Non-clinical Voice-hearers Research Articles

“Distress is probably the wrong word”: exploring uncertainty and ambivalence in non-clinical voice-hearing and the psychosis continuum

ABSTRACT Background Non-clinical voice-hearers (NCVHs) have been the subject of a growing body of psychological research, a primary aim of which is the development of new therapeutic techniques to support those who struggle with voice-hearing. However, relatively little research has examined non-clinical voice-hearing experiences beyond their relationship with clinical voice-hearing. Methods The present study consists of a qualitative re-analysis of 17 semi-structured interviews conducted as part of an NCVH neuroimaging study which included items from the Psychotic Symptoms Rating Scale (PSYRATS) and Positive and Negative Syndrome Scale (PANSS). Results were generated using thematic analysis. Results Analysis of interview responses showed that participants often experience negative voice content and negative emotion, but have frameworks which normalize a range of voice-hearing experiences. Participants also reported experiences which are not captured by standard clinical scales, as well as reporting comfort with uncertainty and ambiguity surrounding voices. Discussion These results indicate that much of the experience of NCVHs may be missed by clinical measures and concepts, suggesting a need to approach them in ways that go beyond typical understandings of the psychosis continuum.

Differing Pattern of Mismatch Negativity Responses in Clinical and Nonclinical Voice Hearers Challenge Predictive Coding Accounts of Psychosis

BackgroundAmong people with schizophrenia (PSZ), reduced mismatch negativity (MMN) is conceptualized as evidence of disrupted prediction error signaling that underlies positive symptoms. However, this conceptualization has been challenged by observations that MMN and positive symptoms are often uncorrelated. In the current study, we tested the hypothesis that reduced MMN is associated with the presence of hallucinations and delusions specifically rather than the presence of a psychiatric illness. A second aim was to determine whether the strength of the association with positive symptoms increases for indices that reflect predictions at higher levels of abstraction. MethodsFifty-six PSZ, 34 nonclinical voice hearers, and 48 healthy comparison subjects (HCs) completed 2 MMN paradigms: one with a simple duration deviant type, and one with a higher-level, pattern-violation deviant type. We also measured the repetition positivity, which reflects the formation of auditory memory traces. ResultsWe observed that although PSZ exhibited the expected pattern of significantly reduced simple duration deviant type and reduced pattern-violation deviant type at the trend level compared with HCs, nonclinical voice hearers exhibited a pattern of simple duration deviant type and pattern-violation deviant type amplitude that was statistically similar to that of HCs (ps > .64). Similarly, PSZ exhibited a significantly reduced repetition positivity slope compared with HCs in the duration condition and a trend-level reduction compared with HCs in the pattern-violation condition. Nonclinical voice hearers did not differ from either group in repetition positivity slope in either condition. ConclusionsThese results indicate that the MMN as a prediction error signal does not reflect processes relevant for the manifestation of hallucinations and delusions.

Senua’s psychosis in virtual reality: effects on mental health stigma

ABSTRACT Schizophrenia is probably the most stigmatised of all mental health conditions and many interventions have attempted to reduce this. This study examined how playing a serious virtual reality game might address stigmatised attitudes about severe mental illness, and schizophrenia in particular. The game chosen, Hellblade: Senua’s Sacrifice, contains a first-person experience of voice-hearing and other psychotic symptoms. We hypothesised that gameplay would increase Empathy, reduce Desire for social distance and improve attitudes to schizophrenia using measures adapted from prior work. We also measured participants’ beliefs about the voices heard by the protagonist, Senua, using the Beliefs about Voices Questionnaire-revised to compare to published data from both clinical and non-clinical voice hearers. 37 participants completed stigma measures both before and after experiencing 20 minutes of the game. Attitudes about schizophrenia significantly improved following the game, but empathy and desire for social distance did not. Results partially support the role that serious games can play in addressing mental health stigma. Overall, Senua’s voices were experienced very similarly to those of clinical voice hearers supporting the clinical veracity of the game depiction of psychosis.

