The self, neuroscience and psychosis study: Testing a neurophenomenological model of the onset of psychosis

Basic self disturbance is a putative core vulnerability marker of schizophrenia spectrum disorders. The primary aims of the Self, Neuroscience and Psychosis (SNAP) study are to: (1) empirically test a previously described neurophenomenological self‐disturbance model of psychosis by examining the relationship between specific clinical, neurocognitive, and neurophysiological variables in UHR patients, and (2) develop a prediction model using these neurophenomenological disturbances for persistence or deterioration of UHR symptoms at 12‐month follow‐up.

assessments and electroencephalography.The UHR sample are followed up for a total of 24 months, with clinical assessment completed every 6 months.
Results: This paper presents the protocol of the SNAP study, including background rationale, aims and hypotheses, design, and assessment procedures.

Conclusions:
The SNAP study will test whether neurophenomenological disturbances associated with basic self-disturbance predict persistence or intensification of UHR symptomatology over a 2-year follow up period, and how specific these disturbances are to a clinical population with attenuated psychotic symptoms.This may ultimately inform clinical care and pathoaetiological models of psychosis.

| INTRODUCTION
Approximately a quarter of individuals at ultra-high risk (UHR) for psychosis will transition to a psychotic disorder over a 3-year period, a rate considerably higher than the general population and other clinical populations (Salazar De Pablo et al., 2021).The UHR phase is therefore a critical period for early intervention strategies, which have been shown to improve clinical outcomes (Correll et al., 2018;Killackey & Yung, 2007), reduce long-term economic burden (Aceituno et al., 2019;Behan et al., 2020), and reduce rates of psychosis onset (Addington et al., 2019;van der Gaag et al., 2013).However, despite the successes of early intervention strategies, accurate and replicable individual-level prediction of transition to psychosis from the UHR state remains elusive.Recent work has also identified the clinical significance of non-remission of UHR status, even if the person does not progress to threshold psychotic disorder (Beck et al., 2019;Cropley et al., 2016;de Wit et al., 2014).The ability to identify which UHR individuals are most likely to have persistent symptoms or to progress to full-threshold psychosis would enable more targeted treatments, as well as the development of novel treatments that specifically target identified risk factors.
One approach to improving on existing prediction models is to be guided by putative core vulnerability markers of schizophrenia spectrum disorders.The current study seeks to investigate the accuracy of basic self-disturbance, proposed to be one such core marker, together with the construct's neurocognitive and neurophysiological correlates, in predicting clinical outcome in UHR individuals.

| The phenomenology of schizophrenia Spectrum disorders
A strong candidate for a core phenomenological disturbance in schizophrenia spectrum disorders is disturbance of the basic sense of self (Burgin et al., 2022;Fusar-Poli et al., 2022;Henriksen et al., 2021;Nelson et al., 2008;Nelson, Parnas, & Sass, 2014;Parnas, 2011Parnas, , 2012;;Raballo et al., 2021;Sass & Parnas, 2003).The term 'basic self' refers to the pre-reflective and immediate consciousness or awareness of action, experience, and thought.Two nested concepts can be distinguished as constituting this aspect of selfhood: sense of ownership/mine-ness (I perceive my body, perceptions, and thoughts as my own) and sense of agency (I experience myself as the source of my actions and their consequences) (Gallagher, 2011).Crucially, these are generally implicit or automatic aspects of a basic sense of self, and provide the foundation for narrative aspects of selfhood (personal identity) and our engagement with other people and our environment (Zahavi, 2003).
Disturbance or instability of the basic self can manifest in a variety of anomalous subjective experiences.For example, an individual experiencing self-disturbance may feel as if their thoughts or body parts are not their own, or that they are not in full control of their actions.These experiences frequently result in perplexity, disorientation, difficulties with social functioning and understanding ('common sense'), and are profoundly distressing (Henriksen & Parnas, 2012).
Disturbed self-experience can intensify and crystallize over time into full-blown positive and negative psychotic symptoms (Fuchs, 2015;Henriksen & Parnas, 2012).Disturbance of the 'basic self' is far more prominent in schizophrenia spectrum disorders than other nonpsychotic psychiatric disorders (Henriksen et al., 2021;Nordgaard et al., 2023;Parnas et al., 2005), although see Madeira et al. (2017) and Sass et al. (2013) on aspects of basic self-disturbance that may also be present in other conditions, such as panic disorder and depersonalisation disorder (Sass, 2014).Basic self-disturbance is an independent predictor of future onset of schizophrenia spectrum disorders in UHR individuals (Nelson et al., 2012), and in adult (Parnas et al., 2011) and youth (Koren et al., 2020) clinical populations.The construct also shows a relationship with suicidality (Skodlar et al., 2008;Skodlar & Parnas, 2010), poor functioning (Haug et al., 2014;Raballo et al., 2016), and duration of untreated psychosis (Haug et al., 2017) in schizophrenia, and predicts poor recovery (Svendsen et al., 2019) and symptom persistence (Nordgaard et al., 2018) after a first episode of psychosis.
Together, this body of research indicates that, in the clinical context, measures of basic self disturbance may function as powerful diagnostic and predictive tools (Nordgaard & Henriksen, 2016;Parnas, 2012;Raballo et al., 2016).However, despite the apparent importance of basic self-disturbance in schizophrenia-spectrum disorders, little is known about the brain processes (i.e., neurocognitive, neurophysiological, neurostructural, neurofunctional processes) associated with this phenomenological disturbance.

