On "Hearing" Voices and "Seeing" Things: Probing Hallucination Predisposition in a Portuguese Nonclinical Sample with the Launay-Slade Hallucination Scale-Revised

Hallucination Proneness Alters Sensory Feedback Processing in Self-voice Production

BACKGROUND

Sensory suppression occurs when hearing one's self-generated voice, as opposed to passively listening to one's own voice. Quality changes in sensory feedback to the self-generated voice can increase attentional control. These changes affect the self-other voice distinction and might lead to hearing voices in the absence of an external source (ie, auditory verbal hallucinations). However, it is unclear how changes in sensory feedback processing and attention allocation interact and how this interaction might relate to hallucination proneness (HP).

STUDY DESIGN

Participants varying in HP self-generated (via a button-press) and passively listened to their voice that varied in emotional quality and certainty of recognition-100% neutral, 60%-40% neutral-angry, 50%-50% neutral-angry, 40%-60% neutral-angry, 100% angry, during electroencephalography (EEG) recordings.

STUDY RESULTS

The N1 auditory evoked potential was more suppressed for self-generated than externally generated voices. Increased HP was associated with (1) an increased N1 response to the self- compared with externally generated voices, (2) a reduced N1 response for angry compared with neutral voices, and (3) a reduced N2 response to unexpected voice quality in sensory feedback (60%-40% neutral-angry) compared with neutral voices.

CONCLUSIONS

The current study highlights an association between increased HP and systematic changes in the emotional quality and certainty in sensory feedback processing (N1) and attentional control (N2) in self-voice production in a nonclinical population. Considering that voice hearers also display these changes, these findings support the continuum hypothesis.

Revisiting alpha resting state dynamics underlying hallucinatory vulnerability: Insights from Hidden semi-Markov Modeling

BACKGROUND

Resting state (RS) brain activity is inherently non-stationary. Hidden semi-Markov Models (HsMM) can characterize continuous RS data as a sequence of recurring and distinct brain states along with their spatio-temporal dynamics.

NEW METHOD

Recent explorations suggest that HsMM state dynamics in the alpha frequency band link to auditory hallucination proneness (HP) in non-clinical individuals. The present study aimed to replicate these findings to elucidate robust neural correlates of hallucinatory vulnerability. Specifically, we aimed to investigate the reproducibility of HsMM states across different data sets and within-data set variants as well as the replicability of the association between alpha brain state dynamics and HP.

RESULTS

We found that most brain states are reproducible in different data sets, confirming that the HsMM characterized robust and generalizable EEG RS dynamics on a sub-second timescale. Brain state topographies and temporal dynamics of different within-data set variants showed substantial similarities and were robust against reduced data length and number of electrodes. However, the association with HP was not directly reproducible across data sets.

COMPARISON WITH EXISTING METHODS

The HsMM optimally leverages the high temporal resolution of EEG data and overcomes time-domain restrictions of other state allocation methods.

CONCLUSION

The results indicate that the sensitivity of brain state dynamics to capture individual variability in HP may depend on the data recording characteristics and individual variability in RS cognition, such as mind wandering. Future studies should consider that the order in which eyes-open and eyes-closed RS data are acquired directly influences an individual's attentional state and generation of spontaneous thoughts, and thereby might mediate the link to hallucinatory vulnerability.

Emotional anticipation for dynamic emotional faces is not modulated by schizotypal traits: A Representational Momentum study

Schizotypy, a personality structure that resembles schizophrenia symptoms, is often associated with abnormal facial emotion perception. Based on the prevailing sense of threat in psychotic experiences, and the immediate perceptual history of seeing others' facial expressions, individuals with high schizotypal traits may exhibit a heightened tendency to anticipate anger. To test this, we used insights from Representational Momentum (RM), a perceptual phenomenon in which the endpoint of a dynamic event is systematically displaced forward, into the immediate future. Angry-to-ambiguous and happy-to-ambiguous avatar faces were presented, each followed by a probe with the same (ambiguous) expression as the endpoint, or one slightly changed to express greater happiness/anger. Participants judged if the probe was "equal" to the endpoint and rated how confident they were. The sample was divided into high (N = 46) and low (N = 49) schizotypal traits using the Schizotypal Personality Questionnaire (SPQ). First, a forward bias was found in happy-to-ambiguous faces, suggesting emotional anticipation solely for dynamic faces changing towards a potential threat (anger). This may reflect an adaptative mechanism, as it is safer to anticipate any hostility from a conspecific than the opposite. Second, contrary to our hypothesis, high schizotypal traits did not heighten RM for happy-to-ambiguous faces, nor did they lead to overconfidence in biased judgements. This may suggest a typical pattern of emotional anticipation in non-clinical schizotypy, but caution is needed due to the use of self-report questionnaires, university students, and a modest sample size. Future studies should also investigate if the same holds for clinical manifestations of schizophrenia.