Phenomenological and Cognitive Features Associated With Auditory Hallucinations in Clinical and Nonclinical Voice Hearers.

Auditory verbal hallucinations (AVH) are central features of schizophrenia (SZ). However, AVH also occur in a small percentage of the general population who do not have a need for care, termed nonclinical voice hearers (NCVH). We sought to determine the degree to which the experience of AVH was similar in NCVH and in people with schizophrenia (PSZ) and evaluate the degree to which NCVH shared other features of SZ such as delusional beliefs, cognitive impairment, and negative symptoms. We recruited 76 people with a DSM-V diagnosis of SZ/schizoaffective disorder (PSZ; 49 with current AVH, 27 without), 48 NCVH, and 51 healthy controls. Participants received a broad battery of clinician-administered and self-report symptom assessments and a focused cognitive assessment. The AVH of NCVH and PSZ shared very similar sensory features. NCVH experienced less distress, had greater control over their AVH, and, unlike PSZ, rarely heard 2 voices speaking to each other. NCVH demonstrated a wide range of deeply held unusual beliefs, but reported less paranoia, and fewer first-rank symptoms such as passivity and alterations in self-experience. NCVH showed no evidence of cognitive deficits or negative symptoms. The AVH in NCVH and PSZ demonstrate important similarities as well as clear differences. Specific features, rather than the presence, of AVH appear to determine the need for care. NCVH do not share the cognitive and motivational deficits seen in PSZ. These results suggest that AVH and unusual beliefs can be separated from the broader phenotype of SZ.

Time varying dynamics of hallucinations in clinical and non-clinical voice-hearers

Auditory verbal hallucinations (AVH) are frequently associated with psychotic disorders, yet also occur in non-clinical voice-hearers. AVH in this group are similar to those within clinical voice-hearers in terms of several phenomenological aspects, but non-clinical voice-hearers report to have more control over their AVH and attribute less emotional valence to them. These dissimilarities may stem from differences on the neurobiological level, as it is still under debate whether the mechanisms involved in AVH are the same in clinical and non-clinical voice-hearers. In this study, 21 clinical and 21 non-clinical voice-hearers indicated the onset and offsets of AVH during an fMRI scan. Using a method called leading eigenvector dynamics analysis (LEiDA), we examined time-varying dynamics of functional connectivity involved in AVH with a sub-second temporal resolution. We assessed differences between groups, and between hallucination and rest periods in dwell time, switching frequency, probability of occurrence, and transition probabilities of nine recurrent states of functional connectivity with a permutation ANOVA. Deviations in dwell times, switching frequencies, and switch probabilities in the hallucination period indicated more erratic dynamics during this condition regardless of their clinical status. Post-hoc analyses of the dwell times exhibited the most distinct differences between the rest and hallucination condition for the non-clinical sample, suggesting stronger differences between the two conditions in this group. Overall, these findings suggest that the neurobiological mechanisms involved in AVH are similar in clinical and non-clinical individuals.

Mediators of negative content and voice-related distress in a diverse sample of clinical and non-clinical voice-hearers.

Negative content in hearing voices (i.e., auditory verbal hallucinations) has been associated with adverse clinical outcomes including voice-related distress. Voice appraisals and responding mindfully to voices are theorized to reduce voice-related distress. This study aimed in examine mediators of the negative content voice-related distress relationship in clinical (those who recently received input from mental health services) and non-clinical voice-hearers. One hundred and twenty-one adults (71.9% female; 35.5% mixed or non-white ethnic background) who hear voices were recruited online and completed self-report measures of negative content of voices, voice-related distress, mindfulness of voices, interpretation of loss of control, thought suppression and intrusion. Clinical voice-hearers had significantly higher levels of negative content, voice-related distress and interpretation of loss of control than non-clinical voice-hearers. A mindful approach to voices and interpretation of loss of control mediated the relationship between negative content and voice-related distress across the whole sample. Thought suppression and intrusion did not mediate the relationship. The results support the use of mindfulness-based psychological intervention to reduce voice-related distress. Further development of valid and reliable measures specifically relating to constructs of voice content, voice-related distress and voice suppression will support further research in this area.