| Neurocognitive models of self-disturbance
Two studies have identified relationships between basic self-disturbance and specific cognitive disturbances: extraction of temporally predictive information (Martin et al., 2017) and reaction to emotional stimuli (Sestito et al., 2015).In line with these findings, we have previously proposed that two specific neurocognitive disturbances, namely source monitoring deficits and aberrant salience, both of which are strongly implicated in psychosis (Griffin & Fletcher, 2017;Howes et al., 2020), may be associated with basic self-disturbance in schizophrenia spectrum disorders (Nelson, Whitford, et al., 2014b, c).
Source monitoring deficits refer to difficulties in making attributions about the origins of experiences, for example, whether an experience was real or imagined, or whether its origin was internal or external.It has been proposed that impaired corollary discharge prevents brain regions responsible for generating thoughts or actions from informing other brain regions that these thoughts or actions are self-generated (Crapse & Sommer, 2008;Stephan et al., 2009;Whitford et al., 2012).These thoughts or actions will therefore not be predicted and, consequently, will not be dampened in perception, as self-generated sensations (e.g., tickling oneself) normally are (Blakemore et al., 2000).This leads to difficulties in distinguishing events that we control from events that occur independently of us in the external world.Consequently, internal thoughts and actions (e.g., inner speech or motor commands) may be misattributed to external agents, evolving into psychotic symptoms such as auditory hallucinations and passivity phenomena (the feeling that an external agent is controlling one's body, feelings or thoughts) (Frith, 1992;Gawęda et al., 2013Gawęda et al., , 2014)).
Aberrant salience refers to reduced ability to suppress attention to irrelevant or familiar information or environmental stimuli, leading to an unusual salience of stimuli (Kapur, 2003;Kapur et al., 2005).Aberrant salience is thought to emerge from attention and memory disturbances that undermine the constraining and directing role that context normally plays in how events or stimuli are interpreted (Hemsley, 2005a, b).These disturbances may result in unusual aspects of the environment repeatedly entering a person's field of awareness, leading to connections being made between unrelated events in the environment and possibly, over time, delusional thinking.