Prevalence and risk factors of self-reported psychotic experiences among high school and college students: A systematic review, meta-analysis, and meta-regression

BACKGROUND

Adolescents are at high risk of incident psychopathology. Fleeting psychotic experiences (PEs) that emerge in young people in response to stress may be warning signs that are missed by research that fails to study stressed populations, such as late high school and college/university students. Our aim in this systematic review was to conduct a meta-analysis that estimates prevalence rates of PEs in students, and to assess whether these rates differ by gender, age, culture, and COVID-19 exposure.

METHOD

We searched nine electronic databases, from their inception until January 31, 2022 for relevant studies. We pooled the estimates using the DerSimonian-Laird technique and random-effects meta-analysis. Our main outcome was the prevalence of self-reported PEs in high school and college/university students. We subsequently analyzed our data by age, gender, population, country, culture, evaluation tool, and COVID-19 exposure.

RESULTS

Out of 486 studies retrieved, a total of 59 independent studies met inclusion criteria reporting 210' 024 students from 21 different countries. Nearly one in four students (23.31%; 95% CI 18.41%-29.05%), reported having experienced PEs (heterogeneity [Q = 22,698.23 (62), p = 0.001] τ²  = 1.4418 [1.0415-2.1391], τ = 1.2007 [1.0205-1.4626], I²  = 99.7%, H = 19.13 [18.59-19.69]). The 95% prediction intervals were 04.01%-68.85%. Subgroup analyses showed that the pooled prevalence differed significantly by population, culture, and COVID-19 exposure.

CONCLUSION

This meta-analysis revealed high prevalence rates of self-reported PEs among teen and young adult students, which may have significance for mental health screening in school settings. An important realization is that PEs may have very different mental health meaning in different cultures.

The perceived salience of vocal emotions is dampened in non-clinical auditory verbal hallucinations

Introduction: Auditory verbal hallucinations (AVH) are a cardinal symptom of schizophrenia but are also reported in the general population without need for psychiatric care. Previous evidence suggests that AVH may reflect an imbalance of prior expectation and sensory information, and that altered salience processing is characteristic of both psychotic and non-clinical voice hearers. However, it remains to be shown how such an imbalance affects the categorisation of vocal emotions in perceptual ambiguity.Methods: Neutral and emotional nonverbal vocalisations were morphed along two continua differing in valence (anger; pleasure), each including 11 morphing steps at intervals of 10%. College students (N = 234) differing in AVH proneness (measured with the Launay-Slade Hallucination Scale) evaluated the emotional quality of the vocalisations.Results: Increased AVH proneness was associated with more frequent categorisation of ambiguous vocalisations as 'neutral', irrespective of valence. Similarly, the perceptual boundary for emotional classification was shifted by AVH proneness: participants needed more emotional information to categorise a voice as emotional.Conclusions: These findings suggest that emotional salience in vocalisations is dampened as a function of increased AVH proneness. This could be related to changes in the acoustic representations of emotions or reflect top-down expectations of less salient information in the social environment.

Validation of the Launay-Slade Hallucination Scale among Indian Healthy Adults

Psychotic Like Experiences (PLEs) have been reported in several cultures. The 16 item Launay-Slade Hallucination Scale-Extended (LSHS-E) measures hallucination like experiences (HLEs) in the general population. This study investigated the psychometric properties and the factor structure of LSHS-E Hindi among healthy adults of Delhi. LSHS-E was translated from English to Hindi and then back to English. It was administered as a paper pencil questionnaire to 182 adults from the general population. Reliability of LSHS-E Hindi was measured using Cronbach's alpha and factor structure was established using confirmatory factor analysis (CFA). It was tested against the Community Assessment of Psychic Experiences (CAPE-42) for convergent and divergent validity. Latent Class Analysis (LCA) was performed to identify subgroups with different endorsement of HLEs. Among 182, 18 participants reporting mental and neurological disorders were excluded. LSHS-E Hindi had good reliability (0.85; 95% CI: 0.82 to 0.88). CFA of Hindi LSHS-E revealed the a priori four-factor solution to be best, namely: 'intrusive thoughts', 'vivid daydreams', 'multisensory HLEs', 'auditory and visual HLEs'. LSHS-E Hindi showed stronger correlation with positive domain of CAPE than with negative and depression domains. LCA revealed three classes: low, intermediate and high endorsement of HLEs. Participants with highest endorsement of HLEs were less educated and had highest endorsement on all CAPE dimensions. LSHS-E Hindi has good psychometric properties and can be used to study HLEs in Indians. The four-factor structure model depicts the multidimensionality of HLEs, with 'intrusive thoughts' being the most commonly reported HLE in the sample. LCA supports the continuum hypothesis of HLEs.