Benign and Pathological Religious Experience

In this paper, I draw on phenomenological analyses of religious voice-hearing and related experiences to elucidate the role of phenomenology in discerning benign from pathological religious experience. First, I present phenomenological discontinuities between cases of benign and pathological voice-hearing by drawing on a study of first-person accounts of voice-hearers within the Pentecostal movement which evinces that voice-hearing is not inherently pathological. Second, I introduce the epidemiological continuity of psychotic-like phenomena by drawing on a study of the contextual and responsive differences between clinical and non-clinical voice-hearers which point to the contexts wherein voice-hearing does not lead to pathology. Third, I present a successful case where the meaning of the anomalous experiences is validated and normalized by drawing on studies of mediumistic experience which illuminate its therapeutic benefits. Finally, I argue that failing to take the voice-hearer’s lived experience into account in the diagnostic moment can result in the pathologization of benign experiences.

Epistemic injustice amongst clinical and non-clinical voice-hearers: A qualitative thematic analysis study.

Research has suggested people who hear voices may be at risk of epistemic injustice. This is a form of discrimination whereby someone is unfairly judged to be an unreliable knower (testimonial injustice) or is unable to contribute to, and therefore access, concepts that make sense of their experience within mainstream society (hermeneutical injustice). Voice-hearing occurs both in people who are mental health service users and in the general population (clinical and non-clinical voice-hearers, respectively). The degree of distress and impairment associated with voices has been shown to relate to how individuals make sense of their experiences and how others respond to their identity as a voice-hearer. The aim of this study was to explore people's experiences of epistemic injustice in relation to voice-hearing and to understand how these may differ between clinical and non-clinical voice-hearers. A qualitative design was used. Eight clinical and nine non-clinical voice-hearers partook in semi-structured interviews, which were analysed using thematic analysis. Three pairs of themes related to (i) identity, (ii) relationships and (iii) power and position were constructed across the clinical and non-clinical groups, and two shared themes within both groups were created relating to testimonial and hermeneutical injustice. Both clinical and non-clinical voice-hearers described experiencing epistemic injustice in wider society. The presence of a 'safe haven' (e.g. spiritualist churches) for non-clinical voice-hearers ameliorated the impact of this to some degree, by allowing people to make connections with others with similar experiences within a non-judgemental and accepting community.

From core schemas about the self and others to voice phenomenology: Anxiety and depression affect voice hearers differently.

ObjectivesAuditory verbal hallucinations (AVHs) occur as a symptom in various mental disorders, and show different phenomenological aspects, depending on their underlying psychopathology. Anxiety and depression, which are known to be involved in the development of AVHs, are suggested to amplify a vicious cycle in which negative interpretations of daily experiences feed into the formation of negative core schemas about the self and others. However, the way in which these variables interrelate is still unknown. Therefore, our aim was to determine the specific roles of anxiety and depression in the relationship between core schemas and emotional aspects of AVHs for three groups (non‐clinical voice hearers, affective voice hearers and non‐affective voice hearers).MethodsPositive and negative core schemas of the self and others were tested as predictors of emotional distress due to AVHs, examining anxiety and depression separately as potential mediators.ResultsResults showed full mediating effects of depression in non‐affective voice hearers in the relationship between negative core schemas and AVH distress, but not in affective voice hearers. Anxiety was not a mediator in any of the groups.ConclusionsThese findings suggest different emotional mechanisms depending on the underlying psychopathology.