| Neurophysiology of self-disturbance
Recent neurophysiological studies of basic self-disturbance in schizophrenia spectrum patients point towards abnormalities in emotional motor resonance (Ebisch & Gallese, 2015), somatosensory processing (Arnfred et al., 2015) and multisensory integration (Sestito et al., 2015).It has previously been proposed that dysconnectivity among sensory regions in the brain can lead to aberrant salience (Fletcher & Frith, 2009), and functional neuroimaging studies have consistently identified relationships between source monitoring processes and temporal lobe regions such as the superior temporal gyrus, which are associated with sensory processing and integration (Kowalski et al., 2021), and are also implicated in the neuropathology of schizophrenia spectrum disorders (Takahashi et al., 2009).
We and others have previously proposed (Hohwy, 2007;Nelson et al., 2020;Sass et al., 2018;Seth et al., 2011) that a common mechanism at play in both source monitoring deficits and aberrant salience may be aberrant predictive coding (Nelson et al., 2019(Nelson et al., , 2020)).Aberrant predictive coding involves an imbalance or mismatch between the encoding of sensory information and the brain's prior predictions, leading to prediction errors and misinterpreted stimuli, which have been implicated in psychotic symptoms (Ford & Mathalon, 2019).
Therefore, aberrant predictive coding may be an important contributor to basic self-disturbance on the phenomenological level and will be measured in the current study.

| Integration into a neurophenomenological self-disturbance model of psychosis
These streams of neurocognitive and neurophysiological research are remarkably consistent with the phenomenology of basic selfdisturbance (Nelson & Sass, 2017;Nelson, Whitford, et al., 2014b, c).A person's confusion regarding the origin of mental experiences associated with source monitoring deficits may contribute to diminished ownership of mental content and confusion of self-other boundaries.
Source monitoring deficits may also prompt consequential or compensatory forms of hyper-reflexivity (an inflated self-consciousness and awareness of aspects of one's experience that are normally tacit, implicit and 'in the background') of a reflective sort.Such hyperreflection might occur as an in-the-moment reaction (e.g., the sense that this thought did not originate in me leads to reflection on what its origins might be), but it may also turn into something more habitual, as the pattern of exaggerated reflection comes to be ingrained.
However, at a more basic or automatic level (Sass & Parnas, 2003), a form of hyper-reflexivity may already be present, since the very experience of one's thought as foreign (source monitoring deficit) implies that it is attended to as an object rather than being 'inhabited' implicitly as one's own.In other words, something that is normally implicit or tacit, experienced as a medium of selfhood, has been turned into the object of focal and objectifying awareness (Sass & Parnas, 2006).
Similarly, aberrant salience may contribute to various features of basic self-disturbance: rigidity and perplexity in interaction with others/the world; disturbance of common sense (shared, intuitive social understanding); loosened grip on the cognitive/perceptual world (the sharpness or stability with which meaning or perceptions emerge against a background context); frequent shifts in perspective that undermine the possibility of blocking out alternative perspectives (perspectival abridgement); weakened sense of the functional value (affordance value) of objects; and hyper-reflexivity.Thus, there are compelling reasons to believe that there is a correlational, if not a causal, relationship between these phenomenological and neurodisturbances, particularly given the specific prominence of these disturbances in schizophrenia spectrum disorders.
Our theoretical neurophenomenological model (Nelson, Whitford, et al., 2014b, c) predicts that these sets of disturbances will co-vary cross-sectionally and predict each other longitudinally.The study described in this protocol paper is an empirical evaluation of this proposal, as well as an examination of the predictive value of these measures for clinical outcome in UHR patients.

| Evidence from pilot data
Pilot data from three independent studies conducted by our team indicate that basic self-disturbance is significantly higher in both UHR and FEP individuals compared to healthy controls and independently predicts onset of psychotic disorders in UHR individuals over a 1-2 year follow-up period (Nelson et al., 2012(Nelson et al., , 2013)).Furthermore, source monitoring deficits were found to be a much stronger crosssectional predictor of basic self-disturbance than other clinical scales, including general psychopathology and positive symptoms (Nelson et al., 2020).Conversely, aberrant salience showed a stronger relationship with general psychopathology and positive symptoms than with basic self-disturbance.Finally, neurophysiological (EEG) data indicated reduced electrophysiological suppression to self-generated auditory sensations in UHR participants compared to healthy controls, in line with the proposed model.
Although this pilot data suggests greater relevance of source monitoring deficits than aberrant salience to basic self-disturbance, previous evidence suggests that aberrant salience is a neuro-construct with substantial theoretical support for being linked to basic selfdisturbance (Mishara, 2007;Mishara et al., 2016;Mishara & Fusar-Poli, 2013;Nelson & Sass, 2017;Nelson, Whitford, et al., 2014b;Raballo & Nelson, 2010), and should therefore be empirically evaluated in an adequately powered study.