Real and imagined sensory feedback have comparable effects on action anticipation

The forward model monitors the success of sensory feedback to an action and links it to an efference copy originating in the motor system. The Readiness Potential (RP) of the electroencephalogram has been denoted as a neural signature of the efference copy. An open question is whether imagined sensory feedback works similarly to real sensory feedback. We investigated the RP to audible and imagined sounds in a button-press paradigm and assessed the role of sound complexity (vocal vs. non-vocal sound). Sensory feedback (both audible and imagined) in response to a voluntary action modulated the RP amplitude time-locked to the button press. The RP amplitude increase was larger for actions with expected sensory feedback (audible and imagined) than those without sensory feedback, and associated with N1 suppression for audible sounds. Further, the early RP phase was increased when actions elicited an imagined vocal (self-voice) compared to non-vocal sound. Our results support the notion that sensory feedback is anticipated before voluntary actions. This is the case for both audible and imagined sensory feedback and confirms a role of overt and covert feedback in the forward model.

Changes in motor preparation affect the sensory consequences of voice production in voice hearers

BACKGROUND

Auditory verbal hallucinations (AVH) are a cardinal symptom of psychosis but are also present in 6-13% of the general population. Alterations in sensory feedback processing are a likely cause of AVH, indicative of changes in the forward model. However, it is unknown whether such alterations are related to anomalies in forming an efference copy during action preparation, selective for voices, and similar along the psychosis continuum. By directly comparing psychotic and nonclinical voice hearers (NCVH), the current study specifies whether and how AVH proneness modulates both the efference copy (Readiness Potential) and sensory feedback processing for voices and tones (N1, P2) with event-related brain potentials (ERPs).

METHODS

Controls with low AVH proneness (n = 15), NCVH (n = 16) and first-episode psychotic patients with AVH (n = 16) engaged in a button-press task with two types of stimuli: self-initiated and externally generated self-voices or tones during EEG recordings.

RESULTS

Groups differed in sensory feedback processing of expected and actual feedback: NCVH displayed an atypically enhanced N1 to self-initiated voices, while N1 suppression was reduced in psychotic patients. P2 suppression for voices and tones was strongest in NCVH, but absent for voices in patients. Motor activity preceding the button press was reduced in NCVH and patients, specifically for sensory feedback to self-voice in NCVH.

CONCLUSIONS

These findings suggest that selective changes in sensory feedback to voice are core to AVH. These changes already show in preparatory motor activity, potentially reflecting changes in forming an efference copy. The results provide partial support for continuum models of psychosis.

Self-voice perception and its relationship with hallucination predisposition

Introduction: Auditory verbal hallucinations (AVH) are a core symptom of psychotic disorders such as schizophrenia but are also reported in 10-15% of the general population. Impairments in self-voice recognition are frequently reported in schizophrenia and associated with the severity of AVH, particularly when the self-voice has a negative quality. However, whether self-voice processing is also affected in nonclinical voice hearers remains to be specified. Methods: Thirty-five nonclinical participants varying in hallucination predisposition based on the Launay-Slade Hallucination Scale, listened to prerecorded words and vocalisations differing in identity (self/other) and emotional quality. In Experiment 1, participants indicated whether words were spoken in their own voice, another voice, or whether they were unsure (recognition task). They were also asked whether pairs of words/vocalisations were uttered by the same or by a different speaker (discrimination task). In Experiment 2, participants judged the emotional quality of the words/vocalisations. Results: In Experiment 1, hallucination predisposition affected voice discrimination and recognition, irrespective of stimulus valence. Hallucination predisposition did not affect the evaluation of the emotional valence of words/vocalisations (Experiment 2). Conclusions: These findings suggest that nonclinical participants with high HP experience altered voice identity processing, whereas HP does not affect the perception of vocal emotion. Specific alterations in self-voice perception in clinical and nonclinical voice hearers may establish a core feature of the psychosis continuum.