A data-driven linguistic characterization of hallucinated voices in clinical and non-clinical voice-hearers

BackgroundAuditory verbal hallucinations (AVHs) are heterogeneous regarding phenomenology and etiology. This has led to the proposal of AVHs subtypes. Distinguishing AVHs subtypes can inform AVHs neurocognitive models and also have implications for clinical practice. A scarcely studied source of heterogeneity relates to the AVHs linguistic characteristics. Therefore, in this study we investigate whether linguistic features distinguish AVHs subtypes, and whether linguistic AVH-subtypes are associated with phenomenology and voice-hearers' clinical status. MethodsTwenty-one clinical and nineteen non-clinical voice-hearers participated in this study. Participants were instructed to repeat verbatim their AVHs just after experiencing them. AVH-repetitions were audio-recorded and transcribed. AVHs phenomenology was assessed using the Auditory Hallucinations Rating Scale of the Psychotic Symptom Rating Scales. Hierarchical clustering analyses without a priori group dichotomization were performed using quantitative measures of sixteen linguistic features to distinguish sets of AVHs. ResultsA two-AVHs-cluster solution best partitioned the data. AVHs-clusters significantly differed in linguistic features (p < .001); AVHs phenomenology (p < .001); and distribution of clinical voice-hearers (p < .001). The “expanded-AVHs” cluster was characterized by more determiners, more prepositions, longer utterances (all p < .01), and mainly contained non-clinical voice-hearers. The “compact-AVHs” cluster had fewer determiners and prepositions, shorter utterances (all p < .01), more negative content, higher degree of negativity (both p < .05), and predominantly came from clinical voice-hearers. DiscussionTwo voice-speech clusters were recognized, differing in syntactic-grammatical complexity and negative phenomenology. Our results suggest clinical voice-hearers often hear negative, “compact-voices”, understandable under Broca's right hemisphere homologue and memory-based mechanisms. Conversely, non-clinical voice-hearers experience “expanded-voices”, better accounted by inner speech AVHs models.

Continuities and Discontinuities in the Cognitive Mechanisms Associated With Clinical and Nonclinical Auditory Verbal Hallucinations.

Auditory verbal hallucinations (AVHs) are typically associated with schizophrenia but also occur in individuals without any need for care (nonclinical voice hearers [NCVHs]). Cognitive models of AVHs posit potential biases in source monitoring, top-down processes, or a failure to inhibit intrusive memories. However, research across clinical/nonclinical groups is limited, and the extent to which there may be continuity in cognitive mechanism across groups, as predicted by the psychosis-continuum hypothesis, is unclear. We report two studies in which voice hearers with psychosis (n = 31) and NCVH participants reporting regular spiritual voices (n = 26) completed a battery of cognitive tasks. Compared with non-voice-hearing groups (ns = 33 and 28), voice hearers with psychosis showed atypical performance on signal detection, dichotic listening, and memory-inhibition tasks but intact performance on the source-monitoring task. NCVH participants, however, showed only atypical signal detection, which suggests differences between clinical and nonclinical voice hearers potentially related to attentional control and inhibition. These findings suggest that at the level of cognition, continuum models of hallucinations may need to take into account continuity but also discontinuity between clinical and nonclinical groups.

Psychophysiological stress-reactivity in clinical and non-clinical voice-hearers

BackgroundPsychosis is associated with dysregulation of psychophysiological stress-reactivity, including in subjective, autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) parameters. AimsThis study investigated whether dysregulated psychophysiological stress-reactivity is specifically associated with auditory verbal hallucinations (AVHs) or psychosis more generally by comparing voice-hearers with and without a need for care. MethodClinical (n = 20) and non-clinical voice-hearers (n = 23), as well as a healthy control group with no voices (n = 23), were compared on HPA and ANS responses, and subjective reactivity, to a psychophysiological stress paradigm, the socially evaluative cold pressor test. ResultsMeasures of HPA function in both clinical and non-clinical voice-hearers diverged from non-voice-hearing controls. Clinical participants showed a blunted peak response compared to both non-clinical groups (p = 0.02), whilst non-clinical voice-hearers showed, at trend-level, reduced cortisol levels during stress exposure compared to both clinical voice-hearers (p = 0.07) and healthy controls (p = 0.07), who unexpectedly did not differ from each other (p = 0.97). Clinical participants showed greater subjective stress levels than both non-clinical groups (p < 0.001), as well as greater anticipatory stress (p = 0.001) and less recovery. There were no differences between groups on parameters of the ANS (all p > 0.05). ConclusionsDysregulated psychophysiological stress-function is present in clinical voice-hearers, and partially discriminates them from non-clinical voice-hearers. Overall, the present findings identified specific potential psychophysiological markers of risk and resilience in auditory verbal hallucinations and need for care.