| Study rationale
The pilot data, combined with evidence from existing studies, highlights the convergence of recent phenomenological, neurocognitive, and neurophysiological findings relating to self-disturbance in psychosis.However, the direct link between these domains has not yet been adequately investigated.Integration of these domains may assist in developing a model of why some UHR patients transition to psychosis (i.e., deterioration) or have persistent attenuated psychotic symptoms (i.e., persistence), while others do not.Identifying a core disturbance of the schizophrenia spectrum expressed at multiple levels (clinical, neurocognitive, neurophysiological) may assist with detecting UHR patients who are at greatest risk of persistence or intensification of disorder.This will assist, in turn, with directing interventions to the highest risk patients and in tailoring treatments to specifically target these risk factors, thus maximizing treatment impact.

| Primary Hypotheses
1. Basic self-disturbance, source monitoring deficits and aberrant salience (i.e., the phenomenological, neurocognitive, and neurophysiological measures) will be most severe in UHR patients, then clinical control patients, and then healthy control participants (UHR > clinical controls>healthy controls).
2. Basic self-disturbance will have a positive association with source monitoring deficits and aberrant salience as assessed by neurocognitive and neurophysiological measures in UHR individuals, after adjusting for other clinical (general psychopathology, positive and negative symptoms, substance use) and neurocognitive (memory, processing speed) variables.
3. Persistence/deterioration of symptoms in UHR individuals at 12-month follow-up will be predicted by self-disturbance (clinical measure), source monitoring deficits and aberrant salience (neurocognitive and neurophysiological measures) at baseline.

| Study setting
This study is being conducted at Orygen, a research institute and public youth mental health clinical service.UHR participants and clinical controls are being recruited from the Orygen Specialist Programmes and headspace youth mental health services, serving young people in the northern and western suburbs of Melbourne, Australia.Helpseeking participants who are being cared for and supported within community health services (i.e., GP clinics, mental health services) are also being recruited.The healthy control cohort is being recruited directly from the community.

| Participants
UHR participants (n = 400) are defined using the criteria presented in Table 1.Clinical controls (CC; n = 100) are help-seeking individuals from the same services who are experiencing psychiatric symptoms but no attenuated or frank psychotic symptoms.Healthy controls (HC; n = 50) are individuals who (1) are not help-seeking for mental health symptoms, (2) do not currently meet UHR criteria, (3) are not receiving any current treatment with psychotropic mediation, and (4) do not have a current mental health diagnosis.

| Design
All participants complete a baseline assessment consisting of a clinical interview, neurocognitive tasks, and electroencephalography (EEG).
T A B L E 1 Operationalized UHR intake criteria.The UHR sample will be followed up for 24 months, with a clinical assessment completed every 6 months (Figure 1).

| Outcome measures
At follow-up time points, participants who have transitioned to psychosis will be categorized as 'deteriorating' cases.Transition to psychosis is defined as threshold-level positive psychotic symptoms experienced daily for ≥1 week, as per the Comprehensive Assessment of At-Risk Mental States (CAARMS).Remission criteria requires no longer presenting with attenuated psychotic symptoms in the UHR range, as assessed using the CAARMS, along with good functioning (a SOFAS score of ≥70) or improved functioning (≥5-point improvement compared with baseline functioning).For the Trait and State Risk Factor and BLIPS groups, remission is defined as having achieved good functioning and no longer meeting criteria for schizotypal personality disorder (if present at baseline) and not having had onset of attenuated psychotic symptoms in the UHR range.Participants who do not meet these remission criteria at follow up time points will be categorized as 'persistent' cases.

| MEASURES
Table 2 summarizes the Schedule of Assessments for the study.

