotic forms, the issue of the "double" calls into question not only the dissociative processes involved in the etiopathogenesis of the disorder, but also bio-psycho-social elements, as well as personal data in this case, which made the victim and the aggressor "identical". In the context of psychopathological functioning, the delusional mood (Wahnstimmung) that precedes the development of delirium is a sort of gateway to an impending psychotic illness, involving delusional awareness or mood (atmosphere). In psychosis, splitting is the main issue and this influence is seen as an evil, foreign, apocalyptic and unknown side no longer recognised as belonging to the self even in a physical sense. In such a situation, it is felt that the only way to survive is by suppressing one's double as a defense against disorganisation of the self.

Fronto-Temporal Disconnection Within the Presence Hallucination Network in Psychotic Patients With Passivity Experiences

Psychosis, characterized by hallucinations and delusions, is a common feature of psychiatric disease, especially schizophrenia. One prominent theory posits that psychosis is driven by abnormal sensorimotor predictions leading to the misattribution of self-related events. This misattribution has been linked to passivity experiences (PE), such as loss of agency and, more recently, to presence hallucinations (PH), defined as the conscious experience of the presence of an alien agent while no person is actually present. PH has been observed in schizophrenia, Parkinson's disease, and neurological patients with brain lesions and, recently, the brain mechanisms of PH (PH-network) have been determined comprising bilateral posterior middle temporal gyrus (pMTG), inferior frontal gyrus (IFG), and ventral premotor cortex (vPMC). Given that the experience of an alien agent is a common feature of PE, we here analyzed the functional connectivity within the PH-network in psychotic patients with (N = 39) vs without PE (N = 26). We observed reduced fronto-temporal functional connectivity in patients with PE compared to patients without PE between the right pMTG and the right and left IFG of the PH-network. Moreover, when seeding from these altered regions, we observed specific alterations with brain regions commonly linked to auditory-verbal hallucinations (such as Heschl's gyrus). The present connectivity findings within the PH-network extend the disconnection hypothesis for hallucinations to the specific case of PH and associates the PH-network with key brain regions for frequent psychotic symptoms such as auditory-verbal hallucinations, showing that PH are relevant to the study of the brain mechanisms of psychosis and PE.

Review Article: Anabolic-Androgenic Steroids, Violence, and Crime: Two Cases and Literature Review

BACKGROUND AND OBJECTIVES

Anabolic-androgenic steroid (AAS) use has become a major worldwide substance use disorder, affecting tens of millions of individuals. Importantly, it is now increasingly recognized that some individuals develop uncharacteristically violent or criminal behaviors when using AAS. We sought to summarize available information on this topic.

METHODS

We reviewed the published literature on AAS-induced behavioral effects and augmented this information with extensive observations from our clinical and forensic experience.

RESULTS

It is now generally accepted that some AAS users develop uncharacteristically violent or criminal behaviors while taking these drugs. Although these behaviors may partially reflect premorbid psychopathology, sociocultural factors, or expectational effects, accumulating evidence suggests that they are also attributable to biological effects of AAS themselves. The mechanism of these effects remains speculative, but preliminary data suggest a possible role for brain regions involved in emotional reactivity, such as the amygdala and regions involved in cognitive control, including the frontal cortex. For unknown reasons, these effects appear idiosyncratic; most AAS users display few behavioral effects, but a minority develops severe effects.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Professionals encountering AAS users in clinical or forensic settings should be alert to the possibility of AAS-induced violence or criminality and should employ strategies to assess whether AAS is indeed a contributory factor in a given case. Further research is needed to elucidate the mechanism of AAS-induced violence and to explain why only a subset of AAS users appears vulnerable to these effects. (Am J Addict 2021;00:00-00).