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

ABSTRACT 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.

Negative content in auditory verbal hallucinations: a natural language processing approach

ABSTRACT Introduction Negative content of auditory verbal hallucinations (AVH) is a strong predictor of distress and impairment. This paper quantifies emotional voice-content in order to explore both subjective (i.e. perceived) and objectively (i.e. linguistic sentiment) measured negativity and investigates associations with distress. Methods Clinical and non-clinical participants with frequent AVH (n = 40) repeated and recorded their AVH verbatim directly upon hearing. The AVH were analyzed for emotional valence using Pattern, a rule-based sentiment analyzer for Dutch. The AVH of the clinical individuals were compared to those of non-clinical voice-hearers on emotional valence and associated with experienced distress. Results The mean objective valence of AVH in patients was significantly more negative than those of non-clinical voice-hearers. In the clinical individuals a larger proportion of the voice-utterances was negative (34.7% versus 18.4%) in objective valence. The linguistic valence of the AVH showed a significant, strong association with the perceived negativity, amount of distress and disruption of life, but not with the intensity of distress. Conclusions Our results indicate that AVH of patients have a more negative linguistic content than those of non-clinical voice-hearers, which is associated with the experienced distress. Thus, patients not only perceive their voices as more negative, objective analyses confirm this.

A linguistic approach to the psychosis continuum: (dis)similarities and (dis)continuities in how clinical and non-clinical voice-hearers talk about their voices

ABSTRACT Introduction: “Continuum” approaches to psychosis have generated reports of similarities and differences in voice-hearing in clinical and non-clinical populations at the cohort level, but not typically examined overlap or degrees of difference between groups. Methods: We used a computer-aided linguistic approach to explore reports of voice-hearing by a clinical group (Early Intervention in Psychosis service-users; N = 40) and a non-clinical group (spiritualists; N = 27). We identify semantic categories of terms statistically overused by one group compared with the other, and by each group compared to a control sample of non-voice-hearing interview data (log likelihood (LL) value 6.63+=p < .01; effect size measure: log ratio 1.0+). We consider whether individual values support a continuum model. Results: Notwithstanding significant cohort-level differences, there was considerable continuity in language use. Reports of negative affect were prominent in both groups (p < .01, log ratio: 1.12+). Challenges of cognitive control were also evident in both cohorts, with references to “disengagement” accentuated in service-users (p < .01, log ratio: 1.14+). Conclusion: A corpus linguistic approach to voice-hearing provides new evidence of differences between clinical and non-clinical groups. Variability at the individual level provides substantial evidence of continuity with implications for cognitive mechanisms underlying voice-hearing.

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

BackgroundAuditory 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). MethodsControls 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. ResultsGroups 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. ConclusionsThese 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.

Paracingulate Sulcus Length Is Shorter in Voice-Hearers Regardless of Need for Care.

Hallucinations-while often considered an indication of mental illness-are commonly experienced by those without a need for clinical care. These nonclinical voice-hearers offer an opportunity to investigate hallucinations in the absence of confounds inherent to the clinical state. Recent work demonstrates an association between auditory verbal hallucinations (AVH) and structural variability in paracingulate sulcus (PCS) of medial prefrontal cortex in a clinical population. However, before PCS length may be considered a biomarker for clinical hallucination risk, it is necessary to investigate PCS structure in a nonclinical population of voice-hearers with AVH phenomenology similar to those of their clinical counterparts. In the current study, PCS length was measured from T1-weighted structural MRI scans of four groups of participants: (1) voice-hearers with a psychotic disorder (n = 15); (2) voice-hearers without a psychotic disorder (n = 15); (3) nonvoice-hearers with a psychotic disorder (n = 14); and (4) nonvoice-hearers without a psychotic disorder (n = 15). There was a main effect of AVH status-but not psychosis-on right PCS length, with no interaction of AVH and psychosis. Participants with AVH exhibited reduced right PCS length compared to participants without AVH (mean reduction = 8.8 mm, P < 0.05). While past studies have demonstrated decreased PCS length in clinical voice-hearers, ours is the first demonstration that shorter right PCS extends to nonclinical voice-hearers. Our findings support the hypothesis that differences in PCS length are related to the propensity to hear voices and not to illness, consistent with a continuum model of voice-hearing.