| Clinical measures
The Examination of Anomalous Self-Experience (EASE; Parnas et al., 2005) is used to measure basic self-disturbance.It provides a total score and five sub-domain scores (Cognition; Self-awareness and Presence; Bodily Experiences; Demarcation; Existential Reorientation).
The CAARMS (Yung et al., 2005) is used to establish UHR criteria and provide a continuous measure of attenuated psychotic symptom severity.The Negative Symptom Inventory-Psychosis Risk (NSI-PR; Strauss et al., 2020) is used to measure negative psychotic symptoms in the UHR population.The Brief Psychiatric Rating Scale (BPRS; Overall & Gorham, 1962) is used to provide an overall measure of general psychopathology.The Structured Clinical Interview for DSM-5 (SCID-5;First et al., 2015) is used to assess diagnostic criteria for DSM disorders.The Social and Occupational Functioning Assessment Scale (SOFAS; Goldman et al., 1992) is used to assess social and occupational functioning.The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST; WHO ASSIST Working Group, 2002), is used to measure substance use.

| General neurocognitive ability
A battery of neurocognitive tests assessing working memory, processing speed and verbal learning and memory using the Penn Computerized Neurocognitive Battery (Irani et al., 2012), is used to assess cognitive functioning in all groups.Estimated IQ is being measured using the Wide Range Achievement Test -Fifth Edition Reading Test (Wilkinson & Robertson, 2017).Further detail of the full neurocognitive battery can be found in Table 2.

| Source monitoring is assessed using three tasks:
Action Recognition Task (Moritz et al., 2009): Actions are presented to participants either verbally (short instructions) or nonverbally (icons).Some of the items require participants to physically perform the action whereas other actions are imagined.In the recognition phase of the task, participants are asked whether an action was previously displayed (verbally or nonverbally), whether it was a new action (not presented before), and if they had performed or imagined the action.
Temporal Binding Task (Haggard et al., 2002): Participants estimate the onset of their own willed hand movements using a specially designed clock.These hand movements sometimes elicit auditory sensations.The time interval between the perceived action and the resulting sensation is a useful proxy for an individual's sense of agency.
Word Recognition Test (Giráldez et al., 2000): During the initial phase, 30 words are presented.The participant is instructed to type conceptually related words.In the recognition phase, both computerand participant-generated words are presented.The participant is asked to remember if they wrote the word themselves or if the computer presented it to them.Two types of errors measure source monitoring deficits: internal attribution errors (participants inaccurately identify self-generated words as computer-generated) and external attribution errors (participants inaccurately identify computergenerated words as self-generated).

F I G U R E 1 Study overview.
T A B L E 2 Schedule of assessments.a All visits will have an acceptable visit window of ± 2 weeks.For example, a Month 6 visit can occur up to one-month prior to or after its due date.b The Baseline visit will be the final visit for participants in the clinical control and healthy control groups. c The CAARMS positive symptoms (worst in the past year) is completed at Screening in order to ensure eligibility.At all other timepoints that CAARMS positive symptoms (worst) will refer to the period since the last assessment.d Only the Reading Task of the WRAT-5 will be completed.e Only the LNB, DIGSYM, and PLLT tasks of the CNB will be completed.

| Source monitoring
Source monitoring is examined using the auditory button-press task (Horváth, 2015;Martikainen et al., 2005;Whitford et al., 2011).In this task, participants are trained to press a button, which causes an auditory tone to be delivered to the participants' headphones.For this task, the N1 component of the auditory evoked potential will be defined as the most negative peak occurring between 50 and 150 ms after stimuli onset.N1-suppression, which will be the dependent variable, will be calculated as the amplitude of the N1 component in the externally-generated condition minus the N1-amplitude in the selfgenerated condition.A motor-only condition will be included and used to subtract out the motor-evoked activity from the self-generated waveform.N1-amplitude will be measured from midline central electrode sites (i.e., FCz, Cz and CPz) as these are they sites at which N1-ampliude is maximal to bilateral auditory stimulation.

| Aberrant salience
Aberrant salience is measured neurophysiologically by the ability to inhibit redundant input (i.e., sensory gating) and an abnormal response to unpredictable auditory stimuli (e.g., the mismatch negativity (MMN; Javitt et al., 1995)).Two tasks are used in the current study: Sensory gating: Sensory gating will be quantified as the degree of suppression of the P50 component of the auditory-evoked potential elicited by an auditory 'click' stimulus when it is presented just after an identical stimulus, (i.e., a paired click design).