A Cross-National Investigation of Hallucination-Like Experiences in 10 Countries: The E-CLECTIC Study

Hallucination-like experiences (HLEs) are typically defined as sensory perceptions in the absence of external stimuli. Multidimensional tools, able to assess different facets of HLEs, are helpful for a better characterization of hallucination proneness and to investigate the cross-national variation in the frequencies of HLEs. The current study set out to establish the validity, factor structure, and measurement invariance of the Launay-Slade Hallucinations Scale-Extended (LSHS-E), a tool to assess HLEs. A total of 4419 respondents from 10 countries were enrolled. Network analyses between the LSHS-E and the 3 dimensions of the Community Assessment of Psychic Experiences (CAPE) were performed to assess convergent and divergent validity of the LSHS-E. Confirmatory factor analysis was used to test its measurement invariance. The best fit was a 4-factor model, which proved invariant by country and clinical status, indicating cross-national stability of the hallucination-proneness construct. Among the different components of hallucination-proneness, auditory-visual HLEs had the strongest association with the positive dimension of the CAPE, compared with the depression and negative dimensions. Participants who reported a diagnosis of a mental disorder scored higher on the 4 LSHS-E factors. Small effect size differences by country were found in the scores of the 4 LSHS-E factors even after taking into account the role of socio-demographic and clinical variables. Due to its good psychometric properties, the LSHS-E is a strong candidate tool for large investigations of HLEs.

Measurement invariance of the Spanish Launay-Slade Hallucinations Scale-Extended version between putatively healthy controls and people diagnosed with a mental disorder

OBJECTIVES

The current study aimed at evaluating the reliability, convergent and divergent validity, and factor structure of the Spanish Launay-Slade Hallucinations Scale-Extended version (LSHS-E) in people with mental disorders and healthy controls.

METHODS

Four hundred and twenty-two individuals completed the Spanish LSHS-E and the Spanish Community Assessment of Psychic Experiences. The convergent and divergent validity of the LSHS-E was assessed with the three dimensions of the Community Assessment of Psychic Experiences (positive, negative, and depressive dimensions) in healthy controls and people with a mental disorder. Factor structure of the LSHS-E was assessed using confirmatory factor analysis and measurement invariance.

RESULTS

The LSHS-E had a good reliability in healthy controls and people with a mental disorder (Cronbach's = 0.83 and 0.91, respectively). The LSHS-E was more strongly associated with positive psychotic-like experiences than with depressive and negative symptoms. Four factors were found: (a) "intrusive thoughts"; (b) "vivid daydreams"; (c) "multisensory hallucination-like experiences"; and (d) "auditory-visual hallucination-like experiences" that were invariant between the group of healthy controls and people with a mental disorder.

CONCLUSION

The Spanish version of the LSHS-E possesses adequate psychometric properties, and the confirmatory factor analysis findings provide further support for the multidimensionality of proneness to hallucination in clinical and nonclinical samples.

Voice-selective prediction alterations in nonclinical voice hearers

Auditory verbal hallucinations (AVH) are a cardinal symptom of psychosis but also occur in 6–13% of the general population. Voice perception is thought to engage an internal forward model that generates predictions, preparing the auditory cortex for upcoming sensory feedback. Impaired processing of sensory feedback in vocalization seems to underlie the experience of AVH in psychosis, but whether this is the case in nonclinical voice hearers remains unclear. The current study used electroencephalography (EEG) to investigate whether and how hallucination predisposition (HP) modulates the internal forward model in response to self-initiated tones and self-voices. Participants varying in HP (based on the Launay-Slade Hallucination Scale) listened to self-generated and externally generated tones or self-voices. HP did not affect responses to self vs. externally generated tones. However, HP altered the processing of the self-generated voice: increased HP was associated with increased pre-stimulus alpha power and increased N1 response to the self-generated voice. HP did not affect the P2 response to voices. These findings confirm that both prediction and comparison of predicted and perceived feedback to a self-generated voice are altered in individuals with AVH predisposition. Specific alterations in the processing of self-generated vocalizations may establish a core feature of the psychosis continuum.