Characteristics of non-clinical hallucinations: A mixed-methods analysis of auditory, visual, tactile and olfactory hallucinations in a primary voice-hearing cohort

Phenomenological studies involving hallucinations in non-clinical populations have been relatively neglected, especially within the non-auditory realm. Relevant knowledge would help further a more nuanced understanding of the psychosis continuum. Participants (N=33) were non-clinical voice-hearers, who have experienced auditory verbal hallucinations, but with no known mental health diagnosis and not taking any prescribed psychiatric medications. A comprehensive hallucinations phenomenology interview was conducted to assess physical, cognitive and emotional characteristics of hallucinatory experiences across sensory domains. Mixed methods analysis was employed. Characteristics of reported AVHs were mostly in agreement with existing knowledge, though some deviations did exist (e.g. controllability). In addition, 50%, 24% and 29% of our voice-hearing sample experienced hallucinations in the visual, tactile and olfactory domains at least once a week. In contrast, delusions and disordered thinking were rare. Qualitative thematic analysis yielded added phenomenological insights into contextual triggers as well as the content and perceived purpose(s) of multisensory hallucinations. Our findings highlight lesser-reported data that hallucinations in non-auditory domains are relatively frequent in non-clinical voice-hearers. However, other psychotic-like symptoms (i.e. delusions and thought disorder) seem less common. These insights should be considered in the context of the psychosis continuum argument.

M53. EMOTIONAL SELF-VOICE PROCESSING AND ITS RELATIONSHIP WITH HALLUCINATORY PRONENESS

BackgroundSensory brain areas typically reduce their activity when we speak, allowing us to differentiate our own from someone else’s speech. Similarly, the amplitude of the N100 component of the EEG event-related potential in response to own speech is smaller than for passive listening to own or someone else’s speech. This amplitude suppression effect seems to be altered in voice hearers, which in turn could result in source misattribution (e.g., self-produced voice attributed to an external source). Emotion in speech can have a comparable effect, altering not only self-voice processing but also differentiation of the quality of auditory hallucinations in clinical and non-clinical voice hearers. For example, unlike in non-clinical voice hearers, auditory hallucinations in clinical voice hearers are usually derogatory in content and negatively affect daily functioning. Recent research strongly suggests that clinical and non-clinical voice hearers lie on a continuum ranging from low to high hallucinatory proneness. Based on this notion, the present study used EEG to investigate the effects of manipulations of self-voice quality in self-generated and passively listened-to self-voice as a function of hallucinatory proneness (HP) in healthy young adults. This is the first EEG study that examined the interplay of sensory suppression, emotion, and HP in a non-clinical population.MethodsParticipants varying in HP (according to the Launay Slade Hallucination Scale) participated in a standardized button-press task to elicit their own voice (compared to passively listening to it) in which the self-voice changed stepwise from fully neutral to fully emotional. The experimental task comprised three conditions: motor-to-auditory (MA), where the button-press generated the voice, auditory only (AO), where the voice was presented without the button press, and motor only (MO-a control condition to remove the motor related artifacts from the MA condition), where the button press did not generate the voice. Neutral and angry self-voice (single syllable ‘ah’ and ‘oh’ vocalizations of 500 ms duration) were recorded for each participant before the EEG acquisition. These voices were morphed to generate a neutral to angry continuum consisting of five stimuli ranging from fully neutral to fully angry: 100% neutral, 60-40% neutral-angry, 50-50% neutral-angry and 40–60% neutral-angry and 100% angry.ResultsPreliminary results with 17 participants show a significant effect of emotional self-voice quality on N1 suppression effect, with a larger suppression effect for the 100% angry as compared to 100% neutral self-voice. On the other hand, 60-40% neutral-angry, 50-50% neutral-angry and 40–60% neutral-angry self-voice show an enhancement effect. Furthermore, the results show a significant interaction of HP and voice quality on N1 suppression effect such that high HP showed no N1 suppression effect for the 100% neutral self-voice and an enhanced N1 effect when emotional quality of the self-voice increased.DiscussionThese data suggest that participants perceive the manipulations in the self-voice quality such that they recognize their own fully neutral and angry voice depicted by N100 suppression effect. Similarly, an N100 enhancement effect for 50-50% neutral-angry voice suggest that it is perceived as the most uncertain or peculiar of all the stimuli. Further, low and high HP show difference in N100 suppression effect for different voices, suggesting that HP may alter self-voice processing and these alterations are enhanced for emotional self-voice. This further supports the fact that abnormal perceptual experiences in voice hearers are higher when auditory hallucinations are emotional in nature.