| Sample size calculation
The focus of sample size determination was primary aim 2 (development of a prediction model of persistence/deterioration of UHR patients at 12 months) because this aim would require the largest sample size.A rule of thumb for adequate sample size for the development of prediction models is to have 10 outcome events per parameter (Peduzzi et al., 1995(Peduzzi et al., , 1996)).With the available resources, 400 UHR participants are projected to be recruited to the study.Assuming a 20% drop-out rate by 12 months, the resulting sample would be 320.The 12-month UHR persistence/deterioration rate at 12 months is expected to be 50% (Polari et al., 2018).Thus, the study would have 160 events.This would allow up to 16 parameters to be included in the prediction model, which appears to be adequate for this aim.

| Primary aim 1: To test the neurophenomenological self-disturbance model
General linear models will be used to compare the three groups on baseline clinical, neurocognitive, and neurophysiological measures controlling for possible confounding variables such as age and gender.
Multiple linear regression will be used in each group to examine associations between basic self-disturbance and source monitoring deficits and aberrant salience, after adjusting for other clinical and neurocognitive variables.It is expected that significant relationships will be observed only in the UHR group.

| Primary aim 2:
To develop a prediction model for the persistence/deterioration of UHR patients Logistic regression will be used to examine the association between persistence/deterioration status at 1 year (yes/no) and basic selfdisturbance score, source monitoring deficits composite score and aberrant salience composite score.A logistic regression prediction model will then be developed using least absolute shrinkage and selection operator (LASSO) with the candidate predictors being the above scores as well as the scores of the clinical measures.The individual task scores of the neurocognitive and neurophysiological measures will also be considered as candidate predictors.

| Limitations
A limitation of this study is that, in order to minimize participant burden, some factors that might be relevant to basic self-disturbance, such as certain psychological, social and genetic factors (Sass et al., 2018), are not assessed.However, approximately 80% of SNAP participants are also participating in the Accelerating Medicines Partnership Schizophrenia (AMP SCZ) (Brady & Larrauri, 2023), a large international observational study with a comprehensive battery, including measures of social risk factors and stress exposure.These extra variables may be included in some SNAP study data analysis.

| CONCLUSION
The SNAP study will test whether neurophenomenological distur- to improve body-mind integration (Röhricht, 2009), the use of remyelination medications to address corollary discharge deficits (Whitford et al., 2012), and therapeutic approaches that address the overall framework of altered experience (Fusar-Poli et al., 2022) rather than specific contents of cognition, and focus on social disconnection, isolation and loneliness (Nelson et al., 2021).

ACKNOWLEDGEMENTS
This study is supported by a Wellcome Trust Flagship Award 2.7 | Study aims 2.7.1 | The Self, Neuroscience and Psychosis (SNAP) study has two primary aims: 1.To test the neurophenomenological self-disturbance model of psychosis by examining cross-sectional associations between clinical, neurocognitive, and neurophysiological characteristics in ultra-high risk for psychosis individuals compared to both clinical and healthy controls.2. To develop a prediction model using these neurophenomenological disturbances for illness persistence/deterioration (i.e., non-remission/transition to psychotic disorder) of UHR individuals at 12-month follow-up.2.7.2 | The study has several secondary aims: a.To test the specificity of the neurophenomenological model to schizophrenia-spectrum disorders.b.To explore the role of aberrant predictive coding in the neurophenomenological self-disturbance model.c.To explore the role of specific domains of basic self-disturbance in relation to neurocognitive and neurophysiological variables and in predicting outcomes of interest.d.To investigate the predictive accuracy of these neurophenomenological disturbances for persistence/deterioration of UHR patients at 6-month, 18-month and 24-month follow-up time points.
This study was approved by the Melbourne Health Human Research Ethics Committee (HREC/2020.044/MH/62 009) in 2020.Participant recruitment began in June 2021.3| METHODOLOGY3.1 | Study designThis is an observational study examining the validity and predictive accuracy of the neurophenomenological basic self-disturbance model of psychotic symptoms.
Inclusion criteria: (a) Aged 12-30 years inclusive, (b) sufficient fluency in English, (c) ability to give informed consent (parental/guardian consent is obtained for participants aged under 18 years), (d) meeting either UHR, clinical control, or healthy control criteria (see below).Exclusion criteria: (a) documented history of intellectual disability, (b) history of neurological conditions, (c) acquired brain injury, or (d) first episode psychosis.