Kraepelin's Final Views on Dementia Praecox

In 1921, at the age of 65, 6 years after completing the final edition of his textbook, 22 years after first proposing the concept of dementia praecox (DP), and 1 year before retiring from clinical work, Emil Kraepelin completed the last edition of his "Introduction to Clinical Psychiatry," which contained a mini-textbook for students, 10 pages of which were devoted to DP. This work also included a series of new detailed case histories, 3 of which examined DP. This neglected text represents a distillation of what Kraepelin judged, near the end of his long career, to be the essential features of DP. The relevant text and case histories are translated into English for the first time. Kraepelin did not define DP solely by its chronic course and poor prognosis, acknowledging that remissions and even full recovery might be possible. His clinical description emphasized the frequency of bizarre delusions and passivity symptoms. He recognized the heterogeneity of the clinical presentations, outlining 6 subtypes of DP, including dementia simplex, depressive and stuporous dementia, and an agitated and circular DP. Kraepelin's original concept of DP was not impervious to change and expanded somewhat, especially with the inclusion of Diem's concept of simple DP. He also reviews several contributions of Bleuler, including his concept "latent schizophrenia." He writes poignantly of the psychological consequences of DP. His 3 DP cases, for advanced students, included simple DP, "periodic catatonic," and "speech confusion."

Thinking, believing, and hallucinating self in schizophrenia

In this Personal View, we discuss the history and concept of self-disturbance in relation to the pathophysiology and subjective experience of schizophrenia in terms of three approaches: the perceptual anomalies approach of the early Heidelberg School of Psychiatry, the ipseity model, and the predictive coding framework. Despite the importance of these approaches, there has been a notable absence of efforts to compare them and consider how they might be integrated. This Personal View compares the three approaches and offers suggestions as to how they might work together, which represents a novel position. We view self-disturbances as transformations of self that form the inseparable background against which psychotic symptoms emerge. Integrating computational psychiatric approaches with those used by phenomenologists in the first two listed approaches, we argue that delusions and hallucinations are inferences produced under extraordinary conditions and are both statistically and experientially as real for patients as other mental events. Such inferences still approximate Bayes-optimality, given the personal, neurobiological, and environmental circumstances, and might be the only ones available to minimise prediction error. The added contribution we hope to make focuses on how the dialogue between neuroscience and phenomenology might improve clinical practice. We hope this Personal View will act as a timely primer and bridging point for the different approaches of computational psychiatry and phenomenological psychopathology for interested clinicians.

A major flaw in the diagnosis of schizophrenia: what happened to the Schneider's first rank symptoms

Kurt Schneider introduced in the definition of the first-rank symptoms (FRS) the criterion that, where unequivocally present, the FRS are always psychological primaries and irreducible. This criterion, grounded on 'phenomenology' (description of subjective experiences), cannot be applied, according to Schneider, to delusions, either two-stage FRS delusional perception, or second-rank delusional notions. The Schneider's key criterion was neglected since the initial adoption of the 'Schneider's FRS' in the subsequent international literature (e.g. PSE, RDC, DSM, and ICD). The 'Schneider's FRS' (e.g. thought insertion, thought withdrawal, passivity, and influence) were persistently equivocated as 'delusions', in spite of the Schneider's FRS exclusion criterion. The internationally equivocated 'Schneider's FRS' (only homonymous of the original 'Schneider's FRS'), were eliminated in the DSM-5 and de-emphasized in ICD-11. However, the diagnostic value of the original 'Schneider's FRS', assessed on the basis of the strict compliance with the Schneider's criterion for their definition, was never determined. The 'damnatio memoriae' of the original Schneider's FRS may be premature. The definition and assessment of the 'experienced' symptoms of schizophrenia, only directly observed and reported by the patients, represent a specific, crucial, irreplaceable domain of psychopathology, to be carefully distinguished from the domain of the 'behavioral' symptoms observed by the clinician. Contemporary psychopathology research is aware of the absolute need for psychiatry to enhance precision and exactness in the definition of the experienced symptoms of schizophrenia, through the formulation of unequivocal inclusion and exclusion criteria (descriptive micro-psychopathology), in order to determine their value in research and care.

Associations between Self-Disorders and First-Rank Symptoms: An Empirical Study

BACKGROUND

The diagnostic weight of the first-rank symptoms was deemphasized in DSM-5 and a similar change is expected in ICD-11. This change was motivated by a lack of solid, empirical evidence of the diagnostic significance of first-rank symptoms for schizophrenia. Yet, it seems that Schneider's original concept of first-rank symptoms was overly simplified when it was introduced in DSM-III. Specifically, it was overlooked that first-rank symptoms, in Schneider's understanding, fundamentally involve a disorder of the self. The aim here is to empirically test Schneider's claim that first-rank symptoms involve self-disorders.