M52. VOICES IN THE HEAD: AUDITORY VERBAL HALLUCINATIONS (AVH) IN HEALTHY INDIVIDUALS

BackgroundAuditory verbal hallucinations (AVH) are conscious sensory experiences occurring in the absence of external stimulation. AVH are experienced by 75% of individuals diagnosed with schizophrenia and can manifest in other neuropsychiatric disorders. However, AVH are also reported amongst healthy individuals. This implies that hearing voices is not necessarily linked to psychopathology. Amongst voice hearers, the likelihood of AVH seems to reflect individual differences in hallucination proneness (HP). The HP construct allows placing individuals on a psychosis continuum ranging from non-clinical to clinical experiences. Clinical voice hearers tend to misattribute internal events to external sources (externalization bias). Specifically, they seem to experience altered sensory feedback in response to self-initiated stimuli: Although more predictable, clinical voice hearers show similar, neurophysiological responses in reaction to self-initiated vs. externally presented stimuli. EEG studies suggest that this aberrance of prediction is associated with diminished N1-suppression effects that are observed in healthy individuals in response to self-initiated stimuli. Accordingly, clinical voice hearers may have problems differentiating between self-initiated and externally generated speech, potentially leading to externalization of their own speech. In line with this proposal, the current study focusses on non-clinical aspects of the psychosis continuum in healthy voice hearers and controls. This approach avoids confounding factors (medication, disease onset/duration etc.) that typically impede comparisons of clinical and non-clinical voice hearers. By utilizing insights on prediction from the forward model concept within the auditory-sensory domain, we want to investigate how N1-amplitudes in reaction to one’s own or someone else’s voice are modulated as a function of HP. Next to ascertaining the mechanism behind AVH, this research could give direction to identifying risk factors that potentiate the emergence of first-incidence psychosis.MethodsHP was assessed by means of the Launay-Slade Hallucination Scale. Each participant’s voice was recorded prior to EEG data acquisition (monosyllabic utterances, “ah” & “oh”, duration = 500 ms). Voice stimuli were morphed with an anchor voice, so that voice identity could be alternated from self- to other-voice (0%, 40%, 50%, 60%, 100%). To contrast neurophysiological responses between self- vs. externally generated voice stimuli, a well-established motor-to-auditory paradigm was used: In a motor-to-auditory condition (MAC) participants were prompted to press a button, thereby eliciting a voice stimulus (self-initiation). In an auditory-only condition (AOC), participants were prompted to passively listen to the voice stimulus (external generation). The motor-only condition (MOC), in which participants executed the button press only, served as a control condition to correct for motor activity in MAC.ResultsData from 38 participants replicate the classical N1-suppression effects for self-initiated vs. externally generated self-voice stimuli. This pattern of suppression is also visible for other-voice stimuli. Furthermore, current findings seem to replicate reversed N1-suppression for self-voice in individuals with high HP.DiscussionPreliminary findings suggest that HP modulates voice identity processing. More specifically, HP determines how voice stimuli are processed within the internal and external domain. Particularly, individuals with high HP show a reversal of N1-suppression for self-voice stimuli, which corroborates the external biasing hypothesis.