f
Should it not be possible for the Neurocognitive and Neurophysiological measures to be completed at Baseline, they will instead be completed (a) for HC and CC: when possible, and (b) for UHR: nearest the closest timepoint.

4. 2
.2 | Aberrant salience is assessed using two tasks White Noise Task(Galdos et al., 2011): The White Noise Task is an experimental task for the illusion of speech in white noise.Participants are presented with 25 sound fragments in random order consisting of three types of stimuli: (1) white noise only, (2) white noise and clearly audible neutral speech, (3) white noise and barely audible neutral speech.Participants are asked to choose from five options: (1) hearing a positive voice, (2) hearing a negative voice, (3) hearing a neutral voice, (4) no speech heard, (5) heard speech but unsure whether the voice was positive, negative or neutral.The rate of hearing a voice in the white-noise only condition is the main variable of interest.Predictive Coding Task(Haarsma et al., 2020): This measure includes two tasks: a perceptual priors task and a cognitive priors task both of which manipulate and test the impact of expectations ('priors') on ambiguous sensory input.In the perceptual priors task, auditory stimuli (the phonemes 'Ba' or 'Da') are presented, with varying proportions of each phoneme, along with the visual image of a face pronouncing either 'Ba' or 'Da' (lip movement condition) or a still face (reference condition).The lip movements are used to create a perceptual bias towards a prior expectation (e.g., by lip movements indicating a 'Ba' sound rather than a 'Da' sound).In the cognitive priors task, a learned visual cue is presented (the visual image of the letters 'BA' or 'DA') and the participant is asked which phoneme they expect to be dominant in the following auditory sequence.500 ms after their judgement, the auditory phonemes 'Ba' or 'Da' are presented.In both the perceptual and cognitive tasks, the balance between the 'Ba' and 'Da' auditory phonemes are shifted in a stepwise fashion to converge on a point where the participant finds it difficult to distinguish which of the phonemes is dominant (the 'perceptual indifference' point).This point can be used to index the influence of perceptual and cognitive priors on perception.4.3 | Neurophysiological assessments (EEG recordings)Participants are fitted with a 64-electrode Quick-Cap EEG cap (Compumedics Neuroscan).EEG data are acquired on SynAmp2 hardware (Neuroscan, El Paso, Texas) and impedance is kept under 5kOhm.Data are continuously sampled at 1000 Hz, filtered online with a 0.5-100 Hz band-pass filter.Auditive stimuli are coded in Matlab and presented via professional headphones.Data will be processed offline using BrainVision Analyser 2 software (Brain Products GmbH, Munich).
bances associated with basic self-disturbance predict persistence or deterioration of UHR symptomatology over a 2-year follow-up period and how specific these disturbances are to a clinical population with attenuated psychotic symptoms.Identifying a core disturbance of the schizophrenia spectrum expressed at multiple levels (clinical, neurocognitive, neurophysiological) may assist with detecting UHR individuals who are at greatest risk of persistence or intensification of disorder.This will assist with (a) the development of mechanistic models, (b) guiding interventions towards highest risk patients, and (c) tailoring treatments to specifically target these core vulnerability markers, which may enhance treatment efficacy.Several potential interventions have been proposed for targeting basic self-disturbance, including body oriented psychological therapy

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UNS89574).BN was supported by an NHMRC Senior Research Fellowship (1137687) and a University of Melbourne Dame Kate Campbell Fellowship.KA is supported by a Dame Kate Campbell Fellowship from the University of Melbourne.AR was supported by an Independent Research Fund Denmark.Open access publishing facilitated by The University of Melbourne, as part of the Wiley -The University of Melbourne agreement via the Council of Australian University Librarians.