METHODS

In a modified, cross-sectional study of 98 first-admission patients, the relation between lifetime presence of first-rank symptoms and self-disorders was examined. Self-disorders were examined with the EASE (Examination of Anomalous Self-Experiences).

RESULTS

We found an odds ratio of 1.56 (95% CI 1.10-2.21) for having first-rank symptoms for each 5-point increase in the EASE (measuring self-disorder) using a generalized linear mixed model regression. We did not find first-rank symptoms in the absence of self-disorders.

CONCLUSION

The close relation between first-rank symptoms and self-disorders seems to support Schneider's original concept of first-rank symptoms. We suggest that first-rank symptoms occurring without the pervasively altered self-experiences might not be different from other psychotic phenomena in terms of their diagnostic significance. Awareness of self-disorders can help clinicians in assessing and detecting first-rank symptoms.

"Seeing Rain": Integrating phenomenological and Bayesian predictive coding approaches to visual hallucinations and self-disturbances (Ichstörungen) in schizophrenia

We present a schizophrenia patient who reports "seeing rain" with attendant somatosensory features which separate him from his surroundings. Because visual/multimodal hallucinations are understudied in schizophrenia, we examine a case history to determine the role of these hallucinations in self-disturbances (Ichstörungen). Developed by the early Heidelberg School, self-disturbances comprise two components: 1. The self experiences its own automatic processing as alien to self in a split-off, "doubled-I." 2. In "I-paralysis," the disruption to automatic processing is now outside the self in omnipotent agents. Self-disturbances (as indicated by visual/multimodal hallucinations) involve impairment in the ability to predict moment-to-moment experiences in the ongoing perception-action cycle. The phenomenological approach to subjective experience of self-disturbances complements efforts to model psychosis using the computational framework of hierarchical predictive coding. We conclude that self-disturbances play an adaptive, compensatory role following the uncoupling of perception and action, and possibly, other low-level perceptual anomalies.

The Two Faces of First-Rank Symptoms

Recently, there has been renewed interest in Schneider's first-rank symptoms (FRS) of schizophrenia, thanks in part to a meta-analysis of their diagnostic accuracy, which deserves much credit for its methodological rigor. Conceptualising FRS as a diagnostic test whose performance can be measured in terms of sensitivity and specificity involves some issues that require reflection. First, the full adequacy of sensitivity as a measure of diagnostic accuracy for FRS might be questioned. However, it is conceptually acceptable, though FRS are at a disadvantage as compared with many other psychiatric "diagnostic tests" that should have perfect sensitivity under ideal conditions. Also, from a psychopathological perspective it may well be argued that FRS cannot be conceptualised as a simple, inexpensive diagnostic test suitable for screening purposes; however, the history of the concept reveals some reasons why it may be legitimate to view them this way. While no other relevant study has appeared after the publication of the meta-analysis, data on a further 166 patients from a study that could not be included due to incompletely reported data were located. This brought the total to 4,236 patients from 17 studies on the ability of FRS to differentiate schizophrenia from other psychoses. The resulting summary estimates of sensitivity, specificity and positive and negative likelihood ratios are 60.2%, 75.9%, 2.50, and 0.52, respectively. FRS have a kind of double nature, as they can be legitimately considered as belonging to both a sophisticated framework grounded in phenomenological psychopathology and an eminently pragmatic framework grounded in clinical epidemiology. When FRS are conceptualised as simple clinical indicators that require low levels of inference, the available estimates of their diagnostic accuracy are a fairly valid appraisal of their performance and usefulness, and suggest that FRS have some value in differential diagnosis. However, when FRS are conceptualised as profoundly anomalous experiences that can be properly identified and evaluated only by using a phenomenological approach, these estimates can hardly be seen as a valid evaluation of their diagnostic significance. Phenomenologically informed studies are needed to address this research gap.